Hi guys and gals.

I have an S202.082, which is a w202 wagon with M111.944 192ps 2 liter kompressor (supercharged) engine. The car has 480,000 km.

I got it cheap in september 2015 with about 477k km. It had been used mainly on highway journeys.

Engine was OK, MAF was shot and oily. I had all fluids and filters changed and other service like brake pads etc. I also converted it to run on LPG.

I also disconnected the breather hose and let it vent in the air. I also disconnected and blocked the small vacuum tube connecting the s/c plenuum with the oil separator (based on what this guy did http://www.benzworld.org/forums/r170...y-factory.html). Strange enough, I could see some times vapor coming out of the oil separator but no oil whatsoever. There is no visible blow by from the oil dip stick or when opening oil fill cap with engine running (only some oil splattering around).

Currently only MAF is the main issue which has led the ECU to deactivate the s/c.

During city and short (20 km) highway driving the car doesn't use any oil at all. I did a longish 400 km round trip (2/3 highway) and had to add 2 liters of oil (1 liter mid way and 1 liter at the end) as the oil light kept going on and off. Now the stick is showing 1mm below max and hasn't moved from there in the last 150km of city driving.

I talked to my mechanic and he told me most probably it is the valve seals. I read a bit about the valve seals and people are saying that the most obvious thing when valve seals go bad is a plume of smoke on start up after a long rest. I haven't seen any smoke on start up or while running.

Any idea what to look for?

__________________
1992 Mercedes 190D 2.5 turbo 5sp manual. EGT+boost gauges. Boost controller set to ~14.5 psi. 1 1/4 turns on full load adjustment. LPG injection. Next in the list is water injection.

Valve seals will leave a smoke trail when accelerating from a stop. You may need someone to follow you.

Tow things I'd vote for:

Stuck oil control rings. At low engine speeds, oil splash from the crankshaft is low and the rings can control the oil. At high speeds there is more splash and the oil rings can't scrape the oil off.

A clogged crankcase ventilation system. This can push oil into the intake.

Thanks for the reply:

Valve seals will leave a smoke trail when accelerating from a stop. You may need someone to follow you. I have been keeping an eye on the rearview mirror when I accelerate from traffic lights but nothing visible. I will ask someone to follow me.

Stuck oil control rings. Can you please explain what is this. English is not my first language. EDITED: That would be a bummer. Would smoke be visible by someone following me down the highway?. If it was the rings (I hope not) I would have been burning oil anytime I'd be on the highway.


A clogged crankcase ventilation system. I though about this. Do you think I can give it a try to unplug completely the oil separator tube or are you talking about the low/mid load breather by the intake manifold? EDITED: On a second though, the clogged crankcase vent system is more plausible as I had no oil consumption on short 20 km highway driving. Only on longer drives I started consuming oil (enough for the pressure to increase). On the other side though, as I said, I am venting the oil separator in the engine bay and there is no oil visible the, unless it is supper efficient and it goes back the the oil pan

__________________
1992 Mercedes 190D 2.5 turbo 5sp manual. EGT+boost gauges. Boost controller set to ~14.5 psi. 1 1/4 turns on full load adjustment. LPG injection. Next in the list is water injection.

Interesting thread. My buddy had a similar issue that he was able to correct. I will have to ask him what his issue was and what he did to fix it.

Did you find someone to follow you? I would do that as soon as possible.

I had same issue. You need to replace the air oil separator. The diaphragm has likely torn (failed).

Maybe tonight as I have been busy during the day.

__________________
1992 Mercedes 190D 2.5 turbo 5sp manual. EGT+boost gauges. Boost controller set to ~14.5 psi. 1 1/4 turns on full load adjustment. LPG injection. Next in the list is water injection.

I bypassed completely the oil separator (there is no diaphragm as far as I have searched) and there is no blowby or oil leaking from it at all. Mind you have been driving only around today.

__________________
1992 Mercedes 190D 2.5 turbo 5sp manual. EGT+boost gauges. Boost controller set to ~14.5 psi. 1 1/4 turns on full load adjustment. LPG injection. Next in the list is water injection.

I had someone follow me on a stretch of highway, reved it up to 6k rpm in 2nd and no smoke.

Also no oil coming out of the crankcase vent system. I tried feeling by hand the crankcase vent system and on idle you can feel the air coming out in pulses but when revving in neutral it feels as if no air coming out anymore.

__________________
1992 Mercedes 190D 2.5 turbo 5sp manual. EGT+boost gauges. Boost controller set to ~14.5 psi. 1 1/4 turns on full load adjustment. LPG injection. Next in the list is water injection.

Any idea guys? I don't want to start replacing and/or doing job without identifying the cause.

Should I be seeing blowby from the crankcase vent tube? I mean it is an enging with 480k km (300k miles).

Can the valve seals be changed without removing the head?

Thanks

Deni

__________________
1992 Mercedes 190D 2.5 turbo 5sp manual. EGT+boost gauges. Boost controller set to ~14.5 psi. 1 1/4 turns on full load adjustment. LPG injection. Next in the list is water injection.

Now I'm wondering if the baffle inside the valve cover needs cleaning,and or drains in head.
I had to take mine apart on my om617.951 Is boost entering engine?Some motors have a valve part of emmisions.

__________________
1999 w140, quit voting to old, and to old to fight, a god damned veteran

Valve seals only exist to keep excessive oil from running down the guides. When they fail you will get smoke after accelerating from a stop if the engine was idling for a while.

You will get some blow by even with a pretty fresh engine.

With the breather box you have I'm not sure how that system works. There is a message board on the net for the SLK , I'd take a run at posting there. Please post the results here if you find a solution.