I have a W124 1992 Mercedes 300D 2.5 Turbo with 240K miles. It has some smoke problem that I wonder if anyone can help me? I searched the forum but did not find any post matching my exact symptom.

When I start up the car, it often (not always) gave out a puff of white smoke (not vapor. Smell a kind of burnt). When driving for the first few miles, there is no smoke if RPM is below 1500. But once engine go over 1500 RPM, I can see white smoke. This will keep going for a few miles, then it got cleared up and no more smoke.

I heard white smoke is unburnt diesel, and it usually happens when engine is cold, or during hard acceleration. However in my case, the white smoke will occur as long as the car has been parked for some time, regardless if the engine remains warm. I still need to drive a few miles to get rid of the white smoke.

I have tried two types of diesel additive (Run-rite and Diesel Kleen), and that did not seems to help. The car runs fine otherwise. I just took the car for a 2500 miles trip from California to Nevada to Arizona and back, and it runs like a champ. The only thing I noticed during the trip is when going uphill at 65 mph, the termperature rises to 110 F. But on flat ground at 75 mph, the engine temperature is between 80 and 90 F.

I really appreciate any comments/suggestions.

Thanks.[/align]

 

Hi

Itsounds like it time for a valve adjustment.

 

srry double post [:@].

 

Maybe some can straighten me out but white smoke is usually burning oil. White smokecan also be coolantbeing heated in the cylinder. If it's coolant , the white smoke is wet like fog.Sources of burning oil are piston wiper rings, cracked headgasketandworn valve stem seals & worn valve guides.Coolant is the gasket or the head.

If it's a piston wiper the smoke isworse when the engine is hot. Also,oil consumption is high and youknow it's not from leaks. If it's during start upand is moderate during normal ops. it's usually the guides/seals. Pulling the intake and inspecting the deposits on the intake and exhaust valves will confirm if seals are leaking.With a lighted fiber optic bore scope you don't need to remove the intakeand this saves mechanics time.

My guess is the valve stems are worn, allowing oil to be pulledaround theintake valveseals/guideson the intake stroke and into the cylinderbased on your claim of 240Kmileage. Any thoughts?

 

My Car dose puffs white smoke during hard acceralation but no smoke @ idle should I be concern about it???????

THX