Ian964

I have read a lot that you should let the car run 2-3 minutes after you drive to let the oil keep pumping to the turbo so that they don't go bad.

Well I let my car stay running today and the engine actualy got hotter while I let it sit there and run.

I know this because my heater/blower started up while I was letting it idle. (The bearing is blown in this and it makes an AWFUL noise)

Is that normal?

Adrian

Dear Ian,
The fan starting up is because the tmep sensor in the pipes has detected an over temp situation and it is dumping the hot air overboard. The blowers use the engine driven fan air so yes you are hot. I have sat at idle in a turbo for a lot longer than 2 to 3 minutes and not gone into overheat mode on the fans. You do need to allow the turbo to settle at idle before shutting down.
Ciao,
Adrian
911C4

L8Apex

If you do not run the car hard (no boost for 2 minutes)before you come home after a drive and then shut it off you will be ok. The primary reason for doing this is to let the turbo wine-down before you shut down the engine (engine off= no oil pumping to the turbo). Belive it or not the turbo is still pulling 3-4k rpms when you shut the engine down. If you are lazy buy a turbo timer that will save ya time.

Geoffrey

Actually, the real reason to idle down is to allow the exhaust gas (which is much cooler at idle) to cool the turbo. Not running the car hard before you come home does help, but you really need to let the turbo cool before shutting it off. If you don't, when you will cause damage to the turbo.

ZAMIRZ

Just don't let the boost pass 0 psi for the last 2-3 minutes of your drive and shift early and you'll be fine. Turbo timing is a good way to do it if you want to boost up your driveway.

Kevin

Folks;

On one of my desks at work I have started a 930 Turbine wheel collection. Many are from fellow Rennlisters, I have 3 of my own in the heap. The jist of it is, heat, heat, heat. The turbine housing is full of BTu's and soaks through your turbine wheel. When the engine is shut off oil supply stops flowing through the bearing housing. Oil not only adds lubrication but it provides cooling. If you do not let your car idle for a minimum of 2 minutes you are killing your turbo, plain and simple. If you can't do 2 minutes give yourself one.

I have a catch phrase. Question "What do you do when you pull up to the gas station for a fill?" Most people will pull to the pumps and shut the car off. Usually we are in a hurry and can't get tot the station any quicker! Pull in and pull over, stage your car for a minute or two then proceed to the pumps. As Geoffrey mentioned the idle fuel mixture will cool the turbine housing down at idle. It WON'T cool your turbine housing down in drive mode.

Jump over to the 996TT forum and look at the video of the car on the dyno. Most of us have seen our turbine housings glowing white, some of us have been lucky to see the rotational movement of the turbine wheel. Heat kills and we do not have water cooling for our engines, nor watercooled bearing housings!

Sameer

Which turbo timer is the easiest and best looking to hook up?

oscar965

I read on the 930 forum (search for turbo timer) that letting the car idle for 2 or 3 minutes will cause other problems on the engine on the long run. Look here: <a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic;f=2;t=000386#000002" target="_blank">http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic;f=2;t=000386#000002</a>

It's a bit confusing. What does Porsche sa about this ?

Kevin

Oscar;

Two minutes of idle down time will not lead to significant problems. Heat soak will set in if your car just sits and idles at prolonged times. For the majority of people, letting the car idle for at least 1 minute is going to be a stretch.

Autobahn

Oscar,

I would also like to know what Porsche says. I drive a 993tt and nothing is mentioned in the owner's manual about having to idle the car for several minutes before turning off the engine.

Kevin

Cobra06 posted this on the 996TT forum:
Page 61 of the owners manual:
Paraphrased but, the manual states a 2 minute cool down

STOPPING ENGINE
Do not turn off the engine after hard or extended driving. Allow it to idle for 2 minutes before shutting down.
--------------------------------------------------------------------------------

Autobahn

Hi Kevin,

I have checked the 996tt manual (german version) and I couldn't find anything in it either??!!!
Could there be a difference between US and ROW?
Has anybody else checked their manuals?

Patrick

Geoffrey

See my post on the 930 forum with some pictures of a 500mile turbo that has had 1 hot shutdown.