smoke after idling .... turbo oil leak?
 

After sitting at a stop light for a minute, I get a big poof of smoke upon acceleration. It has done this since I bought the car about 1 month ago. Would this be related to an oil leak in the turbo system?

I definitely feel turbo boost, and the engine feels strong, but I don't like the extraordinary amount of smoke coming out of the tailpipe.

Have recently had fuel lines changed (running b100 now), new fuel filters, new air filter, valve adjustment, new style breather hose. None of these has affected the smoke. Could it be an oil leak into the turbo that upon spinning up at acceleration blows out a puff of light grey smoke?

Since the car is new to you, and you didn't say whether you've previously owned a 617, are you sure this is not just normal diesel smoke?

Do you get the same amount (and color) of smoke under very gentle acceleration as under heavy acceleration? How about when you're at 40 mph or more and floor it so the kickdown switch engages?

To your oil leak question: How much blowby do you have? If you take the top cover off the air cleaner housing (engine off) and look inside, is there visible oil? If so, this can drip into the U-tube and be sprayed into the intake manifold by the turbo. But even then, some on this forum maintain that would contribute to a fouled manifold, but not necessarily smoke.

An oil leak inside the turbo itself (from the front oil seal) seems unlikely, and probably wouldn't be of any significant volume.

When I've seen this scenario is the past, it has usually been valve guide seals.

Is this a major and necessary repair? I haven't had the car long enough to know if there is an oil consumption issue. I see valve guides and a valve stem seal kit at the mercedes shop store on this site, but not valve guide seals.

Mine did this (badly) when I had a tight valve causing a miss at idle. Take a listen to your tail pipe at idle and see if the exhaust pulses sound smooth, or if you hear a chug, chug, chug.

Thanks for your reply :). Yes, this is my first Diesel, and first Mercedes, but the smoke seems to be more than what I've noticed on other 300D's on the road. I started the car up this afternoon and observed the exhaust while the car is sitting still. It emits a steady stream of greyish/white smoke at idle (car is warm to 80C). It is definitely noticeable, but not enough to build into a cloud while idling. It I can follow the trail of smoke about 8-10 feet from the car in a very light breeze and then it dissipates too much to see anymore.

I tested for blowby today also. With the car running, I unscrewed the oil cap cover. A little bit of whitish smoke came out. I put the cover back on, but didn't twist it closed and it slowly kind of vibrated around. Not really enough to make it dance, just a steady vibration that caused it to slowly rotate.

Seemed to pulse smoothly, I didn't hear a whooping or chugging that significantly interrupted the flow of exhaust out the tailpipe. Plus I had a valve adjustment done last week.

Consider this - the smoke you are seeing may not be burning oil. Instead, it may simply be that you have really worn injector nozzles, or the PO may have adjusted the ALDA screw to give the engine too much fuel. I wouldn't be overly concerned - the smoke is all part of the diesel experience :D

Let me ask you this... The exhaust smells very B100 "french fry"-like. Would I be able to smell burning oil if that was the cause of the smoke?

Did it blow a puff of smoke on dinodiesel? If so, what color?

My car has a brand spanking new head from Metric and a new timing chain. I run homemade b100 and have the exact same (seems like) idle smoke--not a whole bunch, but enough to notice if you're looking. Funny, last month I ran out completely of my brew and nobody except a hippy coop around here sells b100, so I filled up with dino 45 cetane, and the dang thing smoked less at idle. More under load, though. When at my Indy's a couple of months ago for state inspection, I asked him to observe the idle smoke, and he says the smoke at idle is definitely fuel smoke. I have a little oil consumption--1.5 quarts per 4k. My next step is to retard the timing to 26deg. I've heard the bio burns slower or something like that, which causes an incomplete burn, especially at low rpm. That could explain why the dino smoked less.

My advice to you would be to slow down a tad on diagnosing a problem and put some miles on the car and monitor oil consumption. Get someone else to drive the car and you follow it in a chase car. Tell the driver to demonstrate a few different situations like WOT, second or third gear redline, then a slow takeoff. Looking at the frequency of problems that cause smoke on this forum, I'd say turbo seals going bad is unlikely.

You would definitely smell burning oil. For comparison's sake, out on the road I would try to find the smokiest gasser and follow it for a while so I could get a feel for what burnt oil really smelled like. With all the other diesel aromas interfering with the exhaust, it's hard to pinpoint the oil smell. But find some redneck Ford Escort that's blowing heavy blue smoke and follow it around for a while. Oil has a bad acrid smell--of course it could have just been the people in the car! Hope noone here owns an Escort in Va!


Good luck!

Thanks for the thoughtful response, GRIESL. I honestly can't comment on the dino diesel exhaust smoke; the first thing that I did after buying the car was fuel up on B100 (after first having fuel lines and filters changed). As tempteratures in Pacific NW cool below 40F, I will start blending 50/50 biodiesel/petrodiesel. Perhaps I will notice a difference in color at that point.

The oil level on dipstick is *just* below the top notch. Oil change performed about 500 miles ago.

check your oil level.



if it's overfill you may (and I don't know if Mercedes has a way around this, but is a common turbo problem) have overfilled above the oil return line from the turbo.


Check your levels. And also check for play in the turbine by wiggling it around (engine OFF!) with you fingers.