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1991 Mercedes 350SDL
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Discussion Starter #1 (Edited)
Hi all, just had a few questions that I was hoping someone might be able to answer. If anyone has had something similar, I'd be happy to hear what the deal was with your car. Sorry if I'm long winded... *questions scattered**

Power steering pump broke off of the motor at the mounts, the metal seemed fine previously, but looking at it now, I suspect it's either been under stress or had a defect in it from manufacture. (casting fracture?)
I found one to replace it with: Mercedes 350SDL Power Steering Pump

**ANyone used this pump? Any good? Thoughts?

** MAIN POINT OF INTEREST**
Also seem to have oil sweating through the gasket around cylinders 1 and 2... not much, just enough to make a mess. The knock noise out of cylinder #1 isn't quite in propper rhythym, so I don't think I'm hearing the piston hit the wall, and it does sound like a few other 350SDL's I've heard. The noise dissappears however, at about 1900 rpm or so.... *Thoughts?*

Never really had any oil consumption during regular running, except for once during agressive highway driving. 145km/h for a prolonged period of time.... (about 90mph) There was never any drivability issue, always smooth, even power and consistent mileage. (about 900km/tank... 20-22(US) mpg -is that propper?)

There is a vibration and engine shudder at idle, sometimes enough to give a bit of chassis shudder, but the mounts were replaced about 3 years back... sadly two of those 3 years its been sitting waiting for work which I am only getting to now... But as rev's increase, even while there is still a knocking noise, th vibration is gone...

**If it was the piston hitting the wall, and ovaling it out, would the noise dissappear as revs increased? What about my lack of oil consumption and the vibration? Do you guys think she's gona die soon?


When the car has been sitting for a long time between engine runs, ie/ a few weeks, it still starts without any real difficulty, regardless of temperature. (I live in canada and it starts in the dead of winter) BUT the exhaust is a bit greyish, the odd time with a blueish tinge... this goes away once the engine is warm. At high rpm operation in park, after about 20-30 seconds regardless of operating temp, the exhaust goes smokey grey.

** Is this normal? I've owned no other diesel, ever, so I don't have a point of reference. My gasoline cars never did this... except for an '88 Olds that I nicknamed "Uncle Buck"

The turbo and the EGR were redone by the previous owner, but I don't have receipts nor can I find out who replaced them. The local MB dealers don't have records on this car either. I do know, from the previous owners wife, that the car was routinely serviced and babied for the most part. I don't know if it ever suffered bent rod syndrome, and am curious to get its "data card" can anone run my VIN?


Any thoughts? Help me please :)
 

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1991 Mercedes 350SDL
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3 Posts
Discussion Starter #3
You may have a faulty injector. it almost sounds like a rod knock but it's the injector nossle sticking. clean or replace that injector and see what it does then.
Would these injectors be ok do you think? Your Parts Search Returned 1 Part(s)

At the same time, I would have to replace the injector heat shield I guess, right? And would I need to do all the injectors at once? Or just the one that seems to make noise?
 

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The 350 diesel motors had problems with the connecting rods stretching due to faulty heat treat is the information I have. Not sure what year(s) were involved. This could be a potential source of the knock.
 
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