MB newbie needs help--am I buying a slug?? - PeachParts Mercedes-Benz Forum

Jack01 · #1 06-12-2008, 05:37 PM

Hello,

I am considering purchasing a 1992 2.5 Liter Turbo Diesel (E-Class) with an automatic transmission here in Europe. The car has done about 142,000 miles, it is rust free and, according to the current owner, has a new automatic transmission. I took the car for a test drive and have some questions regarding acceleration.

I have never owned a Mercedes before and expected a bit more pep--especially from a turbo. Going up hills, it seems quite sluggish. I put my foot to the floor--I was traveling at about 35mph--and it accelerated, but only very gradually. The motor does not seem to be struggling.

On a level road, the car seems more responsive. I can put my foot to the floor and there is the characteristic pause of an automatic transmission, but then the power comes in quiet smoothly--not like a rocket, but you can feel that it has plenty of power left.

After doing some research on the internet, I am aware that there was a non-turbo version of the car (also with a diesel engine) that had only 90 hp, whereas the turbo diesel I am considering has about 125 hp. Is the sluggish behavior up-hill to be expected of a Mercedes Turbo Diesel? Do the circumstances above suggest any particular problem with the transmission, the engine, or the turbo?

Is there anything I can do that might be a simple fix for this problem? I don’t know anything about turbos--if the turbo is defective or doesn’t work, can the car still run? If the turbo is defective, how expensive is it to correct?

If this problem sounds like something more serious (i.e., the engine)--is it possible to do a compression check on a diesel motor?

Many Thanks,

Jack

cphilip · #2 06-12-2008, 05:41 PM

Let me ask you this.... Have you ever driven ANY brand of Diesel car? This is important.

A Diesel motor is particularly a bit more suggish, turbo or not, than a Gas counterpart. So it might just be your not having anything to compare it to. Sounds to me like it would be nice for you to get a drive in a like car with like engine and then compare to this one. OR have someone do an inspection for you that has driven a like car. Its got nothing to do with a "Mercedes Diesel" so much as it has to do with any kind of Diesel.

Jack01 · #3 06-12-2008, 06:08 PM

Actually, yes, I have driven a Peugeot diesel and a BMW 3-series diesel, both of which were non-turbos. They both seemed peppier. On this Mercedes, I literally had to keep my foot to the floor going 40 mph up a hill.

cphilip · #4 06-12-2008, 06:24 PM

Does sound like something is wrong to me Jack. Should be doing better than that. For one thing, if you had it all the way to the floor it should have kicked down a gear and accelerated at the very least. For that matter it could be a simple kick down switch or even a throttle linkage problem.

I expect you should have it inspected then if your serious about the car. Maybe its something simple that you can use to bargain down the price.

RUN-EM · #5 06-12-2008, 09:30 PM

Replaced tranny. Kick down is mal-adjusted probably. Should haved kicked down a gear and accelerated. At very low revs, diesels do not have any gumph. Then there is the turbo spool up. Can't spool up if less than 2000 rpm.

Regards

Run-Em

Brian Carlton · #6 06-12-2008, 10:24 PM

Take the vehicle and accelerate from 0-60 mph on a level road. Use a stopwatch and get an accurate time.

Report back with results.

It's all wild conjecture as to whether the vehicle is performing properly. Your anecdotal story of climbing a hill is meaningless.

babymog · #7 06-12-2008, 11:17 PM

The most likely problem is the overboost protection circuit not allowing boost enrichment. Search for "switchover valve" or "overboost protection" here. Could also be a bad turbo, or a bad wastegate control (fairly common on the US '92/'93 E250D). And there is the possibility of restricted fuel flow (filter) or air flow (filter) or exhaust.

Should be fairly peppy, around 10seconds 0-100kph.