Looked at the '92 300 SD that is for sale locally. God bless that Starmark warrany! These folks have owned it for a little over a year and had both the engine and AC evaporator replaced no-charge. The car is immaculate, especially under the hood with the brand new engine gleaming in there. The car has never been touched by snow so we didn't violate it with a test drive yesterday (SE PA).

However, they are asking substantially over book for the car and I probably couldn't be sincerely interested in it unless it could be had for somewhat under book. So here's my technical, if somewhat academic at this point, question. Is the new engine any different than the original engine that had the problems? What exactly made the diesels in these cars perform so poorly when Mercedes has such a good reputation otherwise for their diesel engines? Or is my impression of their reputation in error? Also, was there a flaw with the evaporators that has been remedied or can that horrendous bill be expected to be seen again?

The evaporator problem seems to be solved. It was a biological problem...it seems that there are little bacteria that eat alluminum... They now dip the new cores.

The engine has been upgraded in the area of the cylinder head. I have seen them go over 300k miles, but some not make 60k. I think it is in the service.

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Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS

I'm a little confused. I thought that the 140-series diesel used the 350 engine? If so, the problem I heard about was that the old 300 engine was bored out to accomodate bigger pistons, and that was the problem -- LOTS of trouble with cylinders becoming out of round, bent connecting rods, etc. People I've talked with say to run, as fast as you can, in the other direction rather than buy a 350 . . .

RE: the dreaded evaporator problem, having replaced mine on my '93 400E this summer, my tech said MB has gone back to COPPER, rather than aluminum, evaporators, due to the corrosion problem. He used an aftermarket copper one in my car.

Yes, W140 uses 3.5L Desiel, and YES, the engine has alot of problems. I would go for 3.2L I6 instead. Though there are gasket problems, it's pretty much bulletproof.

Andy Kuo

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1992 Mercedes-Benz 400SE
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2002 Acura TL Type S
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Thanks Steve,

That's exactly the nuts and bolts information I was looking for. When something performs as poorly as these engines often seem to, there is generally a clear engineering defect that is at the root of the problem. MB isn't the first manufacturer to get in trouble by modifying an existing powerplant to get more displacement from it. It's a shame that they aren't replacing these with something redesigned from the ground up to eliminate the problem. I wouldn't want to be trying to sell one of these cars or paying out of pocket to replace the engine again so I guess I will stay clear of it unless it's practically a "free to good home" situation.

Regarding the evaporators, copper sure sounds like the way to go. I doubt MB saved much by switching to aluminum on that part given the number of them that were probably replaced under warranty.