Turbo cool down

I remember reading years ago of the importance to allow time for turbo units (both gasoline and diesel) to cool down from operating tempertatures because of the 'heat soak' effect. In an '86 300SDL, does this hold any more or less true? Has Merecedes made some special provisions most people are unaware of that will protect the turbo from oil coking in the bearing? I have heard that some manufactures employ some sort of oil siphon that continues to circulate oil through the turbo bearing after the engine has been shut down.

On a recent cross country trip, the approach I took on this issue was to allow the engine to idle during all quick stops without shutting it down (refuelling and rest stop breaks) and when shutdown was necessary for longer stops (overnight stays and restaurant visits) the engine was allowed to idle for at least five minutes prior to shut down. Is this an approach I should continue? Any modifications to these practices? Is oil dilution at idle as much an issue with diesels as with gasoline engines? I really don't relish the thought of turbo replacement and since the car has about 155K miles, I would like to think that, in Mercedes terms, I'm only half way there. Thanks for your input.

Whoever answers, please comment on the new ones as well. I'll look for something in the owner's manual when I get it, but the car hasn't been delivered yet.

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Rick Miley
Tampa, FL
86 190E
87 300E

I don't know any of my customers that take the care to allow the car to run for a while before turning off the engine and I don't see any turbos burning up! I think that they just don't need to be reved up then shut down abruptly with the turbo under full turn in RPM's. I hope this helps. The best thing you can do for your turbo is keep the oil changed!!

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

I am unaware of any new designs that suggest otherwise. But I do know that on older turbos (this applies to all cars, just especially turbos) it is extremely important to allow the car to idle before shutdown. For the reason if you shut the car right off the turbo is starved of oil and will cause premature failure. I have seen lots of Porsche turbos fail because of this. I have also seen Mercedes and Audi turbos fail too, due to oil starvation. The owner's manual does recommend a cool down for turbos, and all cars after hard driving. It is something I always do and highly recommend others do, it is a very small preventive maintenance step to avoid major repair bills.

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Adrian Eckenrod
MBCA, PCA, BMWCCA & SCCA* member
86 190 2.3-16
83 944 ITS Racer