I have a new problem with my 00 WJ. I have an intermitant loud whistling sound during moderate acceleration that sounds like a vacuum leak, but doesn't show the symtoms. No power lose, no rough idle, no codes set, no loose or cracked hoses. It is loud enough that pedestrians look at me. It goes away but comes back every so often. Could it be a bad bearing in the drive belt system? When it appears, I've pulled over, opened the hood and tried to find it. It only seems to happen in gear and under mild acceleration, ie; low vacuum conditions. It doesn't show up under high vacuum, such as going down hills.

I am at a loss for ideas. Anybody please give me suggestions.

 

I had a whistling noise similar to that when I had an aftermarket air intake...removed it and the noise is gone. IDK if you have one of those or not, but that's all I can think of.

 

My air filter setup whistles. I think a lot of them do on these rides. I had another jeep that whistled when it warmed up and it ended up being a loose intake manifold bolt. It wasthe one closest to the firewall. My jeep whistled with the intake and nowdles even more sincei ported tb. Sounds normal to me

 

Thanks guys! What I needed was a fresh mind! I will check the manifold bolts. Never thought about them and the idea sounds right. I've only had the jeep for about 90 days, but it seems to idle just a tad rough in gear. I have checked all the normal things and haven't found anything abnormal. The entire thing was detailed before I got it, underhood and all. Whoever did it put a complete list under the hood as to what was done, even plugging the left front tire!

This car is from Pennsylvania and I think belonged to a soccer-mom. The cigarette lighter wasn't even used! The only things wrong with it are a few paint scratches that were touched up and the driver's armrest has some cracks in it. I only spent $4200 on it and I don't think I could've done better!

Now to beat the crap out of it!

 

Update. Upper 5 manifold bolts are tight, however it just started raining and I'm too old to be lying on my back on the ground in the rain. In my younger days, I changed a transmission in a snowstorm and didn't think twice about it. My garage was built in the 20's, has a gravel floor, and I'd have to fold the mirrors to get it in, plus at present it's full of storage boxes thanks to my wife!

Just remember; That mysterious noise will not appear in the presence of a mechanic!

 

That's always the case Dave. "Mechanic cannot duplicate customers complaint". I guess we just made it up?

 

I know this is an old thread but I did not see a resolution. I also had this problem ("tea kettle whistle, with a warm engine, when picking your foot off the accelerator).

Tightened down the throttle body. No difference (but was surprised to see it turned another 1/8 a turn). Was about to whip out the TB cleaner but decided to give a little tug on each of the manifold bolts. The back manifold bolt turned 1/4 turn easy. Snugged it down a tad more. Just took her for a drive on the freeway to replicate the issue. All solved! I will say for myself and others, I'd still suggest replacing that gasket sometime in the near future, if not only for the reason that if that one bolt walked out a bit, no harm in taking it all apart and doing it right.

 

glad it worked for you as well man! this was one of the first issues of its kind I had to deal with and it was a great relief to fix it. for future people having this issue, taking some spray cleaner like carb clean or brake cleaner seems to be the best way to locate where the leak is. and most of the time if its a high pitched whistle (almost like a beeeeeep noise) it will be an air leak around the intake manifold or throttle body. snugging those bolts down is always a good idea to try but you never want to over tighten them because that cast aluminum will indeed crack if you over do it.


This fix should be added to the stickies list. it seems to have become a common problem with these jeeps.

 

Sorry guys! I forgot to come back with a resolution. It seems that it was an idler pulley because after a couple of days it went away, but after a month, the stationary idler pulley started squealing viciously. It's very odd that it sounded like a vacuum leak but wasn't.