Jeep Other

I have a 2002 Jeep TJ Sahara w/65000 miles. When I am driving or sitting still there is a loud whistle from somewhere in the front of the engine. It does it when you let off the gas and quits when you give it gas. I tried listening with a hose but can't seem to isolate it. It is very loud when driving and not wuite as loud at idle sitting still.I'm stumped. I replaced the idler pulley but that didn't help. It also doesn't do it all the time. Please help. Almost forgot, it has a 4.0 6 cylinder engine. And I also changed out the serpentine belt.
February 23, 2007.

Hows the idle speed have you ck'd for a vacuume leak by spraying carb clean @intake gaskets

Feb 25, 2007.
I agree with retireauto, check for a vacuum leak

Feb 25, 2007.
Hi, My Jeep with a 4.0 Has the same whistle, But today I waited until the whistling started, Then I put a 15mm socket with 1/2" Drive on the very back top mounting bolt of my intake manifold and tighten and the whistle stopped, I have been on the road all day and it has not whistled at all. But now I can hear that I need to check my brakes they have a squeak that I couldn't hear over the whistling.

Now it may not be the last bolt on yours, it could be any of them or even all. Also torque setting for those bolts is 24 ft-lbs, I took it to 35 Ft-lbs on a hot Engine, and hopping it will be okay. If you don't have a Torque Wrench then just tighten until the whistle stops or bolt brakes.

You may need to replace manifold Gasket, $9-20 call around. But tighten the bolts will tell you if that is what is making the whistle.

Mar 20, 2008.