high pitched noise from engine compartment - vacuum leak

[airkooledchris]

The other day I was driving when I suddenly heard this loud high pitched noise coming from the engine compartment. It's an unnerving sound and I just couldn't get an exact spot of origin when I first checked.

My initial thoughts was the fuel pump trying to overcome being partially clogged or something in the distributor (electronic ignition).

I finally had some time to think about it and sure enough, it's a vacuum leak at the intake runners on the 3/4 side.

I took some carb cleaner and sprayed down at them, and as soon as I did the idle just plunges for a second and then returns to normal. Im not sure why it doesn't make the idle race higher as it sucks in the carb cleaned, but it's an instant result.

So if your searching the forums for high pitched noise, or squealing sounds coming from the engine compartment like I was earlier - put this on your list of things to check.

I don't have a spare intake gasket so hopefully it just needs to be tightened up, otherwise ill be without a vehicle for a few days.

It's pretty bad though, as I was getting random hesitation and bogging down of power this morning when the noise started up again.

[Westfabulous]

Gently put a pair of adjustable mouth pliers on it and rotate it until the whistling stops. This vacuum leak might cause the RPMs to surge higher when the engine is cold and the mixture is rich, but as the engine warms and the mixture leans, the extra air will be an unwelcomed guest, and will cause the issues that you are seeing.
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