HopWorks

I have seen posts here about this before, but never had my suite of questions answered, so decided, finally, to start my own thread.

When I turn my air on shortly after starting my Jeep Cherokee 97 Sport 4.0L 4x4, there is a squeal. At idle, the squeal is pulsed, like not that bad. But when I ramp up the RPM's it's really bad. I turn the air off, wait a minute, and turn it on again. It is less pronounced, but sometimes still happens. I rinse and repeat and it finally stops happening.

OK, sure, I suspected the serpentine belt is loose. I did tighten it and it still happens. One of my questions here is what is the rule-of-thumb for making sure your DIY installed new serpentine belt is at the right tension. Someone told me at the shop I go to that if the tension is right, you should only be able to twist the belt 90° with your fingers and no more. I'm at that level I think. Maybe I'm just too weak? lol.

Anyway, what are the other issues I might consider? Is it the compressor? I just had my air done and the shop didn't notice any leaks or issues with the compressor. And the air is good and cold, even in my hot Arizona summer environment.

Could it be the quality of belt I installed? Would a better aftermarket type eliminate this issue?

I'm at my wits-end with this. It's annoying, but I tolerate it because A) I need the air, and B) it's my Jeep and I love her and tolerate the little issues.

I have another issue with the door locks pulsing over and over while I'm driving, but that's another tolerated issue. lol. Had to throw that in.

Any and all ideas would be greatly appreciated. Along with recommendations for new gear/parts, even a better aftermarket serpentine belt.

Thank you guys on the best Jeep forum ever!!!! for your time!

Eisenschwein

Is it an old belt? When they get old, they get "glossy" and lose friction/grip. Especially if it has been squealing... the AC is sure to have put a nice spit-shine on that belt by now.

Aside from that, could be something dragging the belt, like a bad AC compressor or the Water Pump or Alternator adding to the drag. I see a lot of 4cyl cars that will squeal belts with the AC on, or even lights and heater at the same time. That 4.0l has plenty of power. Are you running your lights at the same time as the AC?

HopWorks

Yes, running my lights in the morning when it happens driving down the road, but not in the driveway, but it still happens around 12pm when I do not turn on the lights. And if it matters, it happens more after a rain, which supports your thoughts about a "spit-shine" on the belt by now.

Tested the alternator, and after 18 years, it is still working great. At least as far as the test analytics are concerned.

Got any shop-tricks at knowing if my serpentine belt tension is right? If I can go after that with a new belt, then I can go after the other systems.

xjchrisc

Mine has done the exact same thing for the three years I have owned it. It has not done it much this year though. One thing I have noticed is that if the fan speed is on low when I start the jeep it never squeals. If the fan speed is on high it is a 50/50 shot.

Eisenschwein

I've never had trouble with the tension. Most belt systems have a spring on the idle pulley that is somewhat of an auto tension. I kinda doubt that is your problem. And ya, it will happen more in the rain... I had a 4cyl Nissan pickup that would squeal like crazy if you looked at it wrong, but the little motor and alternator just weren't big enough to keep up with the draw.

New belt might be worth a shot. It would be interesting to see if you can get it to squeal with the hood up, to see where it is doing it. I'm guessing it is on the alternator. Alternator is a small pulley with big responsibility. Belt dressing sometimes helps but usually a new belt is the best.

GregGA

First, get a new belt. I recommend Gates. Last one I got was made in Mexico, but no problems in over a year.

Second, buy a Krikit II belt tensioner gauge. I had Napa order me one, about $15. You need to tension a new belt to about 180 lbs, and this gauge will show you how far you are off using the "Trumb press method".

Let us know how it works out.

HopWorks

OK Will do. I'll get the new belt tomorrow and order that tension gauge. Thank you!! More when I know it.

Jeep Driver

Could also be your harmonic balancer.

GregGA

Cool. Will stand by.

cobrastang96

I had similar issues and I thought it was the compressor as well, but the idler pulley bearings were shot and eventually broke the belt, replaced idler pulley and no squeal. Just my 2 pennies.

amorth

I had the same problem a while ago. Replaced the serpentine belt and all is good now

kick_rocks

My 96 has same problem and I do suspect a belt since I have a squealing sound when the engine is cold. Not sure if its the idler pulley or something else. But when I turn on the air or the heat I also get a loud tick or snapping sound also every couple of seconds and it goes away if I remember correctly but it sounds terrible at first. Any comments on that are quite welcome!

extrashaky

I'm a couple of days late to the party, but...

If you haven't already bought it, skip the Gates belt and get a Goodyear Gatorback instead. There's nothing wrong with the Gates, but the Gatorback is about the best belt you can get. It's made a little differently from a regular belt so that it's about as close to slip-proof as you're ever going to find. That thing will grip even when it's not tensioned properly.

And also get that Krikit tension gauge. The deflection test (where you twist the belt) isn't reliable. It's supposed to be a lot tighter than most people expect. If you have a factory service manual, you should check it for the correct tension. It will probably be the same as my 2000: 180 to 200 lbs. ft. for a new belt and 140 to 160 lbs. ft. for a used belt. You tighten a new belt a little more because they stretch and lose a little bit of tension as they break in, but you want to make sure you don't overtighten a used belt.

It amazes me how many "professional" mechanics basically just guess at the correct tension for lack of a $15 tool, when there are specs right there in the service manual.

El_Guapo

After you do enough of them with the gauge, you find that you're pretty accurate without the gauge.

That said, the Krikit is a good tool to use for a baseline, but still not exactly the most accurate gauge out there. When compared to a higher end tester like a Kent-Moore, it is usually off by 10-20 lbs.

HopWorks

Late to the party is just fine. There is plenty of action until dawn! At least that is what I tell my tardy friends. lol

Thanks for the suggestion. I'm all about numbers and need something more than "a good feel" to be sure. I noticed a post about a more accurate tension gauge, but I'm sure the one you suggested will be better than my inexperienced fingers. I also appreciate your belt suggestion. That is EXACTLY what I was looking for with this thread.

And I wondered all sorts of ways about the compressor. It only happens when I run colder, or when the humidity is up. When at running temp, I have no issues with squealing at all. And the air runs cold.

STILL... last I checked this issue when I replaced the tension pulley, the tension pulley was making all the noise. It's only been a year but could it be the pulley again?

I wanted to say that I am amazed how you Jeep experts took the time to respond to my question/thread, and again, said it before, it's one of the reasons I post questions here. You guys and gals are awesome and I appreciate your time with your replies!!!

No one said anything about my power door lock issues though. I threw that in hoping for a 2 for 1 bonus. It absolutely SUCKS now! It's like a 5-year-old going nuts on the power locks! Only relief I find is banging the control on the passenger side with a socket wrench I keep in the front seat. LMAO. Where can I find factory control units for those front seat panels other than a junk yard?

YOU GUYS ROCK! THANK YOU!!!!

I say Tension Pulley, You say Idler Pulley. TomAYto, Tomato. lol