COAL: 1986 Mercedes Benz 560SEL – The Banker’s Hot Rod

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– Posted on October 22, 2017

I guess you could also title this “Same song sung in a different key”. I enjoyed the 1988 300SEL a lot, but who wouldn’t jump at the chance for the same supple and quiet ride, with more power; a lot more power?

The 300SEL had the 3.0 liter version fairly new M103 Mercedes straight six that had arrived with the new W124 in 1985. It had fuel injection, but still just a single cam and 12 valves. It was set up for long life and smooth, quiet operation, and an optimum balance between top end power and torque, making 177 hp if my sources are correct. But with a curb weight of 3400 pounds give or take, it was sufficient in the S-Class, and undoubtedly livelier in a lighter 300E.

The 560 SL, SEL and SEC featured a 5.6 liter SOHC, 16 valve engine good for 238 hp in USA spec. It had a pretty healthy torque curve, peaking at 288 lb.ft, at a pretty modest engine speed, which gave it almost American-style V8 grunt. While the horsepower rating may not sound great now, at the time, it was quite ample with the lower weight of the S-Class of the day. In addition, expectations of the driving public were just generally lower in the post-Malaise years. Remember the 101 hp of my BMW 320i? What would seem laughable today was pretty peppy for the 1980’s.

The 560SEL was good for a top speed of 142 mph, which was excellent at the time. And its 0-60 time of 7.0 seconds and quarter mile time of 15.6 seconds were nothing to sneeze at either. Just put the hammer down hard.

As Paul explained in the comments to the 300SEL article, the six would get up and go if prodded to do so. Mercedes uses a “kick down” switch under the accelerator pedal of most 1960’s to current gasoline, automatic transmission vehicles. The four speed automatic would start in second gear unless the pedal was depressed hard enough to activate the switch. And you have to actually hit that switch to spur aggressive downshifts. Just “flooring it” without depressing the electrical switch doesn’t get you much initial action, like would result in a Cadillac or Lincoln anything. And that, I think, explains why a lot of luxury buyers were put off by Mercedes and BMW experiences in the 1980’s, and swept into the waiting arms of Lexus.

Most Detroit cars of the time, at least, had a very light throttle to simulate oodles of raw power that really didn’t exist. The Mercedes’ by contrast took the opposite bent, with a heavy accelerator that took some pressing down. But the power was still there in reserve when the Americans were out of breath. My 2016 Lexus seems to strike a happy medium; a lighter throttle effort on the drive-by-wire pedal for sure than any Mercedes I have driven, but not touchy and almost devoid of resistance like my grandmother’s 1984 Bonneville. It’s 5.0 liter 4 barrel would chirp the tires at will since the lightly sprung accelerator was basically an on/off switch. But passing at speed on a two lane road? Forget even trying.

In 2003, I stumbled upon the 1986 560SEL (in the featured anthracite grey) at a local buy here, pay here lot, much like this picture. It was really a tire and battery place, but they had a lot of cars on offer too. I passed them from time to time the next town over, and they are still in business though their fare has gravitated to jacked up pickup trucks. But at the time, they frequently had interesting imports. The 560 was on the grass by the road, with “CASH ONLY” on the windshield. That sounded like something right up my alley! Cash only at a BHPH must mean it is distressed in some way.

It had 130,000 miles and upon closer inspection, it was cosmetically very good, too good actually. As you know by now, I like my rescue COALs to run well but need cosmetic elbow grease. It had glossy, deep paint with obvious areas of work and repaint, but still nice. A light grey leather interior that was clean and intact, with burl wood that was dark and glossy, not faded and cracked. Really, it needed nothing cosmetically but a good bath. The owner was friendly and talkative. He bought it from a small local BMW/Mercedes new car dealer (since closed) as a trade-in they didn’t want about four years earlier. He had sold it at the BHPH twice, and repo’ed it both times.

This last time he took it back, though, it had squealing brakes, the heat was barely getting warm, the stereo had been removed, and the antilock brake light was coming on every so often. He had put front pads and rotors on it, but the other problems were more than he wanted to spend. He had been quoted $1000 or more for a replacement ABS unit.

He didn’t want to state a price. “Tell me what you’ll give me cash, as is. Everybody coming in here wants it fixed, or wants me to finance it again”. I offered him $2,500.00 cash and he accepted. That was probably all gravy for him. After selling it twice, with large BHPH down payments and 48 or so monthly, high-interest payments, he had probably made a handsome profit already.

I knew the radio would be a quick and easy fix with Crutchfield. The lack of heat I hoped I could fix myself with a new duovalve (this would be the third Mercedes in a row with that issue). The antilock brake light concerned me, but we all drove cars for years without antilock brakes, right? So if it can’t be fixed cheap, I’ll just drive it as it and put black electrical tape over the angry light. The lights in a neat row lent themselves to this “fix”.

The glovebox held lots of receipts and the stamped maintenance booklet; until the BHPH lot, it appeared to have been a one owner with dealer service by the book up to about 90,000 miles. The new radio from Crutchfield went in without a hitch. The new duovalve, in a stroke of luck, sure enough made the heat nice and toasty. The antilock light came on about every time I drove the car, and usually hitting a bump seemed to trigger it. The brakes seemed to work fine, not that I ever activated the antilock feature for sure. It just always stopped on a dime, pretty as you please.

I had also noticed quite a “roar” at times, around town speeds seemed worse than the highway. And, the noise seemed worse in curves as well.

So, the roar is what I was really trying to track down. From what research I could do online, it appeared worn wheel bearings were a likely culprit. But I also was surprised to find that worn wheel bearings could lead to the ABS light coming on. Seems that the worn bearings cause just enough inappropriate / nonsynchronized movement of the wheel(s), that the ABS sensors think the wheels are not moving at the same speed. Therefore, the sensors (wrongly) think there must be a malfunction of some sort.

I approached my local tire and oil place about the wheel bearings. They were willing to install them; they were the old fashioned, cheap, replaceable kind. Even now, they are only $5 or so per wheel, on Rock Auto! None of these expensive hub assemblies like the new cars today.

The bearings made a night and day difference. The car was silent, for the first time. And the ABS light never came on again! It was the bearings all along.

I drove the 560 for about two years, up to about 160,000 miles. It was in such good mechanical and cosmetic condition that I actually traded it in to a new car franchise dealer for a reasonable sum when the next COAL crossed my path. I don’t recall doing much else to it, aside from a set of Michelin tires. I backed into a tree in a dark driveway, but it left no sign of damage to the bumper. I had my only “blowout” ever in this car, when I hit a piece of someone else’s tailpipe in the road and sliced the passenger rear tire clean open.

The next COAL was a departure for me, but was a fun car, and it stayed in the family with a relative until recently, actually! About a dozen years or so.