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Cooling the Turbo...

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Francois

New member
After a fast run with the Turbo the other night, the fans came on after I switched the engine off for about 10/15 minutes & the next morning had a bit of white smoke when I started it. Is this normal for the fans to start after the ignition is off? will it drain the battery? should I get worried about the smoke? Should I let the car idle for a while for the Turbos to cool off before switching off? also is it better to warm up the engine for a few minutes in the garage before driving or start driving gently on a cold engine?

All advise welcome...

Francois
 
My oil cooler fans come on and off when the engine is turned off, its very normal for a 993. 2 years ago I had a problem where my fans were staying on constantly for well over 30 mins.
This was an electrical problem and the sensor was not working, so the fans would stay on regardless and drain my battery.A small puff of white smoke should not be a problem, fairly common with turbo's, just make sure its not too much.
Ive always let the oil drain out of the turbo's before I turn it off, if ive been pushing it that is. With the new VTG ones im not sure, but its shouldent need more than a minute. To be honest with regards to warming it up, you should just drive straight away. I presume you have an oil temp gauge. I dont open mine up over 4000 rpm until its reached the third marker. just dont cane it from cold, thats all.
Obviously im not a 997 turbo owner, so my experience only applies to my 993, but im sure in most aspects there's not that much difference.
 
A turbo when under full load does get quite hot (did have a picture of my Nissan's turbo glowing light orange which is about 800°C) so stopping the engine when this hot would stop the oil flow, the oil then carbonises in the bearings and seals. The carbon 'grit' can then damage the bearings and tends to pack out the seals which then fail leading to oil passing from the bearings into the turbo and giving rise to (lots of) smoke.

Always wise to drive at low boost (rather than idling) for a bit before turning off.
 
Both pretty normal..
I've had both happen, fans kicking in after parking it up, usually for a few minutes.
The white smoke is the normal oil lying in the bores as per the flat 6 setup.

The book says to drive from cold but I think most people would wait until the oil/car is hot before giving it the beans !

Whilst I don't leave the car to run or cool down, I do drive off boost towards my final destination, just enough time to let the excess heat disapate from the Turbos (and brakes)

garyw
 
Yeah, modern Porsche technology may have improved matters, but I've always been told that switching off the oil flow on an engine with glowing turbocharger(s) will fry the turbo bearings..

Jeeze, first learned that lesson, aged about 10 years old, from my dad after he'd just driven his SAAB turbo for miles near its limits, and had to leave the thing ticking over for about 10 minutes upon arrival..

I always try to warm the engine up and cool the engine down. Not always possible (thanks to other road users), but I try.
 
Thanks for all the tips, first time I have a (911/997) Turbo car and was wondering at the best way to cool it off.
 
Had a turbo timer on a GT4, but would still rather cool everything down on the last mile of driving rather than let it tick over. Reduces the engine bay ambient temperatures as well as reducing oil temps.

Quite fun walking away from a running car though, people give you very strange looks :)
 
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