I have an '85 CJ7 w/a 258.  It periodically makes a very loud whine/whistling noise coming from somewhere near the carb(?).  It happens as the engine warms up.  Ususally when I first put it in gear start driving.  It decreases/stops when I accellerate or rev the engine, but gets loud again as I get to speed.

I runs fine, but this gawd-awful noise is more than a bit annoying.

I tried to isolate it, but am not having any luck.  It usually stops before I can get stopped and get the hood open.

I am thinking it is something in the vacuum system...any ideas?  

Not familier with the engine, but I have a 91 YJ 2.5L and it whistles like that as well, but I believe it is just the serpintine belt. Could be a belt thats squeeling.  

I don't think it's a belt.  It is coming from farther back.  I'll spray them with some belt dressing, just in case.  

Nope...not the belts.  

hmm, other thing I would think of is either vaccum hoses, from the air intake possibly arn't connected tight enough, or maybe a air leak in the carb, maybe get some new gasket's for it, if of coarse it sounds like it's comming from there.  

Try spraying a little brake cleaner at the base of carb
you might have a vacuum leak, if the motor revs up you do. Carb could be loose and when the throttle cable pulls on the linkage it opens up at the base gasket?  

mikecjeephemi:
Try spraying a little brake cleaner at the base of carb
you might have a vacuum leak, if the motor revs up you do. Carb could be loose and when the throttle cable pulls on the linkage it opens up at the base gasket?

Having already replaced 20' of vacuum line, I tried the spray test w/promising results.  When it warms up later, I'll try torquing down the mount bolts a bit.  If that doesn't work, I'll check the mount plate and replace the gasket.

Thanks.  

Hi, I have the same whistling on my 2001 Jeep Cherokee with a 4.0 I removed my serpintine belt and the whistling is still there. I have looked for vacuum leaks and can not find anything, Checking around on the Net and it seems that others have the same whistle.
I am told Throttle plate or Idle air Control valve. I was also told Replace Carburetor but I don't have one so that can't be it on mine.

I wonder what would be the same part on both the 4.0 and the 258, maybe Idle air Valve.

Please let me know if you find out what it is, I'll keep looking.  

Hey, I was just on another Forum and found this post, I am going to give it a try.


>>I just bought mine two weeks ago - it is an intake manifold leak. My mechanic tightened the bolts...but it only helped for a couple of days. On mine if you drive it for a while it will start...at idle...then you apply gas and it goes away. The next time it happens, pull over...open the hood...and while it is whistling pick up on the intake manifold...mine stops...then push down a little and it starts again. The dealer will replace the gasket for ~ $300. I plan on taking it in soon to have it done...<<  

thats the vacumm leak....and a big one.  

hey mrclevis taking the serp belt off isnt a good thing to do and run it maily due to water not circulating it will lock of your engine if you let it warm up while tinkering with it somtimes guys can forget and it gets too hot and will lock up your engine.

why dont you try and chang the gasket yourself aint all that hard the bolt shouldnt be seized. the manifold gasket doesnt cost all that much at the most 20 25 bucks and they want 300 it aint worth it. their basically charging you for your time. check autozone or advance autoparts web site you can price them on the site.  

i have a winning noise with my jeep and i figure it out that i had a diode in my alternator that was shroted out.  with a shorted diode it will wine but if its only one you wont notice a voltage drop. so try poping ur belt off the alternator and if it goes away then you know its a diode in the alt.  

All right, today I waited until the whistling started then I pushed on the intake manifold and pulled up but there was no change. Then I put a 15mm socket with 1/2" Drive on the very back top mounting bolt and tighten and the whistle stopped, I 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.  

lol.. it never ends!