With my recent hesitation of the engine, I used seafoam and replaced the spark plugs. The hesitation is gone, but when I turn the engine off I get a 1 second whining/screeching noise coming from the engine bay. Sounds like a high A coming from an oboe or a flute.

This only happens when the engine is warmed up. If I turn the car on in the morning and turn it off after a few seconds the sound is not there. But if I do the same thing to a warm/hot engine the noise is there.

Any ideas as to what is causing this noise?

 

Hahahahaha a flute

Ok. I think I know what you are talking about. You forgot to use gasket maker!!!! Yes gasket maker!! Let me explain. Everytime you change your spark plugs (im assumings your car is an SC3) you must remove the intake, then the piping, then the throttle body. Well, when removing the throttle body you notice that there is some kinda dark brownish residue around the original metal gasket. That is a the sealant used to seal off the area around the original gasket. You must have forgotten to reapply some to that area so that whinning flute noise is a leak my friend. Just simply run to your nearest autopart store and ask for some gasket maker and reapply it to that area between the throttle body and the intake manifold.



So remember..the flutey whiny noise is a leak. Nothing major but needs to be taken care of.

 

Thanks for the heads up Jspec. I'll look for some gasket maker soon.

 

No problem man just glad to be of help.

 

Hmm...I tried using the gasket sealer on the gasket and the noise is still there. I ended up listening carefully and the sound is coming from the oil filler cap instead of the throttle body. It ends up that there is a lot of vacuum inside the engine and the oil cap is trying to be sucked in. If I take the cap off there is no noise when turning off the engine, but if I put it on and rev a little the noise comes back when the engine shuts off.

I did, however, change my pcv valve. My old one actually did not have a valve inside and instead was practically a piece of piping. Is it possible that the old pcv valve allowed air from the air cleaner hose to go into the crankcase and relieve the vacuum, whereas the new pcv stops the air from coming in and creating that large vacuum?

 

I just made a huge mistake...What I thought was supposed to be a pcv valve was not the pcv valve. It seems that it is the breather hose. So I messsed up by putting on two pcv valves...I can't believe I did that.

 

It happens