i got a question, i have a 2000 wrangler sahara and my engine makes this squeeling noise, and i just got the belt changed, it only makes noise when the engine is cold, but when the engine warms up it goes away, any suggestions would be helpful, thanks  

Is it a like a high pitch whistle?  I get the same thing when its below 20 or so.  After say 5 minutes it goes away.  I just bored and stroked my 4.0.  It was cold the very next day and it started doing it again!!  I always thought it was an intake leak.  When it warmed up, everything expanded and sealed up.  The onlt thing I can think of is that the incoming air is whistling by the little spot in the side of the throttle body which I believe is the idle control.  

Hello try greasing your idler pully.I had this problem on my 1998 wrangler, the idler pully was'nt worn but there was'nt any grease which caused a squel.Also check your belt for uneven wheare as a bracket could be bent or even a pully, good luck with your fix.  

or it could be that there's a slight amount of moisture on the pullys and belt, from sitting and cooling down, this will cause a slight squeak until things warm up.  

maybe its a low quality belt, i have noticed that sometimes that makes a diference. try a Goodyear Gatorback, i have good luck with those. I have also changed the idler pulley on my 4.0 a couple times.  

We just did a stroker on my sons 4.0 xj. All went well except for belt squeal. After buying the best belts and and much research we found that one of the pullys was not alligned with the rest. It was not easy to measure and establish how far out. It was slightly scewed. By adding shims we finally got rid of of the noise. All of this took a couple of weeks which included all the investigation... Good luck  

i just got the belt replaced and im new to jeeps, so i dont know much about the motors, where exactly is the idler pully? and what kind of grease do i use? its a squeeling sound, so any more help would be helpful, thanks  

I know its not a belt issue.  I know what belt squeal sounds like.  The whistle I hear is what it is, a whistle.  It changes with throttle position, not rpm.  

benj...have you checked for vacuum leaks?  

Yes I did.  No fluctuation at idle.  I siliconed the intake on both sides of the gasket and made sure it didn't squeeze the gasket out when torquing it down.  The funny part is that I had the noise before rebuilding the motor.  Like I said its only when its real cold.  I started it in the morning when it's like 20 or so and nothing.  Seems to be on single didgit temps.  

cm2000, the idler pully is to the left of the alt. pully right of the a/c pully. it's easy to tell from all the other pullies, it's smallish in size and just seems to be there. the others work the alt, a/c, p/s, fan-water pump lower pully is crank shaft i would guess that you unbolt it? i've never removed one. or maybe get a small diameter hose, like aquarium tubing, and fit it onto your grease gun and squirt a little behind the pully.  

thanks for your help, ill try that, but if that doesnt work, should i just replace the pully? or get a new belt again? any other suggestions would be helpful  

i tried greasing the pulley, it didnt work, the noise is still there, so i dont know what else to do, should i replace the pulley or get a higher quality belt? if anyone has any other ideas on how to get rid of the noise, thanks for the help  

Hey don't know if this helps-
     Those pulleys have sealed bearings, mine have done everything from a loud squeak to a more quite dragging noise. If you take one off you'll notice the black seals, use a small screwdriver and pop the seal off one side. pack the bearing like you would on on a wheel replace the seal and it will be silent again. while this is not a permanent fix it will work for 6 or 8 months, if that in fact is your problem!  
    On the other hand when it is less than 40 degrees outside I get a loud noise when I'm going down the road. This one has nothing to do with the motor, I can let the motor warm up and it will still do it, if the jeep hasn't moved in a wile. I cannot pinpoint this one! It almost sounds like the head pipe is squeaking (rubbing on)  something but it's not!! And 8 or 10 miles down the road it's gone!

Hope that helps!

-Cliff  

think the water pump could be making the whistle sound, i've heard some odd noises from worn out water pumps.