loud whining sound... please HELP!!

i own a 2001 cherokee with 4.0. i am driving along and hear a super loud high pitched whining sound after the engine temperature reaches about 190 degrees, give or take 10 degrees. sometimes it only occurs when i take foot off the gas and goes away when i step on gas, other times it only gets quieter when i step on gas. THIS IS NOT A LOOSE BELT! i know that for a fact. it sounds like it is a vacuum hose leak, but i have no idea where to look. if i pull over and open hood to try to find where it is coming from... it goes away. put the hood down to continue driving. and it comes back. If you have any info, please post and help me out because not only is this annoying, it is also embarrassing when i drive past people and my truck is crying like a little baby. :hang: i don't know if this could be connected to this problem, but i also have a problem with my transfer case. i am stuck in 4wd all the time. i had a friend suggest that my vacuum actuator on my T-case could be dysfunctional. (vacuum hose leak...vacuum actuator... same problem??? idk) any help is appreciated. if i didnt explain something well or if you have another question, just let me know. thanks for even taking the time to read

Tell your girlfriend to stop riding with you, no more whining.

NAAHH seriously. Try it while sitting still? Put it in park or neutral and increase the RPMs to see if it is engine or drivetrain related.

A few things that could be causing the whine you describe...

Bad bearing in the idler pulley.
Do you have AC, and does the whine occur when on? Perhaps a bad AC clutch.
Bad alternator. Any charging issues?
Again, don't totally rule out the belt. If you do not have tightened to factory specs, it will cause a whine. Also if you recently replaced the belt, some aftermarket belts will stretch and cause the whine. I tried a NAPA belt, and had a bad whine with two of them. Replaced it with an OEM belt and the whine went away.

That's all I've got...

You sure its not you t-case whining for mercy since you are driving around in 4wd?
I hope you pulled the front ds...

there is no vacuum actuator on your tcase, the only hose connected to it should be the vent tube. do you have a crossmember drop kit installed? if so the linkage might be pulled too tight since the tcase is now further away from the body.

To adjust 4x4 shifter linkage:
1. Loosen adjustment bolt
2. Place shifter and t-case in 4low
3. Pull plastic trim ring around shifter, place a 1/8 drill bit in between shifter handle and shift gate, bungee in place
4. Tighten adjustment bolt

T-case should shift great after this! However I would reccommend replacing the fluid, as you have probably cooked it. Look for metal shavings in the old oil, and keep your fingers crossed

Enough fluid in you power steering?

i do have a/c but it is january in MN so im never using it. my battery and alternator work just fine. i have been able to get the hood open when it is going on and it sounds like it is more toward the middle/back of engine, not toward the front where the belts are, and this is a different sound than if it was a loose belt. i have no crossmember drop kit installed. it started to happen after i installed my lift. a 4 inch lift and 31x10.5. i didnt need to install an sye because there was no vibrations coming from the driveshaft. i plan to drop the t-case regardless tho. i will check all the fluids tomorrow morning and get back to you guys. thanks again

oh yes. on more thing... i have a 242 TC

Check your manifold bolts. I get the same noise that you're describing every couple of weeks due to the top rear (closest to firewall) manifold bolt that continually loosens itself. I've torqued it to factory specs every time it happens, but it always backs itself out. Come warm weather the manifold and bolts will be replaced, but for now I just tighten it every few weeks.

HTH.

OK, if it's making the noise when sitting in park or neutral, rules out the transfer case. Are you stuck in 4WD Part-Time, or 4WD Full-Time? It won't hurt anything to be stuck in 4-Full Time with the 242 TC. If you haven't installed the TC drop yet, your linkage shouldn't need to be adjusted. And, if you're not getting vibrations, I wouldn't lower the TC at all...just puts it closer to harm's way. Keep looking for vacuum leaks or manifold leaks for the noise then.

im having this EXACT same problem. its not a belt...it definitely sounds closer to the intake or the rear where the vacuum lines are....and it only happens when its cold out to me.. im thinking its a bad intake manifold gasket

try this...get it to whine, pull over quick and before it goes away try and grab the intake manifold and move it up and down...my whine changes pitch when i do this...im going to do a gasket and go from there... $15.99 at a local napa