Whistle at idle - vacuum leak, induction side

[RichieRoo]

Well, everyone seems to be thinking along the same lines... some kind of liquid.

I might try a little WD40 or silicon spray perhaps that won't damage anything
back there. I should only need a little to identify it - I reckon the liquid will
momentarily block the leak a stop the whistle for a split second allowing me
to narrow my search area.

I'll give it a go and report back. Thanks for the ideas.

[GeneW]

Originally Posted by RichieRoo

Well, everyone seems to be thinking along the same lines... some kind of liquid.

I might try a little WD40 or silicon spray perhaps that won't damage anything
back there. I should only need a little to identify it - I reckon the liquid will
momentarily block the leak a stop the whistle for a split second allowing me
to narrow my search area.

I'll give it a go and report back. Thanks for the ideas.

I'd go with Propane or MAPP gas, from a torch. Just open up the valve and let the gas swirl around spots that you believe are leaking.

I used to work on vacuum systems using helium and a mass spectrometer coupled to the output of the pump. You would "squirt" a little bit of helium into various sample areas and watch the results.

A better way than using your ear is to use a tach or use feedback from the Oxygen sensor. I am not sure if a Scanguage will report Oxygen sensor readings but if so it's really simple to watch the O2 drop each time too much hydrocarbon gets in.

The best way to do this is to find "suspect" areas, section them off into sectors and expose each spot. For example, if you have a round fitting divide the area around it into quarters and expose each quartered area around the fitting for a few seconds.

Give the car about ten seconds or more between "exposure" to hydrocarbons to restore its equilibrium, especially if you're using RPMs instead of O2 readings.

Take notes of where you saw changes, then later re-test the areas in more detail. I would avoid cranking up the gas through unlit torch or slathering on fluid because you could find two leaks at the same time, which will confuse you.

I'd avoid anything with silicon - could poison your catalytic converter.

Gene