Lord_Galva

After doing an oil change today I noticed a new sound coming from the motor.
It only occurs when the motor is shut off.
Every other "shut down" I will hear a high pitch whine.
It's not consistent and it's not that loud. Definitely not the belts or the fan.
I worry that it's the water pump.
I plan on posting what the sound, sounds like later today.

odurandina

ummm have ya been to the Sci-Fi Channel?

FRporscheman

It's your turbo spooling down, yo. You need a turbo timer!


Maybe you can ask someone to shut down the car while you lean over the engine bay and try to find out where the sound is coming from. I've never heard of such an issue, but maybe it's a relay buzzing, or air bubbles fizzling around, or some kind of weird alternator feedback in the speakers, just shooting in the dark here.

I don't see how the waterpump could possibly make noise after the engine has been shut off.

968norway

Could be a vacuum leak. There are some bits by the firewall, a one-way valve, this can make whining noises. My car tends to hiss a bit after shut down, haven't had any problems though.

FRporscheman

968norway, you make a good point. I've heard on the 928s, the vacuum check valve by the brake booster can make a high pitched whine when it starts failing. Maybe the same thing can happen on a 968.

Lord_Galva

I forgot this thread was up.
It was the flange washer on the end of the lower balance shaft.
There is a little tab on the washer that lines up the "O" mark on the BS.
That tab broke and what was making the noise.
Took about 3 hours to reinstall the balance belt, but it was nice seeing that my timing belt hadn't lost any tension since installing last month.

PS if there is anyone in Nor-Cal thinking of rebuilding their top end I know a great machineshop and I can volunteer some hands on help.
The restored hp and you can get is awesome.

FRporscheman

+1, a valve job and correct valve timing makes a very big difference.