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Discussion Starter · #1 ·
Hi all,
I have a rather load whistle sound that comes and goes. If I rev engine it comes and goes and sometimes while idling it will come and go. It sounds like it is coming from under the jeep.

My guess is it is a vacuum leak. Any ideas? I'm going to try and find it tonight.
Thanks WW
 

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I had a big leak on the PCV tube, the one in back that goes from the elbow on top of the valve cover to the intake manifold. The short rubber hose that connects the tube onto the intake split right up the side.

There was a big opening there and the intake was sucking a lot of air directly.
Really pretty loud whistle because there was so much air getting pulled in the intake manifold.

It didn't throw any codes, but you could hear the whistle and the RPMs would not come down no matter what!

Replaced the the defective hose. Problem solved. Whistling was gone and RPMs come down pretty quick after taking my foot off the gas pedal.

There is another hose going from the front PCV valve to the air filter box. Look there too.

The other vacuum lines are much smaller and would not make quite as loud a whistle as the big ones on the PCV fittings.

If your RPMs are racing with your foot off the gas, I would guess the PCV hoses might be a good place to start looking.


Red rectangle on the photo shows which hose connector split, causing the big leak on the intake...
(Yes - the throttle body is covered with tape. I was replacing the valve cover gasket and did not want junk getting in there. The photo was just used as the example to show where my problem was found.)



Good luck!


Let us know what you find out.
 

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