About a month ago my cherokee developed a whistle that is driving me insane! There is no rhyme or reason as to when it starts. Sometimes it starts while its warming up and other times while I'm just cruising down the road. The noise is coming from the rear of the engine. So its definitely not a belt. I've tried spraying carb cleaner around the intake to see if it was a loose vaccuum line and that had no effect. It'll continue to whistle when on the throttle a tiny bit like when I'm cruising at 45mph in overdrive. Then when I give it more gas the whistle stops. I pulled the throttle body out and cleaned it real good and that didn't help at all. If I pull over and pop the hood to try and diagnose this problem it slowly fades away after a few minutes of idling. So it's a real pain to figure out! This whistle is quite loud from outside the vehicle. When the hood is popped it hurts my ears. Sometimes it only whistles for a short amount of time and sometimes it'll go for 15 or more minutes. If you're wondering it's a 2000 cherokee with the 4.0L and automatic transmission.

I uploaded a 20 second video on photobucket to give you an idea of what it sounds like. As you can see in the video it goes away when I'm on the throttle and it comes back when I'm not. Here's the link to the video.

http://s14.photobucket.com/albums/a3...nt=whistle.flv

If anyone can please help me figure this out I'd be extremely thankful!

 

while driving shift it into N to see if its still whistling. from the video im not sure, maybe something is clogging some kinda line?

 

I'll give that a try tomorrow on my way to work, but wouldn't that be the same as it being in park?

 

mine whistles a lot. its probably a vacuum thing.

 

I have a 2001 limited xj and mine started doing something like that but only when i hit the gas. But i know why mine does it. I went to remove my airbox and i broke the two bolts at the bottom of the air box so now there is two holes down there and they whistle when i give it gas. i figured i would just seal them up when i get my snorkel. Good luck hope it helped

 

What a let down! My jeep has been driving me nuts with this same whistling sound and when I found this thread I thought my answer was close at hand, but no conclusion. If one of you guys who posted on this thread or someone else see's this and knows what the problem is please post an answer.

 

Here's my specs. 2000 Cherokee 4.0 Auto

Let me give you what I know. Sound is coming from the back of the engine, I've used a stethoscope and the sound is coming from the far right corner as best i can tell. I tried tightening the rocker cover bolts a little and still the problem exists. I have a little oil seepage from that area as well, could the gasket be bad and the engine is whistling like a tea kettle from the heat coming internally from that area?? The description Avalance gave is the same as my situation. Most people ive talked to think its a belt that is loose but the serpentine is tight and the stethoscope rules that area out. Any help anyone can give would be greatly appreciated.

 

It should not be a leak from inside the engine to the outside. There is not enough pressure in there to make such a noise. And if there was then you have major blow by and the engine would run like poo.

With that said, you stated that the whistle pitch is affected by throttle input. That tells me you have some sort of a intake manifold leak. That's where I would start.

I know my intake whistles, its just the norm for the 4.0.

 

Thanks for replying so quickly TRS, I'll have to do some more snooping around. The whistle sound is not a low key noise it is ear piercing but only lasts for a minute or two at the most when parked. It occurs intermittently, when the engine is warmed up, and when the engine is not under load (i.e. back off the accelerator). It started doing this last year only when it was below -20 degrees outside. No sound this summer but as soon as it dropped into the 40's it started up again. You can change the sound of the whistle by pressing / depressing the accelerator. It's driving me nuts!! I researched this issue on this site and at least a half dozen other people have had similar problems but no written solution on any of them. I'm hoping someone will read this who has dealt with this problem and help a brother out.

 

My "97 does the same thing,it sounds like a turbo.I don't know what it is(i'd like to know) but i like the noise!

 

The throttle body has been know to whistle. But never heard of it being high pitched.

Gotta love the mood swings the Xj goes through with the season changes.

Edit: Check the Idle Air Control Valve, maybe its the culprit.

 

Ya, this isn't a turbo sound. It sounds just like a tea kettle when it's blowing but amplify that by x10 Its embarrassingly loud kind of like a loose alt. belt

Trs, where is the iac on the 4.O?

 

I ended up taking my cherokee to our local mechanic. He traced it to a hose coming off the intake. I believe there was a plastic fitting on it that was loose, but I'll have to check the repair receipt to get you some more info. Maybe I can take a picture of what was replaced to show you as well.

Of all the problems my vehicles have had this one was by far the most annoying! I know how badly you must want it to go away. Hopefully your cherokee has the exact same problem because I'm sure it's a cheap/easy fix. I'll get you the info ASAP.

 

Sounds like a squirrel has decided to make a nest in your truck and is letting you know it's there. Try sticking a "NOTICE OF EVICTION" on your valve cover and see what happens.

 

Thanks.