Theory LONG: Audi Warranty issues, AoA was: Car fax

Phil Payne quattro at
Wed Jan 14 07:59:47 EST 2004

> Steve, good point regarding cooling down the turbo. I generally sit in my
> driveway for about 45 seconds to a minute (depending on the amount of time
> I have driven the car) and at least wait for the turbo to spool down (I
> can hear it doing that if I have been driving for a while and/or driving
> hard) - then wait a bit longer.

EXACTLY the wrong thing to do.

Despite all the crap about oil-cooled turbos and water-cooled turbos, all Audi turbos are
actually air-cooled.  Oil has almost no cooling effect, and serious water flow through the
later models' water jackets (only around the bearing) doesn't start until some time after the
ignition has been switched off.

You need airflow to cool the turbo, and there is no airflow if the car is stationary - except
the paltry contribution of the alternator fan.

The correct procedure is to drive the last mile or so at the very least without using WoT - a
steady tootle along is preferable.  When you come to a halt, switch the engine off immediately
or it will start to heat up again.

And if you mess around with bits and pieces like dump valves, make sure they don't impede the
airflow to the turbo and exhaust manifold.

  Phil Payne
  +44 7785 302 803

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