Letting the Turbo Cool Down Before Shutting the Car Off

[smart-*ss]

Wow - I've got a G&K 2005 450, came across this discussion purely by accident and really glad I did! First I've heard of this. I will start to give my car a minute or two and watch the heat gauge before I shut off the engine.

BTW, what is it that I infrequently hear running for a few moments after I shut off the engine? I assumed it was a fan cooling the engine (unfortunately I'm not as much of a gearhead as I would like to be )

[sunnyokanagan]

Originally Posted by smart-*ss

Wow - I've got a G&K 2005 450, came across this discussion purely by accident and really glad I did! First I've heard of this. I will start to give my car a minute or two and watch the heat gauge before I shut off the engine.

BTW, what is it that I infrequently hear running for a few moments after I shut off the engine? I assumed it was a fan cooling the engine (unfortunately I'm not as much of a gearhead as I would like to be )

That's your intercooler fan. It's normal after runs at highway speed for this to run on for an interval after you switch off.

But it will be beneficial to run off-boost for the last portion of your trip if you can, and let the engine cool @ idle and the turbo spool down for a minute or two.

[smart-*ss]

Thanks, Sunny! But.....please explain "off-boost" as though I know nothing at all about engines...

[sunnyokanagan]

Light-footed, so the turbo doesn't come in. If you have a turbo, that is.

[atikovi]

I was always told to idle the engine so the turbo spins down from high speeds while still getting oil pressure. Nothing really to do with cooling. If the cooling system is in good condition the engine temperature should be the same whether after a long highway drive or city trip. Sitting there idling in your driveway may make you feel better psychologically, but unless you just had the turbo at full boost, it shouldn't make too much difference in the life of the turbo.

My '05 cdi with 145,000 km was previously used by a courier company and you can bet the drivers never sat around idling before shutting off the engine, and car still has the original turbo.

[smart-*ss]

now I understand

thanks again, Sunny!

[jetfuel]

Originally Posted by atikovi

I was always told to idle the engine so the turbo spins down from high speeds while still getting oil pressure. Nothing really to do with cooling. If the cooling system is in good condition the engine temperature should be the same whether after a long highway drive or city trip. Sitting there idling in your driveway may make you feel better psychologically, but unless you just had the turbo at full boost, it shouldn't make too much difference in the life of the turbo.

My '05 cdi with 145,000 km was previously used by a courier company and you can bet the drivers never sat around idling before shutting off the engine, and car still has the original turbo
.

...you're not serious at all about that statement..are you?
...this has NOTHING to do with cooling turbo time...period...
..after a hard run the turbo will be cherry RED...the oil circulating into the bearing cavity to keep them cool will boil if not allowed to cool...the metal..not the engine temperature...allowing the metal/bearing/carbon seal and rotor to cool will prevent premature failure of the seal/rotor assy.


jetfuel...cooling down...

[Brabus007]

Mobil 1 TV Ep 3: Protecting Critical Turbocharger Parts

http://www.youtube.com/watch?v=PXxqDGW374Q&feature=related" target="_blank">http://www.youtube.com/watch?v=PXxqDGW374Q&feature=related

http://www.youtube.com/watch?v=PXxqDGW374Q&feature=related" target="_blank">http://www.youtube.com/watch?v=PXxqDGW374Q&feature=related

[jetfuel]

...thanks secret agent...cool video of a tiny red hot turbo....

jetfuel...

[fastturb]

most people are not running high boost for long periods of time. while the turbo could essentially spin itself to death (and that would be fun for a short period of time) they have the wastegate to limit rpms and you would probably run out of engine rpm if you ran the turbo at high boost for an extended length of time.

the situation as others are stating is more of "timing" issue of when you have had the high boost and thus high temps and then shutting down and stopping the flow of fresher, cooler oil over the bearings. Unless you always like driving with high boost for a few minutes or more RIGHT BEFORE you are turning the car off, you'll probably never have a problem with turbo bearings coking. But if you like telling the family you are home by driving all-out high boost right before pulling in the driveway - be smart and let the car idle for awhile so the turbo can get pumping oil and cool off. if you don't do this, the family will know you are home by seeing the smoke covering the neighborhood.