My 300SDL has started smoking and consuming lots of oil. The smoke smells like burning engine oil and is gray/blue. No blowby is detected if I remove the filler cap while the engine is running. The interior of the compressor side of the turbo is oily and has a small puddle in the intake. The turbine side is sooty, not oily.

I suspect a failed turbo oil seal on the compressor side. What do you think?

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Never a dull moment at Berry Hill Farm.

I'd suspect the same.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I don't think you have enough evidence to conclusively decide that the turbo oil seal has gone bad, although that is the likely conclusion. You could still have some kind of higher-rev blowby situation or something like a worn or unsealed valve stem.

You may be able to isolate the problem further by pulling off the intake crossover tube and running the engine a bit that way. If you are getting oil blowing up from the turbo I'd say you have it traced.

Also, I think the blowby is vented to a location just downwind of the EGR valve (can't remember exactly). You could always make a few test runs with the blowby tube connected to some longer piece of tubing hanging down the side of the engine. It would blow out that tube onto the ground instead of burning.

I'd hate to see you tear into the turbo and then find it was some other cause.

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

I agree.

These can suffer a head gasket failure that dumps oil from the timing chain cavity into #1.

The characteristic failure of the turbo is very low oil smoke at idle. The airflow is not sufficient to carry the oil up to the crossover tube..........so, it's pooling in the riser tube. When you mash the pedal, this pooled oil flies into the crossover tube and down to the cylinders resulting in massive smoke upon initial acceleration.........gradually decreasing to a modest amount of smoke after the initial wallop.

Thanks all for the input.

The crossover tube interior is pretty oily.
That's almost exactly the smoke scenario we're encountering...modest smoke being a visible trail at any speed. Consuming a lot of oil too...2-3 qts in 90 miles.

Can't run it w/o crossover tube...I pulled the turbo this afternoon.

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Never a dull moment at Berry Hill Farm.

BTDT. Usually, it tells you that it's down 3 when the oil pressure gauge starts falling off the peg........

Actually, you can start it without the tube and observe the oil pooling at the output of the turbo.........it starts to gurgle down there.

Would the leaking head gasket cause a similar issue of "loading up" at idle then blasting all that smoke out upon acceleration?

My SDL does this BIG TIME and I'm not entirely convinced my turbo is toast (although I'm pretty sure) as there are many quirks the 603 exhibits that could be my issue. It runs fantastic aside from the huge smoke show

One concern is that my oil consumption is not huge like others exhibit, maybe two quarts over 5000 miles. So I'm at turbocharger, headgasket, or valve guides/seals... I resealed my IP already and the oil cooler does not leak.

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

We'll know more in a few days...the SDL's turbo rides to Waco today for a makeover at Majestic. It should be done by the time I get back from AZ; I'll stab it back on sometime next week.

I'll post the results then.

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Never a dull moment at Berry Hill Farm.

I never had a head gasket failure on the 603.........to my knowledge.........so, I can't comment personally. But, I would not think that the head gasket failure would have similar symptoms as the turbo. The oil leak to #1 would be gradually increasing as crankcase pressures rise.........so, you'd get moderate smoke at idle and increasing smoke with rpm's. The increased smoke with rpm's might not be noticeable if it dissipates with airflow behind the vehicle.

The '86 consumes about 2 1/2 quarts in 5000 miles. I'm convinced it's the turbo and one of these days I'll get my lazy ass out there and pull the damn thing.

Did you do a compression or leak down test?

Nope. My diagnosis, while wrong, led me to think the turbo seals had failed. Thus, no reason for a compression or leakdown test.

I think my next steps will be:
1) pull crossover and confirm integrity of turbo repair
2) if turbo is OK, I'll pull the turbo and exhaust manifold to inspect the exhaust ports for excessive oil.
3) 1f #1 comes up wet that pretty much points to a failed head gasket.

I'll reassess what I need to do at that point...I don't have a lot of spare time to mess with cars these days and may just sell it for parts or patch it up and flip it.

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Never a dull moment at Berry Hill Farm.