The GM 3800 engine, which came in roughly 25 million cars, in three versions. This is Version II, as one can see, and it had a few shortcomings which could cause slight damage or serious damage depending on luck probably.
So here is everything spread out on my kitchen floor that I will try to get into the car in one day. I have never worked on a GM 3800 much less any GM engine, unlike Fords, so I expect to take a little more time than book in doing the work. Fortunately, with You Tube, there are plenty of good videos showing how to do it in a LeSabre and for many other GM cars.
First task is to remove the gravel guard with all the fasteners underneath in order to get to the radiator drain. Start time 12:00 noon.
Then carefully place some aluminum foil to divert the coolant away from the car.
Remove the three bolts holding the alternator and remove from the car.
With the alternator out of the way you can pry off the heater hoses. Good idea to replace those now older O-rings. I went to the local dealer to buy some and despite 25 million 3800 engines they didn’t have a set. The closet was in Reno, Nevada. Never mind and got them off Amazon (argh) in 3 days.
Moving on one now removes the idler assembly which I believe is also three bolts. With it out you can see those troublesome plastic elbows that can crack and leak. The actual joint were Ok on mine but one did crack on the end.
Next comes the water pump. First you need to remove the pulley. Once that is out of the way comes the water pump bolts of which a few are into the water jacket. Knowing that I placed aluminum foil so coolant didn’t hit the sensors below and cause trouble. Obviously one should use a sealant on all the bolts that go back into the water pump after the bolts are cleaned of the old sealant. Bolt cleaning alone took me an hour to get these clean as well as intake bolts. Another half hour was spent cleaning off all gasket material from the mounting face for the new water pump. Water pumps are easy.
On the passenger side it is time to disconnect a bunch of stuff. I studied up on this since I had never done one before and needed to make sure nothing was missed. Here three spark plug wires and a couple of sensors need to be moved out of the way. That also goes for the fuel injector connectors all around. The fuel rail is held on by two nuts each side so easy to deal with.
On the driver’s side you need to disconnect the throttle cables. Easy. There is a bracket with conduit attached that has to be disconnected and then the bracket moved out of the way. One bolt and one hidden 8mm nut buried away. Of course the 8mm nut, which was difficult to get fingers on, managed to drop down below (argh).
Sensors on top of the throttle body. What happens here is that the throttle body needs to be removed from the car to make room. Of course there is another nut underneath that connects to a bracket that the throttle body is attached to. Easier to get to compared to the other side.
Ok, so I am now ready to remove all the upper intake bolts. After that you lift the fuel rail off and direct to the back side of the engine, gently of course, to position out of the way. Then the wire harness that crossed over the upper intake needs to be lifted up so you can slightly lift the intake and slide it out from under.
Here you can see what the upper intake gasket looks like. Remove it and then take out the bolts for the lower intake. There are two bolts hidden in two of the corners that you need to know about. Those two were swimming in oil. The lower intake looked worse in person than it does here. Once that is out you can see the original GM plastic lower intake gasket which apparently doesn’t play well, over time, with Dexos so they say. An engine could get a leak and not know it until too late.
The lower intake was filthy and when I work on my cars everything must be as clean as possible before it goes back on. Getting this cleaned and then dried took about 1 1/2 hours start to finish.
As the lower intake was drying in the sun I placed the new steel gaskets and end seals in. Don’t forget the silicon sealant in the four corners to prevent vacuum leaks.
Lower intake back in place and torqued to specs.
With the lower intake in it is time to remove the small EGR pipe seen here. The major issue with this is that the air gap between the metal pipe and the plastic intake isn’t enough to keep the plastic from hardening and then cracking. On either side of the hole in the intake is a water passage and you can see two holes on either side of the EGR orifice. When they crack then water into the engine again if you are unlucky. So the newer upper intake assembly, I bought some years ago, has a narrower pipe and the intake has a protective metal sleeve inside as added protection. Also has the metal elbows to replace the plastic ones earlier.
However, Houston we have a problem. See what I see and both of the newly supplied replacements were the same size. Apparently pre-99 intakes used a pipe with a 0.750″ diameter while after used 0.625″ (ARGH!!!!!!). Just you know what great and nothing I can do about it. Not sold separately not that I would wait and leave the car as is. The car must get back together as it is needed a week later. I showed Tom, on the USS Hornet, and asked if he could put it on the lathe and cut it down to the correct diameter and he said yes. So it will be done at a later time. Now my decision was which upper intake to use for now. The old one had 0.1875″ clearance around the original pipe while the newer upper would have only 0.125″ clearance. So I went with the larger clearance for now.
With the above decision made I put the thermostat housing, with new thermostat back in. Now you need to lift that harness out of the way to slide the upper intake in from the right. Then it is a matter of torquing down to specs in two stages and then replacing the fuel rail after new O-rings, replacing brackets, sensors and assorted cables and wires. This now goes really fast since I have been through it once already.
On passenger side you can see the new water pump, new idler assembly, alternator and new belt in place. You can also see one of those metal elbow replacements. Time of finish 9:30 PM and I was beat and sore from all the leaning over not to mention starving. Nonetheless, it was done. I’m not concerned about the EGR tube as I know I could get the upper intake out now in under 20 minutes and have it all back together in one hour. Unfortunate that the Series III aluminum upper intake does not transfer directly over to a Series II. Anyway the car needed to be done as it is the long distance car and was needed to travel from the Bay Area to Valencia (Six Flags for wife and son) the following weekend. The engine ran smooth as silk for the almost 700 mile round trip down US 5 and then up CA 99 to visit family and then back to the Bay Area. This 2004 3800 II now has just over 63,000 miles.
Thanks for taking us so clearly through this—I’m happy that end result was reliable/manageable (re the EGR-tube thing). Unlike some super-elaborate wrenching shown here at CC, this sounds like a job I could *almost* find the nerve to do, once I’d mastered all the how-to videos and such. Congratulations!
Wow. Just wow! I’m so glad there are people like you who can do this stuff. I was finished after the first step of just removing those pin thins and that plastic cover! haha.
Although the 3800’s had a few week spots, it’s still one of the best. And in a Buick sedan at that. Great engines in a great car.
Though it wasn’t shown on your photologue, I do hope you disconnected the battery first.
I’ve personally seen what can happen if the main accessory wire ( like from the alternator ) grounds out against something. If you’re lucky, you’ll have a wiring harness melted to a glob. If you’re unlucky, you’ll have your car melted into a glob.
The battery on these cars is under the back seat and out of shot. Fortunately wrench access is good for the side terminal battery with an 8mm or 5/16″
I have been doing car work for so many decades that I don’t even think it since it is such a basic habit.
This is more familiar ground than your last post, we replaced the front cylinder head on our 2003 LeSabre a few years ago which required pulling the intake and replacing gaskets but it’s still running the same water pump.
For a trip into the bottom end and a good example of gelling Dexcool check out the I Do Cars tear down of a 3800 Series II from a Pontiac
The car this engine came from got a replacement engine and is still running, and our LeSabre is at 216.000 miles having literally outlived the first two owners
1) There is no back up safety clip on the fuel regulator.
2) I have replaced many intakes and 2 stovepipes were included in the Dorman kits, though it has been 5 years or so since the last one.
3) The bearing in the idler pulley is a 203SS.
4) The O-rings on the heater hose stubs are nothing special and can usually be obtained from an auto parts store. Viton O-rings are preferred. Make sure O-ring groves and mating bores are clean.
1. No safety clip present, and since this is the first time the engine was worked on, that means a factory omission.
2. Graywerks supplied the intake along with 2 large stovepipes.
3. The stovepipe being modified below this past Saturday.
Thanks for this. I’m new to the Buick 3800 engine. I’ve got the factory shop manual, but I haven’t done anything with my engine yet. I’ve got to fix a minor oil leak situation.Then it will be belts and hoses and the intake manifold gaskets. I had read about those elbows and the EGR pipe, nice to see them in person.I have replaced two intake manifolds on my ’96 Mustang 4.6 so I’m familiar with fuel injectors and fuel rails.
That engine was mounted north south here not east west which didnt remove any of these issues and created another problem, the plastic heater valve and inlet are right next to the left exhaust manifold so get fried and add to coolant leaks, great engines but asnother 5 minutes thought at the design end wouldnt have hurt, Better engines than the screaming rattle trap that replaced them
Great post and details/photos. I had a 93 Pontiac Bonneville SSE with the 3800 engine. I agree it is a great motor, but I got bit hard by the plastic coolant nipple going into the head from the water pump hose. I was lucky I was only going to the local neighborhood bagel shop and when I came out I was bleeding coolant … I had to limp home without overheating, requiring several stops to shut the car off and waiting to cool down. The plastic nipple broke off and the water pump was shooting coolant all over the engine … if this had been on the highway at speed, the likelihood of catastrophic overheating was high unless one was religiously watching the temperature gauge. The replacement coolant head nipple I got from the Pontiac dealer was metal. Yet another GM disappointment … what was probably less than a dollar cost difference between plastic and metal for that part, and of course in true GM fashion they went with plastic for a critical engine cooling component keeping the engine safe …ugh!
Thanks for a great write-up. I’ve done this job multiple (5+) times over the last 20 years. Before the reduced diameter stovepipe was available in the aftermarket, I used to make my own from two different diameters of stainless steel. Also sleeved the upper manifold using a piece of stainless pipe and JB weld. That saved the cost of a new manifold. Never had any issues after that.
One thing I always did after the job was to change the oil and filter, in case coolant made its way into the crankcase.
The Series III engine that I had in my Lucerne went back to the aluminum upper manifold, which I also had in my 92 Bonneville.
Yes, it was irritating to know GM went back to an aluminum intake in the Series III and it wouldn’t back fit. So they use a plastic intake to save a few dollars, weight not so much and not their thinking anyway, yet cause some owners massive repair bills if not new engines.
On my 98 Bonneville, I saw a class action lawsuit on these manifolds and filed a claim. Eventually got a check for $500 from the GM unit that was in charge of liquidating the “old GM” assets after bankruptcy.
It’s too bad about those intake gaskets; they’re one of the few shortcomings I’ve heard about with the 3800. Once you advertise long life anti-freeze, people read that as lifelong, which isn’t the same thing.
I always forget about the balance shaft floating up there in the valley – no wonder those engines are so smooth.
I have had two of these engines, one in my ‘97 GTP, and the other in a ‘98 Regal GS that my ex bought from my father. I never had a lick of trouble with either of them in this regard, but IIRC, the 3800 Supercharged Series II had a metal intake manifold.
My (ex) wife was a tech at a Pontiac dealer at the time and told me how lucky we were to have the boosted variant because of this. She had done several of these where she worked, and it was always on the normally aspirated car, never one of the supercharged cars.
The only time her Buick ever overheated was one time when I was driving it, and the serpentine belt broke. Fortunately, I was only two miles from home and was able to limp it there stopping once or twice to let the engine cool off.
I’ve never had to do a water pump, but the rest of this all looks very familiar.
I had a ’95 Olds 98 that I put the improved upper intake/EGR on.
Next was a ’96 Olds 98. That one already had the intake done, but needed the idler pulley replaced, so got the metal coolant elbows.
The last 5 years, I have had a LeSabre that is a twin to yours. I got it with 145K. Again the upper intake had already been taken care of. I did have to replace the heater core, so at that point replaced all the hoses and the elbows. Around 175K a couple of rod bearings failed. I put a used engine in with 110K and that one got a new upper intake and new gaskets for the lower. The car is now at 231K, so 166 or so on the engine. When I changed the oil last month, there was evidence of a little oil seeping out somewhere, but not enough to drip on the garage floor, so that’s good enough for now.
Assuming nothing blows up in the meantime, I will probably do that shift kit in the Spring.
I own a 99 Lesabre with this engine, and have never had any major problems with it. My parents bought the car in 2012 with 104,000 miles, and it now has 134,000. I drive this car about 6 times a year to visit relatives in the eastern Tennessee mountains (approx. 300 mile round trip), and it is an absolutely fantastic highway cruiser with good gas mileage, even on those mountain roads. This is probably the best car and the best engine I have ever had.
By the way, is it just me, or has anyone else had an issue with accessing Curbside Classic on their phone lately? I have not been able to get it for the last week and a half. I hope someone out there can tell me what the problem is.