'82 300SD Burning Oil - PeachParts Mercedes-Benz Forum

nickh1234 · #1 10-28-2011, 08:18 PM

My car has recently been smoking so bad that it is embarrassing to drive. When idling, a thick white cloud of smoke builds up behind me and engulfs the entire street. The smoke is white and smells like burning oil. When cold the car doesn't smoke at all. It is only when warm or under hard acceleration that it smokes. The compression is not consistent but all cylinders are above 300 psi. I replaced the turbo thinking that the oil seals were bad but that did not fix the problem. The outlet of the turbo is covered in oil while the exhaust manifold is dry. Is it possible that something with my oiling system is blowing out turbo seals? My oil level goes down noticeably every time i drive so I am sure it is burning oil. What else could be causing the smoke?

This is what it looks like when idling warm:

300SD Burning Oil - YouTube

kerry · #2 10-28-2011, 08:31 PM

That's a lot of smoke. You don't have the vacuum pump which vents into the intake do you? Did you replace the turbo with a new or rebuilt one? You could pull the turbo, start it up and see if it still smokes. Did you try that when you replaced the turbo? Have you pulled the PCV hose off to see if it makes a difference?

rscurtis · #3 10-28-2011, 08:48 PM

I would vote for something besides the mechanical aspects of the engine. It sounds too good to have a bad piston, broken rings, etc.

kerry · #4 10-28-2011, 09:00 PM

X2. It looks like my MG Midget when it was sucking oil directly from the PCV system into the intake. Small amounts of oil burn blue, huge amounts of oil burn kind of white.

nickh1234 · #5 10-28-2011, 09:15 PM

Forgot to mention, I replaced the stock intake and the pcv vents to the ground. The vacuum pump I believe vents internally to the engine. The replacement turbo was off of a spare engine I had from a low mileage car. I have the engine rigged right now to run without the turbo and it does not smoke. The problem is that it is way too loud to drive it around to get up to temp. The intake manifold and turbo compressor outlet is covered inside with oil however the exhaust manifold is dry inside.

kerry · #6 10-28-2011, 09:27 PM

Quote:

Originally Posted by nickh1234

Forgot to mention, I replaced the stock intake and the pcv vents to the ground. The vacuum pump I believe vents internally to the engine. The replacement turbo was off of a spare engine I had from a low mileage car. I have the engine rigged right now to run without the turbo and it does not smoke. The problem is that it is way too loud to drive it around to get up to temp. The intake manifold and turbo compressor outlet is covered inside with oil however the exhaust manifold is dry inside.

You've got your answer then. It's sucking oil thru the turbo.

nickh1234 · #7 10-28-2011, 11:39 PM

So is it just a coincidence that the second turbo had the exact same issue? I don't want to try another turbo just to ruin it also. What would cause premature oil seal failure? I've never had egts higher than 1200.

kerry · #8 10-29-2011, 09:15 AM

I suppose it's possible that you have very high oil pressure in the feed line to the turbo and it's blowing out the seals. Never heard of it though. If the turbo inlet is not covered in oil, it can't be coming thru the PVC system.

SD Blue · #9 10-29-2011, 10:49 AM

Could it be a problem with the turbo drain? If it isn't draining back to the pan, you could have pressure build up that way. I haven't read of this happening, here on the forum, but still the possibility exists.

Just a thought.

vstech · #10 10-29-2011, 11:42 AM

I have heard of the Crank vent check valve getting clogged up and needing repair, perhaps the turbo drain is clogged? 90psi could easily blow out a seal I'd think...

nickh1234 · #11 10-31-2011, 01:08 AM

My turbo drain is definitely not clogged. If my pcv system was not properly venting the crankcase, could this create enough pressure on the turbo drain to not allow the oil to drain back into the pan and create enough pressure to blow out the turbo seals?

vstech · #12 10-31-2011, 06:23 AM

maybe, but I'd think EVERY other seal on the motor would blow out first... or at least show signs of blowing out, and leak badly.

pawoSD · #13 10-31-2011, 06:56 AM

Does the smoke smell like oil burning? or like unburned diesel. If it smells like diesel it could be a failed pre-chamber ball allowing diesel to just dump in there and not burn correctly.

oldsinner111 · #14 10-31-2011, 07:00 AM

pull a few glow plugs and check for oil,the valves seals fail from age not miles

kerry · #15 10-31-2011, 09:02 AM

I don't think bad valve seals would cause the massive amount of smoke he's seeing. That engine is ingesting a great amount of burnable fluid far in excess of normal to produce that smoke.