How much truth is there to this turbos cool down thing

[jbtexas]

I have read through some old posts with differing opinions about this. How many of you wait a few minutes after driving (at idle) to cool down the turbos?

thanks

[Bigglezworth]

I have read through some old posts with differing opinions about this. How many of you wait a few minutes after driving (at idle) to cool down the turbos?

thanks

All depends on the driving methods prior. Running full tilt on the track - for certain. And I do it even after a cool down lap. Driving home in rush hour traffic - never. High RPM for the turbo equates to increased heat. If you perform a full boost run coming up the street to your house, then you would run it for a half minute to dissipate some of that new energy. I highly doubt you do this so generally speaking most people would find they can simply turn off ignition when they arrive at their final destination.

[snoopra]

I think the manual or some Audi material recommends allowing the turbos to come to a complete stop prior to engine shutdown. So idling 30 sec to a minute should do. Shutting down after full throttle could cause turbo failure if they're still spinning when the oil flow stops.

[DuckWingDuck]

ya, exactly@tim. it all depends on what you were doing right before.

[cornishmoocher]

I just generally drive for a few minutes off boost before shut down, that will do the same thing.

[KfabR8]

allowing the turbos to come to a complete stop prior to engine shutdown.

If your turbos come to a stop when you get off the throttle, the bearings are shot!

The turbine should start turning the second the exhaust flow starts and should not stop until the exhaust gas stops flowing. They're exceptionally easy to rotate.

[jbtexas]

Good feedback. Of course I never come roaring home at full throttle... but I do sometimes pull into a shopping center, parking lot, whatever, after spirited driving. I probably need to just keep doing what I am doing...which is giving the car about 60 seconds before shut down...every single time to be safe. Thanks all

[KfabR8]

Doesn't the car have an after shut down pump that circulates oil through the turbo's bearings until they get to a certain temp? Seems I was told this or read this long ago. You can hear some sort of electrical motor working after you shut the car down if you listen carefully and the (cooling) fan's not running.

[Hy Octane]

I usually wait until the electric fans stop before I switch her off... and yes, there is an after-run turbo cooling recirc pump that runs on for a few mins after shutdown.

[snoopra]

The after-run pump only circulates water, not oil.

[LIRS6]

Important to the life of your turbos is to avoid bringing on boost until the oil has warmed up - say to about 175-200 degh f.

[Al Pettee]

All depends on the driving methods prior. Running full tilt on the track - for certain. And I do it even after a cool down lap. Driving home in rush hour traffic - never. High RPM for the turbo equates to increased heat. If you perform a full boost run coming up the street to your house, then you would run it for a half minute to dissipate some of that new energy. I highly doubt you do this so generally speaking most people would find they can simply turn off ignition when they arrive at their final destination.

Exactly.

Since I don't (usually ) drive up my driveway at peak boost, the turbo's have been quiet for a minute before I come to a stop, so then it's not much of an issue (with my Porsche 993 and 996 typ 911TT's). My Audi though is currently just a NA RS4 ( ), although just about set for an MTM supercharger conversion next month.

[skiwi]

couple of points:
1) the afterrun pump is designed to circulate coolant thorough the turbo housing every time the car is turned off. this is designed to avoid heat soak

2) the oil in the turbo bearings is really only any use when then the turbo is spinning in those bearings. when you turn off so does the turbo. heat soak can cook the oil and coat the bearing surfaces with residue causing additonal stress and eventual failure. hence the afterrun pump.

i only ever allow cool down after a hard run, never around town or for normal motorway runs.

[jonas21]

i always let the turbos cool down after going hard. the best thing is to drive a few minutes at normal speed after you have used full throttle. this is alot better than letting it idle at stand since the engine will have much more (and thus better) airflow while driving at normal speeds. this is the safest way to make sure that your turbos will last long.

[DuckWingDuck]

ya, when you're moving, there will be more cool airflow, when your car is idling in the garage, it's just sucking in the hot air that it's venting.

[Mr Balsen]

i always let the turbos cool down after going hard. the best thing is to drive a few minutes at normal speed after you have used full throttle. this is alot better than letting it idle at stand since the engine will have much more (and thus better) airflow while driving at normal speeds. this is the safest way to make sure that your turbos will last long.

Agreed 10000 %

Frederic

[skiwi]

it's probably worth asking how many have had a turbo failure? modern oils and water circulation seem to have taken premature turbo failure away....

[jonas21]

i had a failure with the old C5 RS6 at 110k km...had to get both replaced.