That's interesting, Bushie. Are you sure it applies to a vehicle which is locked-up and has the engine running on 'timer', as well as to a vehicle which had been left running with the keys in the ignition?
And I have to disagree with Drivesafe:
Originally posted by drivesafe
The new engines are a completely different animal to the old ones plus there is also the problem that installing a turbo timer may void you warranty.
Sorry, but what is so fundamentally different between old and "modern new" turbo-diesels is this regard? Surely the problem of the lubricating oil being 'cooked' in an overly hot turbo bearing housing is exactly the same as it even was?
Perhaps turbos with a water-cooled bearing housing might get a bit of natural thermosyphon coolant circulation after shutdown but these, AFAIK, are relatively rare on diesels.
When left to idle for a couple of minutes after gentle driving, the exhaust gas temp of my 300Tdi stabilises at about 200 C. Presumably this is close to the 'true' gas temp at idle. After hard, fast highway driving, the EGT, even after having coasted down and pulled over, is often still well above 300 C. Again presumably, this is because the cool 'idle' exhaust gases are picking up heat from the still very hot manifold and turbo housing. It can take 3 to 4 minutes of idling before they drop back to the 'normal' 200-odd C levels. In these couple of minutes, while the 'cool' idle gasses are cooling the manifold and turbine housing, the lube oil is also removing heat from the bearing housing.
Without a cooldown period, I believe it is inevitable that the bearing, and the oil remaining in it, will be heated to well above the normal running temp of the bearing by the large reservour of residual heat in the turbine housing.
If turbo cooldown is not necessary, why is it you never see a heavy truck/road train engine shutdown immediately after pulling in off the highway??
Ian &
Leo - SIII 109/GMH3.3
Daphne I - '97 Disco 300Tdi Manual
Daphne II - '03 Disco Td5 Auto
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