(first posted 9/7/2015. We don’t normally rerun QOTD posts, but the 372 comments in this one make for some fine reading)
The article the other day on the gen2 Seville, with all of its feeble engines, made me think: Just what were the 10 worst car engines ever? Well, who better than you all to answer that. And if a something even vaguely resembling a consensus develops,we’ll make an official CC List in a post. But I’m not holding my breath… Maybe I’ll just pick what I think is the best list and re-post it.
Just so that we keep it a bit real, let’s have a cut-off; only engines that appeared after 1965. Many of us here might not be familiar with the travails of the Copper-Cooled 1923 Chevy. But many of us will remember the hypereutectic alloys and other delights of a somewhat more recent Chevy.
I’m surprised no one has mentioned the flat six in the Corvair, unless is it disqualified because it was developed before 1965. In addition to being a notorious oil leaker/burner, the Corvair engine was especially prone to throwing its fan belt off as the belt would age and stretch. Without the belt, no fan to blow air across the cylinders and it would overheat. I’m sure that the Corvairs remaining in service have had the oil leakage problems addressed and that their owners make sure to monitor the tension on the fan belt. Given that the Corvair was marketed (at least in the beginning) as low cost transportation, GM was asking for trouble when it released this car on a public noted for ignoring routine maintenance until it was too late.
Briefly considered it, but it’s too old. Besides, as an owner of a ’66 I can say from experience it is far from being Top Ten Worst material although it does have it’s quirks.
Worst quirk is oil leaks: one time I tallied up all the potential places oil could leak from a flat 164 and I forget the exact number but IIRC it was close to 50! Well there are 12 individual push rod tubes with a “seal” on each end making 24 possible leaks right there. In yet another example of an idea that was doomed by inadequate tech or materials at the time, today’s Viton seals do a wonderful job of sealing those tubes. (Even though VW had similar tubes for years.) As far as I can tell, those tubes were the main culprits. Put Viton seals on them and the rest of the engine stays nice and oil tight.
Another quirk from failure to keep all sealed up was the heater system; any oil or exhaust leaks from the engine became immediately apparent if the heat was turned on. Hey- maybe GM did that on purpose to force owners to keep those leaks in check!
Much criticism is leveled at the Corvair’s twisty fan belt but really- I’ve owned my ’66 since 1984 and it’s only thrown a belt once, and I wasn’t surprised because I saw that the belt was failing but I’m the sort that has to extract the last mile out of things before I replace ’em. So I had another belt onboard, put it on at roadside, and went on my merry way. One ought to know right away to suspect the belt when the “ALT” light comes on. I’ve not seen any unusual appetite for fan belts from my Corvair.
The very earliest cars had a tendency to throw their belts, which was mitigated to a large extent by the deeper pulleys (a running change on 1960 models). Not so much the oil leaks…
I’ve read that the switch to the magnesium fan also helped keep the belt happy as it was lighter than the steel fan and didn’t load the belt as much on rapid accel/decel.
Belt throwing was a problem in 60. Not common after that.
As it happens the two Corvairs that I was most familiar with BITD were both 1960 models. One belonged to a neighbor who had purchased it new to commute back and forth to work. He was pretty good about changing the oil and performing other maintenance and it was still in pretty good shape when it was traded away, ca 1967. I can remember a conversation between him and my father in which he stated that he always carried a spare fan belt because the Corvair was prone to throw off the belt.
The other ’60 Corvair belonged to a good friend in high school. This car was your basic two hundred dollar beater that was purchased in the fall of 1968 to drive to high school. It was obvious that Hal was going to be the final owner of this car and it was treated accordingly. Oil burning/leakage was a major issue; at that time you could buy used motor oil for something like 18 cents a quart so SOP was to carry 5 or 6 quarts at all times. A couple of weeks after graduation Hal went out one morning to go to work and the motor in the Corvair was seized up solidly. It had run fine (at least as fine as it could) the night before; apparently if was low enough on oil that the heat in the block wouldn’t dissipate well enough once it was shut off. Needless to say the Corvair went off to the scrappers.
The belt throwing was quickly fixed in early 1960. Few of the newer Corvairs ever had that problem.
1600 dual port VW
Quad 4
Subaru flat four, recent edition
4.6 Ford V-8 with the plastic intake and the spark plugs shooting through the hood
305 Chevy, camshaft and timing chain failures
Mazda rotary
Vega four
267 Chevy
255 Ford
Celica 2zz four engine sludge
I think it was only the first few years of the 305…they had it straightened out by 82 or so.
Our 2002 F150 has the 4.6 Windsor built engine. Don’t know if a previous owner changed it or Ford had corrected the mistake by then, but I was mighty glad to see when we bought it in 2011 it had a all aluminum intake. And at 176,000 miles it doesn’t leak ( although it has started finally weeping oil from the oil filter adapter. Why oh why couldn’t they have just had the filter screw onto the block directly like all my other engines!).
Some of the engine choices posted I agree with and others I don’t. The fact that the 2.3l Pinto engine was slow does not make it a bad engine especially since it lasted for years in cars and was also turbo charged and fuel injected. In base guise it was a reliable and unexciting engine but it was not bad.
The same goes for the GM V8-6-4 engine. It was primitive computer control that made it run like crap but once a little wire was snipped, the engine was reliable and ran well.
The same in regards to the HT4100 engine. It was unreliable in its first years but by 1986 it was reworked and reliable enough. That engine would become the 4.5l and 4.9l engines in which both were reliable.
Interestingly enough even with the HT4100 and the V8-6-4 engines, Cadillac actually sold very well up until 1985 when the downsized Deville arrived looking too much like the Olds and Buick offerings and then sales tanked.
Well enough of the soap box. Here are my worse engines
1. GM 2.0/2.2l engines- Found in S- Series pickups, Cavaliers, Corsicas and a whole other host of cars, this engine eat head gaskets up
2. Olds Diesel- Most of those cars still around were converted to the Olds 307
3. Modified Nissan Z24i 2.4l engine for use in the US market Nissan Van from 87-90 and this version of the Z24 engine tended to catch fire so Nissan stepped in and bought almost all of them back.
4. GM Crossfire V8
5. Chrysler 318 Fuel Injected V8. This was found in the 80-83 Imperial and it was rubbish and ran poorly even with the carb conversion.
100% agree with your #1 on your list. My mother owned a 1984 Pontiac Sunbird (later given to my youngest sister) that blew through 2 brand new engines in less than 5 years…my mother did maintain it (oil changes, etc.) and I think the car only had 60k miles or so when the second engine went (threw a rod)..
My youngest sister is no longer with us, but I think this is the car that spooked her from buying any more American cars (my Mother still buys only American, but she sees things differently I guess).
Different engine. That was the Brazilian 2.0 SOHC.
Did the Sunbird have a different source of 2.0 engines than the Cavalier? Kind of doubt it…maybe they both were Brazilian 2.0’s? Anyway, terrible experience with that engine, made my Dad’s list of worst cars he ever bought new.
The fact that the 2.3l Pinto engine was slow does not make it a bad engine especially since it lasted for years in cars and was also turbo charged and fuel injected. In base guise it was a reliable and unexciting engine but it was not bad.
The 2.3L Lima was an epic engine, Ford Motorsport was squeezing close to 700 HP out of them in IMSA GTP.
Also got nearly 3 decades of use out of it, including a trick twin-spark head at the end. I think Ford still carries it as a crate engine in their performance catalog.
Cadillac 8-6-4
The Olds diesel
Originaln Chevy Vega engine
Northstar
From ones I have any sort of experience or knowledge on-
Cadillac HT4100-garbage, mainly because they rushed it into production. The 4.5 and 4.9 that were developed from it were actually pretty decent.
The v8-6-4 was fine itself, it was the computer that tried to deactivate the cylinders that didn’t work. It came too soon for the technology at the time, though the idea is solid and is now used to good effect by various companies.
The Northstar was, as someone else described it, hit or miss. I’ve seen some go over 200K, and I’ve seen some blow head gaskets before 100K. This is one of those engine/cars I really enjoy driving-as long everything is OK with it. Regardless, Cadillac had already screwed the pooch with their other crap engines and crap quality, this kind of continued bad reputation was not what they needed. Also unfortunately, like many other GM products of the time, it seems Cadillacs of this general era start dying the death of a thousand cuts even before they start having serious powertrain problems.
Ford 3.8 V6. I would guess that is simply why one doesn’t see a whole lot of FoMoCo cars from that era on the streets. I have to gawk when I see one of those fugly Continentals from this era because I’m just that surprised it isn’t in the junkyard with a blown head gasket.
Mopar 2.7L v6, crappy design with the oil sludge and all. Garbage, but I wonder if they managed to improve them because they put this engine in base 300s and Chargers into the 2000s.
The Mopar 2.7’s sludging issues were corrected sometime before they were put into the LX cars. I forget what caused the issue, but it was limited to early models.
Reportedly corrected by the 2002 models. The oil return passages were increased in size, so that oil drained properly into the sump instead of being blocked by accumulated sludge. Crankcase ventilation was changed, increased to reduce moisture accumulation and sludge formation. Actually I recall that as early as 1999, some mechanics were already substituting a higher-flow crankcase vent valve to accomplish the same thing. But because this was not tested and approved, it was in violation of EPA regulations, and of smog-control regulations in many states…another example of “Hi, I’m from the Government. I’m here to HELP you.”
And not in fact corrected. The 2002 and later versions of the 2.7 were just as bad.
Funny thing is if you make a list of the 10 worst automobile engines of all time, there will be a number of GM engines on it. Conversely, if you made a list of the 10 best, a number of GM engines would be on that list as well.
Some bad engines that come to my mind:
Cadillac 4.1L
Toyota 3VZE
Ford 3.8L V-6
Early Olds 350 diesel. 1982-up ‘DX’ versions were much improved. The 4.3L V-6 diesel was actually pretty good.
Mercedes 3.8L V-8
Turbocharged Detroit 8.2L diesels
Maserati Bi-Turbo
GMC Toro-Flow diesel
As for the V8-6-4 Cadillac, the engine itself was actually fine mechanically, it was the primitive electronics that caused the driveability issues that gave it a bad reputation.
I wonder if the Northstar will make both the best and worst engines list?
I’m surprised to see noboday other than Bob B mentioned the Maserati engine until now… The early ones had a na oiling fault which resulted in engines exploding at low miles; I believe they have dealt with that later but still one could never truct these things.
You know, considering how many different engines that have been offered in the U.S., it’s kind of amazing how few unique designs of the Big Three are on this list.
Almost all of the truly bad ones can be limited to the Vega and Cadillac HT4100 aluminum block-with-iron-heads monstrosities, the Olds diesels, a few early (for U.S. manufacturers) OHC engines, and that’s about it.
Call me overly optimistic, but we do seem to have it pretty good when it comes to reliable engines.
I think where the engine is used has a lot to do with whether its a pass or a fail.
–The GM 2.8 V6 was acceptable in smaller cars like the Z24, but in the S-10 pickups and Blazers…what a turd! They even tainted the first few years of XJ Cherokees and MJ Comanches with this abomination. PN got a lot of miles out of his, but from what I hear that’s the exception not the rule. I know several people who had to do a LOT of work on these well before 100K miles. And power….WHAT power? Youd have been better off with the AMC derived 4 cylinder in those Jeeps. Even with a OHV design, it was among the most powerful 4 bangers you could get in those days.
–The Jeep 4.7 V8 was a rockstar in the Grand Cherokee and Dakota. Pretty competitive in the Durango, even. But in the Ram….not so much. 150 or so less hp than the first Magnum Hemis and worse mpgs. Just mismatched to a larger rig. Why the Avenger and Sebring coupes weren’t rwd with top variants using that V8….Ill never know.
–Mopar 3.8 V6. In the minivans, this was a solid motor and with plenty of power. But in the Wrangler….what a turd. The torque curve was all wrong for a Jeep and even though on paper the numbers looked better than the old 4.0, it just didn’t work out in reality.
My parents suffered through two engine replacements in the first generation of the Chrysler K car before they came to their senses and bought a Chevy. I think it was called an MCA jet or something similar.
The Mitsubishi 2.6. Sticking with Chrysler’s own 2.2 was a wise move for K-car buyers.
yeah, the Mitsubishi Astron engine. had some unique features but holy crap, that carburetor was a freak show. and for an engine which had (as advertised) “silent shafts,” it was probably one of the noisiest engines I’ve ever encountered.
Balance shafts aren’t really a big help in terms of noise, although they do keep big inline fours from feeling like cement mixers.
I would go for the Audi High-Compression engine of the late 1960s (1.7/1.8/1.9). 10:1 compression and no electronic control back then meant constant engine knock during the hot days of summer, usually leading to a melted piston or worse, a defective crankshaft rendering the engine useless. High compression also meant horrible NVH, especially at high revs. When Audi tried to correct the issue by lowering the compression, they found out the OHV design was thirsty and gutless. Unfortunately noiselevels remained the same.
Well, a few caveats – I’ll just stick to US manufacturers as I’m not that familiar with others. And I’ll highlight engines that were fundamentally flawed through bad engineering rather than equipped with bad components (Cadillac 368 V8-6-4 being an example of a good engine made bad…..).
– Vega 2300: For all the reasons already addressed
– Ford Escort 1600 CVH: Timing belt good for at most 60K miles in an interference engine – resulted in Escorts being selected “most likely to be found out back of the garage”
– Olds Diesel pre1981 – though the 1981 and up were much better
– Ford Essex 3800 V6: In a word, head gaskets…..
– Mid 70s GM 3800 V6s with uneven crank throws: mobile massage chairs…….(but later developed into a great engine)
– Cadillac 4100 V8: Chased more loyal Cadillac owners away from the brand than the 80 Seville Bustle-back…..
– Chrysler Maserati TC 2.2L Turbo: One word – Kaboom!
Citroen flat 4 1970-1984 RIP. It will burn oil and its camshafts will wear. It will rot its exhause manifolds through (both sides but especially the awkward one on the r/h side). It will also rot the heat exchanger pipes, the inlet manifold pipes and the bottom of the carburettor hotspot. All at different times. And you cant get at three of the plugs without double jointed wrists or get a timing light on the flywheel without using a mirror.
Oh, and in 1015 cc form it’s a completely torque free zone
Being a Citroen the engine design was completely seperate from the vehicle. It should have been clearly labelled ‘Not for Use With Petrol/ Do Not Install in a Motor Vehicle’
This is a seriously good thread ~
Lots of interesting replies and quite a few that simply make no sense , folks who talk trash about a thing they clearly know nothing about .
Notice I say little about many engines here , only what I know and have worked on / owned / driven .
If I’m correct , I am to under stand the robust 368 CID V-8 in my 1980 Cadillac Hearse is the same as used later in the awful 8-6-4 Caddies ? . I didn’t know that although I did watch a buddy suffer through a horrible brand new 8-6-4 , mostly it ran 7-5-3 and drove him batshit , the Dealer was unable to fix it .
I also learned the hard way that not everything Toyota is good ~ ’91 V6 Camry , apparently those engines are toast after 60,000 miles , oops .
-Nate
@ Nate
IIRC that is the same 3.0 (3.slow) that is in my 95 4runner). There was apparently a head gasket problem that caused the exit of that engine after about 6 years. On the good side, when the head gaskets were modified by a factory recall they lasted well. If my truck is a good example they were still slow. Other weak points would also be the aforementioned water pump under the cover with a 70k mile timing belt. On the good side it is a non-interference engine. I now have a 205kmile example in my driveway that runs very well. I have a CEL that sometimes comes and goes (have yet to find the cause) but it runs very well.
Nobody mentioned the Nissan NAPSZ engine series (2.0-2.4 AFAIK). They were a great engine that mated an aluminum head with a cast iron body. 4 cyl with 8 plugs. I owned two trucks with that engine (81 2.2 and 87 2.4). They ran beautifully until they overheated. The weak point was that by the time you knew you were overheating it could possibly be too late. It would be on my best engine and worst engine lists. Loved it when it ran well and lamented it when it blew that very thin head gasket.
Btw my experience with the Ford 300 six does not agree with others here. Extended Ford van. 15-17 mpg and worked like a dog. Preferred it to it’s main competitor the Chev 292. I guess truly YMMV.
Lee ;
The Toyota V6 having issues surprised me because ‘ everyone ‘ knows and loves Toyotas…. I didn’t pay enough attention to discover they were talking about the myriad four cylinder ones until far too late .
The ’91 Camry ran fine and had sufficient power (nothing extra !) and until the temperature gauge headed North on that hot day , it was right as rain .
It came to me with a brand new radiator and had been Woman owned so no hooning etc.
I replaced the engine with a clean low mileage Japanese takeout that had good compression and even before we cleaned it , was dry and tight…
New factory cam belt and water pump were added along with way more seals , sensors valves and things than I realized Japanese cars ever came with , when finished it once again ran fine but only lasted about a year before violently over heating again , I wasn’t driving but that was that ~ $3,700 flushed on a $1,000 car for one of my Foster boys , I shoulda bought him a crappy old dented Toyota pickup for $800 instead .
My buddy got a $500 Nissan ?720? pickup with the fabulous NAPS-Z engine because ” the Mechanics can’t make it run right ” ~ I told him to grab it and bring to me , not surprisingly the Barrio ‘ mechanics ‘ had mixed up the _eight_ spark plug wires , it took me a short time to sort that out and do general tune up , what a great truck . after a year or two of new house hauling he gave it away to a seriously poor old man relative who last time I checked , was still driving and loving that truck over TEN YEARS later .
Ran like a top , original black paint we polished and waxed to a mirror finish
-Nate
The 8-6-4 engine is still a good robust unit. You just have to deactivate the cylinder shutdown and have it run on all 8. This is very well documented and covered on any Cadillac forum.
What were the marketing department thinking when they drew that ad up? It’s cheesy and corny and all sorts of wrong.
Didn’t Don Draper write that?
Sounds like him. Big words to impress and then hints at the truth with the talk of aluminum foil.
I don’t think the post 1965 rule is set in stone so here is Lincoln example
1936-1948 V12 Lincoln…have heard nothing but complaints about this engine
from wiki
“it was more like a “12-cylinder Ford” than a classic multi-cylinder powerplant in character. And it was not without problems. The main ones were inadequate crankcase ventilation that caused rapid sludge buildup in sustained low-rpm running, aggravated by poor oil flow, plus too-small water passages that led to overheating, bore warpage, and ring wear. To a degree, some of these maladies were dealt with during the Zephyr’s first year, and Ford improved the engine by adopting hydraulic valve lifters for 1938 and cast-iron heads and oiling improvements for 1942. Yet this V-12 never shed its reputation for service troubles, though the postwar versions were actually quite reliable.”
My experience of the Imp was that it was not so much the engine itself that was the problem but what was going on around it. The radiator was mounted at the front of the car and water was piped to-and-fro from the rear. Something that I am sure was fine at pre-production stage – but when everything got furred up in later years led to chronic problems of overheating. Sure this thing can be fixed with thought – but in period users often did not bother. Automobiles need a certain amount of ‘foolproofness’.
Those are not on the list yet but I have my doubts about the recent trend of miniature turbocharged engines with bike-like hp from Ford, VW, Citroen and others… How long before the problems start?
Doesn’t matter though does it? My guess is they’re actually going to last really well with little maintenance for quite along time (1o or 15 years maybe?) but when they go, the repair cost will be so high that they will be immediately scrap. But we’ll all largely be electric by then, so it will make good sense to just bin them. Good motors though, so the few that survive the great dying will be highly collectible in 50 years.
Here are a few big ones everyone left out
Cadillac Catera 3.0 V6 – Weak timing belt in an interference engine.
BMW M60 – Nikisil Cylinder liners wore away
Porsche 996 and 986 Motors – IMS Bearings took out almost all of these. My father’s went at 30k miles.
Chevy 2.2l four. Predessor to the eco-tech Truly terrible..
VW W8, 2 v4’s that don’t want to be together
BMW m70 V12- Two inline 6’s sandwiched together with two separate engine computers. Didn’t work well
Ford Powerstoke diesel from the 2000’s
Not quite true re: the Porsche M96 engine family. The class action indicates 10% max failure rate, (still horrendous, I agree, but hardly “almost all”). MANY were covered under warranty and even more were covered well past warranty. For years now the fix has been to replace the bearing with an aftermarket one and consider it a wear item to be replaced with every clutch job. Even if done without ANY other work at the same time, it’s a $2000 repair at a good shop, when done in conjunction with the clutch etc, it adds around $800 for a reputable kit. Some have done it as a DIY for under $100 in materials. $2000 is a huge amount if you’re driving a Civic, if you’re driving a car that was $50k-$100k a decade or more ago depending on versions/options it’s not unreasonable. It’s unreasonable when people buy them used and don’t have any maintenance/repair budget. In the end, once a buyer is educated, these cars make fantastic value propositions relative to their power/handling/everyday usability and everything else. By the way, the first few years of 997 and 987 were also affected though to a lesser degree once Porsche went to the second redesigned bearing in or around 2005.
10% is horrendous, and I believe is a great underestimation, many owners put only a few thousand miles a year on these things which means the failures don’t happen till long after the warranty expires. The number is probably 30-40% of cars that didn’t get a new IMS preemptively. Many owners sucked it up and bought a used or rebuilt engine for 15-20k. Porsche never stepped up to replace engines under warranty, the class action suit was filed for that reason. Boxsters also had issues. The 996 is nice car and a very good value used because of this black cloud over them. Just need to make sure the IMS has been replaced before you buy one. It was most definitely a design flaw of an under-specced bearing, not a “wear item” GT3 and Turbos had a better bearing that wasn’t prone to failure. As far as I know the improved after market replacement IMS don’t fail.
I didn’t say the bearing IS a wear item, I’m saying it should be treated as one, the designer of the most popular replacement bearing (sold by LN engineering, developed by Jake Raby) suggests that as well. There were three designs of the factory bearing on M96 engines, the newest one (2005 or so and on engines) is significantly more robust than the older ones.
If your engine went out under the warranty, Porsche did cover it. The class action came about due to the numbers of affected units and the quantity of people that had run out of warranty due to time, not mileage. If they didn’t cover it it was most likely due to other reasons, i.e. an inability to provide proper service documentation. Porsche never admitted that the bearing was the issue, but did take responsibility for failed engines within the warranty time frame.
Of course the Boxster had issues as well, the engine is the same design, just lower displacement. The Turbo and GT3 have a completely different engine design, the IMS bearing in those engines is different and oiled in a much different (better, more expensive to manufacture) manner.
Apparently driving style is one of the main determinants of failure, counterintuitively the cars that were babied or driven only for low mileages appeared to have had the most failures. Driving it at higher engine speeds and longer distances appears to mitigate the issue.
My uncle had a Catera. The timing belt snapped a day or two before it was scheduled for a recall to replace it! He was idling at a stoplight when it broke. Consequently, the dealership decided the engine wasn’t that badly damaged so they opted to overhaul it instead of replacing it. Fearing more trouble ahead, he promptly traded the car. (I presume he would’ve kept it for awhile if they’d put a crate motor in instead.)
I was surprised no one had mentioned the M60 before now. Though that might be because there are basically none of the Nikasil versions left, most of them having died and early death and having been warranty (or even post-warranty) replaced by BMW with the corrected Alusil version.
Here’s my list from both personal and professional experience running a used car dealership since the early 90’s.
1) Olds 5.7 diesel – yes it can be argued that many didn’t understand the diesel engine and that GM finally improved it by 1981 with the water separator but early examples of these engines were simply a disaster with failure rates very high. The problems this engine had could fill up a page and are well documented
2) Cadillac HT 4100- another V8, this time gasoline, that was rushed into production ahead of schedule because of unrealistic government and cafe demands and GM’s dumb policy at the time of no gas guzzler tax. This motor, like the diesel, was a ticking time bomb waiting to go off and never should have been introduced as early as it was in such large heavy cars.
3) 2.3 liter aluminum Vega 2300 motor- it’s oil use is legendary. So it’s it’s short life span
4) Toyota 2.2/2.4/3.0 and 3.3 liter V6 engines from the 90’s to mid 2000’s. Horrible failure rates on these engines with the sludge problems saw loads of customers with failed engines on there hands ranging anywhere from 50K to 100K miles without much warning. Just look out for sudden oil use and the tell tale white blueish smoke upon startup. I have heard many of them tick until temperature is reached. I remember going to our two local Toyota dealers during this time period and seeing no less than 5-6 engines every week getting swapped out with the cores sitting in crates behind the shop area.
5) Ford 3.8 Essex V6- Ford’s answer to Buick’s 231 V6 which in itself was a bad engine from 1975-1987 in carbureted form. Head gaskets, warped heads and weak bottom ends were the order of the day and we saw many blow up soon after the heads gaskets were done
6) Buick 3.0/3.2/3.8 V6 engines with carburetor from 1975-1987 era- these were crap engines in many ways ranging from weak oiling systems to rough idling in non even fire trim to oil leaks galore. getting on of these motors to last to 100K was a real challenge but the 1985 on up versions saw improvements to the oiling system and front timing cover which reduced leaks. The real improvements came when the 3.8 SFI motors followed by the 3800 came out
7) Chrysler 2.7- known as the sludgeomatics- these engines were also a nightmare for many an owner that didn’t use synthetic oil and change it religiously every 3K miles. Engine swap outs were very common on these
8) Triumph Stag V8- Just a disaster from the get go with bad materials, design and quality- or just bad everything
9) Prosche M96 engine family IMS bearing failures, oil leaks, cylinder head studs for years 1975-1989, mechanical chain tensioner failures of pre 1984 era, premature valve guide wear causing excessive carbon buildup in the secondary air injection ports which means not passing emission regs.
10) Early Mazda rotary engines V8 gas mileage combined with Vega oil usage was a dreadful combination
Honorable mentions-
1) GM Quad 4 pre balance shaft upgrade
2) VW Mexico engines such as the 2.0 R4 as used in the New Beetle/Golf and Jetta -old low tech and high oil consumption are the joys of these engines
3) Mitsubishi 2.6 and 3.0 engines sold to Chrysler- bad heads, blown gaskets, chain adjustments, leaks, ticks, knocks. The failure rate of these two engines during the 80’s was astronomical. The early to late 90’s version of the 3.0 improved to rate and average mark however.
4) Chrysler 2.2/2.5 engines- pin knocks, head gaskets, cam failures and poor block castings, frequent sensor failure and very weak motor mounts causing premature axle shaft failure and oil leaks are common
5) The PRV joint venture V6
6) Ford Powerstroke diesel from the 2000 era.
Good list. But the Northstar didn’t make the cut?
Chevy 2.2? You can’t be talking about the Cavalier 2200 engine because those were a long lasting tough mill with reasonable mileage. Mid 1990’s has defective head gaskets from he factory up until 1997 but the later 1998 on up 2200 has been nearly bullet proof for anything we sold it on.
One example that barely falls outside of the 1965-up definition is the 1961 Studebaker OHV version of it’s Champion six. That one developed a head-cracking problem was likely one of the Post Office’s reasons for replacing it’s fleet of Zip Vans years ahead of schedule.
The Chrysler 2.7 and Ford PowerStroke 6.0 seem to be the worst of the modern ones. I have also heard some bad things about engines in modern Mazda CX-7s, but this is all hearsay.
Here is my list, a rather late one, coming from someone with a garage background:
(from worst to best)
1. The Vega 2300.
2. GM 5.7 diesel.
3. Chrysler 2.7 V-6 Sludge-o-rama.
4. Iron Duke. Gutless and unreliable at the same time.
5. GM Northstar. Just no excuse for this.
6. GM HT4100. GM should have never done this.
7. GM Quad 4. Rough, noisy and cracked heads.
8. Ford Essex 3.8 for eating head gaskets.
9. Ford 2.3 Lima, which I always hated for being gutless.
10. Early odd-fire V-6’s from Chevrolet and Buick, they were rough and gutless.
The Iron Duke was certainly an NVH delight–like having a thrashing blender in the passenger compartment. BUT, having had four of them, I can say they were reliable. Unkillable. Believe me, I tried.
And yes, absolutely gutless. But no worse that other inline 4s of the time. Well, American inline 4s. The 997cc A-series in my 1962 Morris Cooper really isn’t that far removed on power, at about 40% the displacement.
The Iron Duke being “no worse” than other inline fours? Well, have you ever driven a Honda of the era? Or a Camry?
Both my father and I had AMC Concords with the Iron Duke and neither of us ever had an issue with them. Yea, they were a little ( 🙂 ) rough, but they were quite durable and capable of some pretty impressive fuel economy. Both of our Concords had sticks and would easily get 32 mpg on the highway.
So the answer is “no” then.
Perhaps you missed the line “Well, American inline 4s.” Next time, I’ll try to highlight it for your reading ease. In any case, your “unreliable” statement is just that.
The tech IV may have been gutless (what wasn’t in the 80’s 4 cylinder wise?) but unreliable. I say bull to that statement. Noisy prior to 1989. Sure. But hardly unreliable. It’s possible the 1970’s version of this engine wasn’t to hot but the 1982 on up TBI 2.5 was a very strong reliable engine with more examples than I can remember with 300K plus miles still running strong. The rare few Tech IV’s that blew up were mainly from severe owner neglect and high mileage.
There’s a certain faction among auto-aficionados who dislike Pushrod I4s as a category.
The good examples aren’t bad engines given their limitations but many people think every I4 needs to be a DOHC 16V unit with a 7000 rpm redline.
Wow, that’s a lot.
My personal non-favorite is the Chev 267 small block which took one of the best volume engines ever built and rendered it a torqueless mess. (Of course it was still reliable so it doesn’t get full marks for terribleness)
A bit off topic, but I’ll nominate the Honda CX500 motorcycle engine. Conceived during a time when Honda could do no wrong with motorcycles, someone asked, “Hey, why don’t we build a single pin V-Twin with 4 valves per cylinder that revs to 9000rpm? And while we’re at it, we’ll turn it 90 degrees so it works well with shaft drive?
Well, there wasn’t room for a 6th overdrive gear with the engine turned sideways, so you needed all those RPMs for highway cruising, at which point the unbalanced engine forces buzzed the whole bike relentlessly. The charging system was in a hot location at the back of the motor and the timing chain tensioners didn’t last, both of them engine out procedures to replace. Case seams were vertical so they leaked oil like a British bike, and being a top heavy motor they were harder to handle when stopped.
I owned two (primarily because they were inexpensive) and luckily never had major problems but I never liked them much and both times they were gone once I could afford something better.
You never had problems because they were amazingly reliable bikes. The only bike that ran longer was the Goldwing.
RE : Honda CX500 Motos :
‘You never had problems because they were amazingly reliable bikes. The only bike that ran longer was the Goldwing.’ .
Just so ~ even my Son who’s collectively known by the entire V.J.L.A. as ” a one man wrecking crew ‘ couldn’t kill one and God knows , he tried .
They had poorly made nylon fans that simple fell off their steel hubs causing over heating @ idle .
And bad alternator stators that could only be accessed by removing the engine then splitting it away from the tranny…. ugh .
-Nate
The 267 was indeed weak for a V8, but as you noted, the reliability was there. There have been plenty of engines with low output per displacement, especially in the mid 70’s through mid 80’s, so I think that would leave it off the list. But that’s just me…
Hold up right there. Let me ask a question… What makes a bad engine?
Is it low durability? I nominate the Colombo V12 from Ferrari.
Is it poor NVH? I nominate Mercedes-Benz’s OM617.
Is it limited bhp/liter? Cuz just about any early American V6 is laughable. And forget about later Cadillac 500 V8s.
Seriously. The self destructing Alfa V6 stirs my soul. The NSU Ro80 sings and screams and makes its car one of the most fun to drive German FWD in history. And the Trabant engine was unquestionably the ne plus ultra of engine for the environment it was built in. The Trabant is one of my favorite cars period. Not refined or fast or fun. But the engineering is nonpariel.
The OM617 in NA form was noisy, shook the whole car, you could feel every ignition through that gazinta steering wheel. It also is known for surviving a millions miles or more of caning. So is it a bad engine? You tell me.
The Ro 80 engine was unfortunate because it was really a case of just not doing enough preproduction testing. The apex seal design was really very clever; NSU just ended up in a situation where they were relying on engineering projections rather than real-world testing in selecting materials. The later ones were much improved, but as per usual, the damage was done by then.
Yes, the Ford/Navistar 6.0L Powerstroke! Too many issues to list here, typically last about 60,000 miles before some mechanical catastrophe takes them out. Made me forget all about the Olds 350 diesel. Unlike the Olds, the equally failure-prone 6.0L is difficult to service and expensive to repair. Ford actually recommends removing the entire cab of trucks so equipped to access the engine. In my opinion, the worst diesel engine yet devised. There was (briefly) a 4.5L V-6 derivative that was equally bad.
307 Chevy anyone?
The 307 in parents’ 1968 Bel Air wagon was one engine that didn’t blow up before they were ready to trade it (this one at roughly 87,000 miles iirc). They were GM buyers all the way up to 2009. After seeing all the strandings, major disassembly jobs needed, and should-be minor problems that the dealer would not or could not solve, over the years… I haven’t owned a GM myself since the ’70s.
So, what was the weakness with the 307?
IIRC, the Oldsmobile 307 regarded as being gutless. The Chevrolet 305 was considered to be “spunkier”
True, but that’s the Olds 307. I think the nomination was for the 60’s-70’s era Chevy 307. (I have no idea what its issue was though.)
And while the Olds 307 was down on power compared to the Chevy 305, it was at least relatively smooth and quite reliable (other than the rat’s nest of vacuum lines which were prone to leaks).
I had a ’77 Bonneville with a 301 Pontiac engine… I regularly got passed by glaciers…
Were the blocks “soft”? I think perhaps it replaced the 283 which was a great engine may have something to do with it…
For some reason I like 283s even though the blocks were made of mush. Must be nostalgia.
They’re neat – smooth and like to make revs. They “feel” different to a 305 or 350.
Yeah- I have a couple of ’em. They sure run nice but even with proper maintenance they aren’t good for 100,000 miles; noticeable signs of bore wear show well before then. Mushy cast iron blocks.
Had a ’70 Chevy C10 with 307 V8 that was still on the original short block at 161k miles when I sold it. Did have to pull heads around 100k miles to install hardened valve seats due to leaded gas going away. The truck did quite a bit of towing heavy loads. It was using oil at about 500 miles to the quart at the end, though. I have heard that some had soft cams that would go flat, but mine never had that problem.
Here is my worst, and it is from personal experience:
Buick 3.0 litre carburetor V-6. Absolutely the WORST engine ever. Having owned two Centuries with this engine, I can tell you they were made to last no more than 50k miles and they were history. I bought my first Century, a 1984 Limited Coupe, with only 26k on it from the original owner and got 10k more out of it before that POS 3.0 crapped out. The rod knock was so loud that even the dealership was shocked that it had made it there on its own. GM helped with that one, but then it went again after only 30k more miles and I was on my own this time. After finding a junkyard engine, that car never seemed to drive the same and I got rid of it even though I truly enjoyed the size and comfort of that Century. A few years later I was given the chance to buy a friend’s grandmother’s 1985 Century that had about 30k miles on it. I was praying it was either the 2.5 Tech 4, or the 3.8 V-6. But no, another 3.0! That engine ran ok but you could tell it was on the verge of problems so I decided to sell it. It had that strange knocking sound upon starting that I knew was going to be trouble. GM discontinued that engine after only 4 years so you know it was a total dog!
The ironic thing? I still wanted another Century so when the chance came to buy one with the 3.8 SFI V-6 I grabbed it. That engine is one of the BEST GM ever made. So I owned the same kind of car with two different engines, one being GM’s worst and the other their best!
The FWD biased 3800 is one fantastic engine, no doubt.
Searched the comments for the Oldsmobile V8 diesel, multiple mentions already, that one is definitely a major contender for the pile-o’ award. I would like to discuss it, but really there’s absolutely nothing to say about it. Think of anything, and on this engine it’ll be terrible, right up until the moment when the whole thing detonates. Quite frankly this one engine ruined the reputation of passenger car diesel engines in the US for decades afterwards.
The Cadillac 8-6-4 was another bad idea, or rather a brilliantly future anticipating idea executed far too early and badly, but on the upside you could turn it into a regular V8 by getting the control box removed.
Another mentionworthy block is the Chrysler 2.2 I4. Not a bad design at all, but notoriously badly built from the factory, and then instead of fixes they applied turbocharging to it.
The Iron Duke on the other hand is always one of the first that come to mind, but being the complete opposite from the Chrysler block it’s really solidly built and runs forever, but it’s incredibly gimped by design, mostly thanks to the emissions shackles.
emissions shackles????
I need those, can I get them at RockAuto?
They’re right next to the muffler bearings.
And the blinker fluid.
And spark plugs for diesel engines.
Don’t forget the Piston Return Springs…….
-Nate
I’ll pile on the Chrysler 2.7 as well, which has the water pump located BEHIND the finicky timing chain and its prone-to-early-failure hydraulic adjuster. The chain itself might go 200K, but it never gets the chance.
Crosley COBRA anyone? Seemed like a good idea and worked fine in portable gensets but wasn’t up to car duty so Crosley developed a cast iron block and replaced all the leaky COBRAs.
Also a personal favorite is the Lancia Gamma, where turning the steering wheel to full lock when the engine was cold would strip the teeth off the timing belt and trash the engine.
The 3.0 L Mitsu used by Chrysler. The only engine I have owned that had to have its heads removed while I owned it. And everyone I know that had one had the same experience.
Talk about different standards to compare engines–We’ve had a few customers with hemi powered Mopars have a shit fit when they find out they have to replace 16 spark plugs–and the late model ones require platinum plugs.
I worked at an auto parts store twelve years ago, and the one thing that stands out in my mind, was that the engine rebuilder we dealt with couldn’t supply 6.5 diesels due to not being able to supply cores. Something to do with the crank webs cracking?
I could also suggest the GMT800 and up 4.3/automatic…two guys at work have them, and our old shop truck also was a 2005 Chev 1500 with a 4.3/auto.
Stone reliable, but man, zero fun to drive! Geared so high that they were really, really lazy around town, and with overdrive, lazy and shifting all the time on the highway. Not enough power to haul a trailer or a load.
I will say we had 5 different people driving the shop truck trying to kill it, and they never did.
The 4.3 was actually a lot of fun in the S-10. Very nice power by 90s standards.
The 6.5L was O.K. as long as you didn’t ask too much of it. Core scarcity may be due to the fact that all those military Hummers are equipped with 6.2’s or 6.5’s. The U.S. Army must go through a mess of those things.
From what I understand (Which isn’t much on diesels), the regular 6.5s were much more reliable than the turbodiesel ones.
I don’t think I’d call the 6.5 one of the worst engines out there, but the 6.2L- that’s another story. My father had one in a GMC- that thing ate starters and didn’t do well at all in the cold.
We have had two vehicles with 6.2L diesels, a 1984 GMC van and my dad’s 1988 Suburban. They were both gutless but reliable engines that outlasted the rest of the truck.
The 6.5L was unreliable and the reason I replaced my van with a Cummins-powered Dodge pickup. I read recently that there was a casting flaw in the 6.5 blocks installed in every Hummer that would cause it to crack near #8 cylinder. The fuel injection system was also problematic. They also suffered from exhaust manifolds cracking. Apparently good 6.5 exhaust manifolds are almost impossible to find now.
I did hear from someone that both the 6.2 and the 6.5 suffered from cracks in the cylinder heads between the intake and exhaust valves. You could have an engine that was running fine, but if you tore it down for overhaul you’d discover the cracks and now you’d need to source replacement heads.
A lesser known engine may be the Daewoo XK6 inline 6 that was used in the Suzuki Verona…Apparently it had some design input from Porsche. 155hp from 2.5 liters wasn’t all that great and it was less than some of it’s competitor’s four cylinders were making at the time. 0-60 times were slower than even compacts from the time…All of this could probably be forgiven if it wasn’t for the fact that it was probably one of the most unreliable engines designed in the 2000’s. Head gaskets, valvetrain issues, worn rings, and numerous sensor issues would occur (and usually at very low mileages). My friend had an early ’04 Verona that needed a complete engine rebuild at around 50k, and his situation was far from uncommon with these. It’s a shame, because I really wanted to like these back when they first came out, and other than the fact that they were slow they drove very nicely (almost like a poor man’s S80) and had a nice sound to them.
Porsche had some input on the Volvo white block modular 4,5, 6 cylinder engine that they used from the 90s until recently. Early variants needed a timing belt every 20,000 miles, which doesn’t say much about their design prowess. Fundamentally stupid design…later versions are Ok with 105,000 mile changes, but it took awhile to correct the design to get to that point.
I’m surprised no one has mentioned the VW “Wasserboxer”, especially the first 1.9 liter version. Quieter and better heater than the air-cooled engines, but not much power and very prone to head gasket failures and/or head erosion. It’s ironic that Subaru swaps are popular for these …
Simple – the single worst of the modern era is the Porsche M96.
The early water-cooled boxers combine a breathtaking failure rate thanks to a sealed IMS bearing, with a rebuild cost of about $20,000.
At least replacing the Vega engine was cheap.
This kind of counts and kind of doesn’t but still gave GM another black eye. The Chevy engine in the Oldsmobile scandal back in the 70’s. A lot of loyal Olds fans bought cars on the merits of a Rocket V-8 but to their dismay they didn’t get what they paid for because they got a Chevy motor instead. Another crack in the bedrock Under GM.
You can’t really fault the engine (The SBC was a very good engine), but I agree- that was one of the most egregious moves that GM made at the time. Some of the customers didn’t find out until they tried to get their “Olds 350” serviced.
I’m surprised I’m the first to mention (unless we’re only talking car/light truck engines) the Cat 3208. My late father was a lawyer and he made quite a bit of $$$ for his clients suing Cat over 3208 failures.
The Vanagon waterboxer engine was very prone to head gasket failures so not a very durable engine. Almost 350 comments! Is this a CC record? The GM 5.7 V8 Diesel was a real dud, especially the early versions. The Ford 400 small block, my friend went through 2 of those, 2nd was a Ford factory rebuilt, they both blew at around 65-70k miles.
At least in the US they did not have to suffer the Citroen GS. Beautiful car, but totally unreliable from day 1. My dad had one from 1979, one of the last GS before if was changed to the GSA. We loved the looks of the car and the ride…. but somehow in a car which was almost a ten year old design, engineers and mechanic from Citroen couldn’t make it run properly.
It’s a week late. but how about the Audi 4.2L V-8 with the timing chain that costs up to $8000 to fix?
http://jalopnik.com/here-s-why-the-v8-audi-s4-is-an-awful-used-car-1676466510
One that doesn’t really get mentioned but should:
The Suzuki 650 used in the Savage/S40.
It has a faulty timing chain adjuster that can and will work itself loose inside the timing case, which means unless caught the engine explodes with about 10,000 miles.
Lots of info here:
http://suzukisavage.com/cgi-bin/YaBB.pl?board=tech;action=display;num=1176999168
Plus!
It has been known to suffer from premature cam journal Wear:
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1268452150
Plus!
It has a faulty plastic plug in the head, which means after 5,000 miles or so you always smell oil vapors:
http://suzukisavage.com/cgi-bin/YaBB.pl?board=tech;action=display;num=1177184297
I mean, it’s a fun engine and all, but it tells you something about Suzuki’s contempt for their customers (well, at least the customers that bought Suzuki Savages) that they built this motor (with some interruptions) from 1986 to 2019, so THIRTY FOUR YEARS, and never fixed any of these issues. Or maybe it says something about the customers who bought these motorcycles. Either way…
Is this the same engine that is still in Suzuki’s DR650 motorcycle? The early versions of the DR presumably shared the engines with the street Savage, but were heavily redesigned in 1996. The new one has its share of issues and the DR is still in production after 25 years with some subtle improvements by Suzuki. The DR650 (full disclosure, I own one) has a worldwide following, dare I say cult, along with a healthy aftermarket and well-documented fixes for its few minor quirks. Mine is fairly low mileage, about 25,000 but the cam chain and tensioner are just fine.
They are the same size and both air cooled, but they don’t share any components that I am aware of, fortunately for DR 650 owners. I think the Savage engine was effectively half of an Intruder engine, but I’m not sure, and Intruders don’t have the same cam chain tensioner issues either, though details of the bottom end have to be different for numerous reasons.
Joe Yoman above mentioned the Chrysler 2.2 litre fuel injected model. I too had one of those, a 1985, and while it threw a few fuel pumps and a sensor here and there, it gave me 300,000 kms of fairly hard daily driving through winter and summer for 10 years. So, no.
I would nominate my 1996 Cavalier 2.0 litre FI engine. Head gasket failed at 50,000 kms. Along with the transmission. At just 3.5 years old.
I’d nominate my 1193 cc engine in my old Beetle, but that wouldn’t be fair, it had served a long life by the time I came upon it.
It’s interesting that nobody mentioned the Ford Triton V8s in 2015. The one mention of the Mopar 4.7 liter V8 failed to mention that they’re disastrously frangible. The 3.7 liter V6s too. Anything with cylinder deactivation is now treated with contempt by independent mechanics. I suspect it won’t be too long before all the earlier bad engines are forgotten as people spoiled by port-injected anvils from the ’90s and 2000s come to grips with the ephemeral nature of turbo-charged and direct-injected lumps.
Six years ago I nominated the 1.9 Volkswagen “wasserboxer”. I still stand by that choice as the worst engine I’ve owned. And I owned a Vega. And the Vega overheated and immediately started consuming oil. And it overheated because a thin and poorly clamped gasket on a coolant passage into the intake manifold failed, and coolant leaked onto the exhaust manifold leaving no trace, no sign of steam or other warning signs until the coolant was mostly gone, and the coolant temperature gauge caught my eye because it read LOW, on a 90°F day in Portland. So yeah, my Vega was troublesome and certainly the engine was weirdly designed and lots of poor quality stuff, but I think hindsight has been harsh on these cars. Rust, penny pinching on some basic parts, and poor packaging didn’t help either. My Vega replaced a B18 Volvo which was pretty rough and noisy, and much less torquey. My Vega lasted 90K miles before its meltdown and that included quite a few autocrosses, many commute miles, and a wonderful trip from California to the Canadian Rockies. And back. Though the last 500 miles required many gallons of radiator top-ups.
You are a lucky, luck man.
Scroll down a little bit through the below….and I think you’ll recognize that you dodged a silicone coated aluminum bullet with an iron head.
https://books.google.com/books?id=sLL4QK_hHjwC&pg=PA199&lpg=PA199&dq=why+did+the+vega+engine+fail&source=bl&ots=kd4uKrb5v2&sig=ACfU3U2UtJ7f2ON5BkQm-G2VQGzcWmSXvw&hl=en&sa=X&ved=2ahUKEwiaw_ih8ZXqAhUSWN8KHcaODEk4ChDoATABegQICRAB#v=onepage&q&f=false
From personal experience, my top three worst ever engines:
1. Mazda 13B Rotary
2. GM 231 V6
3. Mitsubishi unknown model 4 cylinder POS in my Colt Vista
All three of the above engines blew up for no good reason in cars that were relatively low mileage and well maintained. The Mazda was the most problematic, as nobody would touch a rebuild job on one in the 1980s, we had to rebuild it ourselves, in the street, in the middle of winter. The 231 failed TWICE in two different cars, after which I made sure to only buy V8s – or imports! It was at least an easy swap. The Mitsubishi wasn’t worth the effort and was immediately junked upon failure.
It was great to re-sample all these Comments—-lots of fun to chew on.
I’ll defend Ford’s Lima/Pinto 2.3L, even if some expected more oomph from it. Was its failure rate anything at all like the Vega’s?
As to the Vega Engine ad, my guess is that “and other delights” is referencing the Tijuana Brass LP of not many years prior. Here’s the update, BTW: https://www.seattletimes.com/seattle-news/herb-alperts-whipped-cream-lady-now-76-living-in-longview-and-looking-back/
The Ford 2.3L Lima engine had some kind of design flaw that was enough to warrant a ‘silent’ recall in the seventies. I worked a Ford parts counter during that timeframe and Ford had a kit with specific parts that was routinely used to repair (under warranty) a ‘piston scuffing’ issue on those engines in Pintos and Mustang IIs.
I only saw it mentioned once, but the most recent bad engine has to be the 1.6L four in the 2004-2011 Chevy Aveo (aka Daewoo Kalos). Even when new, they were quite agricultural, slow, and got dismal fuel mileage for a small powertrain.
I don’t know what was specifically engineered poorly with the engine (probably just an overall use of the lowest quality manufacturing material), but it quickly developed a reputation for the exhaust to spew out various colors of smoke, depending on what system was deciding to let go.
I’ve read elsewhere that ’85+ HT4100s were much better, but my step-aunt had lots of trouble with hers in a nearly new 86-7 FWD Fleetwood. I can’t remember now, it might have been the electronics kept failing, but she soon ditched the car.
2004+ Northstars have had few headgasket problems, thanks to better bolts, yet the reputation makes them a good used car buy. The real crime is it took them a dozen years to get it right. The $25 tensioner pulley on the DTS has a tendency to fail before 100k miles and take the water pump with it, an expensive repair due to labor.
It’s unbelievable that one of the most mass produced engine families aren’t mentioned, from 1961 to into the 1980’s, each and every Buick V-6 and V-8 with the front timing cover oil pump are the absolute worst engines of all time. No oil pressure, low oil pressure, knocking rods, wiped out mains, broken crankshafts, etc. Most mechanics who actually work on engines are well aware of all of this. If you own an wrecking yard, you know most of the Buick engines are junk. By the way, Cadillac used a similar design that caused trouble, but seemed to do much better. A tip. If these engines were used daily, they did better, but left sitting any length of time, the oil drains out of the pump, pump looses it’s prime, and there’ll be no oil pressure at start up. The Buick shop manuals all address this and have the method to reprime the pump.