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Discussion Starter · #1 ·
okay -- i tried for hours on my own research with talking to ppl, YT videos and searching on here but no luck.
Here is what i have. When i start my YJ the alt belt squealing is happening -- used to be for 10 seconds and now its getting longer and louder. The other things I notice is that when this happens my alternator is only reading 8V or so on the dash. As soon as the squeal stops, the alternator jumps up to 13-14V - everytime.

Since the squealing stops i do not think it is anything to do with the alignment of the Alt pulley to the fan pulley, they do look very much in line when i eyeball it but also why would the squealing ever stop if they were out of line.
I do not see the belt slipping at all and am pulling the alternator as tight as i can to get the belt tight.

Replaced the Alternator 3 years ago, and also replaced the alt belt with a heavier duty one from Napa that was supposed to stop the squeal but it has not.

Just to be sure yesterday I started it up and had the squeal. Stopped the jeep and then took the alt belt completely off -- started up so quietly and beautiful -- no squeal at that point. That makes me sure that is on the Alt side and nothing to do with the PS side. Of course when i put the belt back on the squeal came back. I have not tried to use any belt dressing as i told to not do this.
Below is a terrible drawing of my belts in this YJ with no AC and no Idler Pulleys at all. Any thoughts on what I might be dealing with here and how i can fix this?
Could the added tension from the Alt belt be causing friction on the Fan Pulley and then maybe some older bearings in the fan are what is causing the squeal? If so can i replace the fan unit or just the ball bearings in there?

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Here is a pic of the alternator side of my engine:

Automotive fuel system Automotive tire Motor vehicle Automotive exhaust Automotive design
 

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Are you sure it is slipping on the alternator pulley, and not down on the balancer pulley? Easy way to tell would be to watch the belt while someone else starts the engine. If the belt is moving, it's slipping on the alt pulley. If not moving, it's slipping on the HB pulley.

Maybe try a new pulley and belt. And check to be sure you have the correct belt. My alternator belt is a smaller cross section than my PS belt.

I don't know if it means anything, but your alternator pulley looks different than mine. Yours looks aluminum, mine is steel. Mine is also a double sheave, no idea why, it never had a second belt. Probably means nothing.



 
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Here is another photo. Notice down on the HB pulley - the alternator pulley is a bolt-on sheave that is just a sheet metal affair. Easily replaced without pulley the dampener. Or removed for just cleaning and resurfacing.

 

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Discussion Starter · #4 ·
Bill - thanks for the solid reply and pics.. very helpful.
Can you tell me what you mean by the HB pulley? I am not familiar with that HB you are referencing?
I will also note that after running it for about a 45-sec to a minute I tried to take the alt belt off and the pulley on the alt and the belt that was touching that pulley were SO hot that it almost burnt my hand. I don't know what that tells me but that didn't feel like it should be that hot?


Here is another photo. Notice down on the HB pulley - the alternator pulley is a bolt-on sheave that is just a sheet metal affair. Easily replaced without pulley the dampener. Or removed for just cleaning and resurfacing.

 

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Sliding makes it squeal. Sliding will also cause friction. Friction creates heat. Heat burns hands.

Don't overthink it. Change the belt. It's the cheapest and best way to find out if that's the problem since you already tightened it up and it still did it.
 

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Discussion Starter · #7 ·
Haha -- thanks for the note on what you did to solve it -- like you said I do not think its the belt at all but that is something I will look closer at... i love that your friend got tired of hearing it and bought you a new one. good friend.

I had the same problem. Swore up and down it wasnt the belt since it was less than a year old. Still squealed on start up no matter how tight I made it. A buddy got tired of hearing my squealing in the trail and bought me a $4 belt lol The noise instantly went away
 

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Discussion Starter · #8 ·
Thanks man -- i will try that easy and cheap fix before i got forward -- but just did not think it was my belt b/c i really put that on 2 years ago and since i only drive it in the summer that's less than 2K miles on that belt.

Sliding makes it squeal. Sliding will also cause friction. Friction creates heat. Heat burns hards.

Don't overthink it. Change the belt. It's the cheapest and best way to find out if that's the problem since you already tightened it up and it still did it.
 

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Been a member of the belt squeak and squeal club on and off for decades. If it starts up loud and goes away after running a minute it's usually belt. If it chirps at you intermittently while running but doesn't stop for a while it's usually a bearing.

If your belt was offline or rubbing you would probably see some odd wear on it while you had it off.

I hope a cheap belt fixes it.
 

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Discussion Starter · #10 ·
This is one club that i want out of immediately! I cant take it --- thanks for your reply --

Been a member of the belt squeak and squeal club on and off for decades. If it starts up loud and goes away after running a minute it's usually belt. If it chirps at you intermittently while running but doesn't stop for a while it's usually a bearing.

If your belt was offline or rubbing you would probably see some odd wear on it while you had it off.

I hope a cheap belt fixes it.
 

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Bill - thanks for the solid reply and pics.. very helpful.
Can you tell me what you mean by the HB pulley? I am not familiar with that HB you are referencing?
I will also note that after running it for about a 45-sec to a minute I tried to take the alt belt off and the pulley on the alt and the belt that was touching that pulley were SO hot that it almost burnt my hand. I don't know what that tells me but that didn't feel like it should be that hot?
HB is harmonic balancer. It is the pulley on your crankshaft. The second pulley (sheave) is bolted to the face of the harmonic balancer, and that bolt-on pulley is what drives your alternator.

That fact that the alt pulley got hot is pretty solid evidence that it is slipping at that point.
 
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The squeal is a glazed belt or it ain’t tight enough. The battery could be weakening presenting a higher load to alt field at startup.

no mystery stuff going on. It’s a vbelt
 

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Discussion Starter · #13 ·
Appreciate the reply -- even though Im in my 40's this is my first real ride that i ever worked on so i am still very much learning how to handle stuff on my own like this. I promised myself if i got this jeep I was going to work through things like this and not just take to my mechanic, so far i have been true to my word so i am continuing to work through things like this...

The squeal is a glazed belt or it ain’t tight enough. The battery could be weakening presenting a higher load to alt field at startup.

no mystery stuff going on. It’s a vbelt
 

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Discussion Starter · #14 ·
Excellent info Bill -- didnt know the names of those items that you mentioned below so that has taught me a good bit on this today. It would seem like i could swap out both the HB and the Sheave if i wanted to, is that correct? Im not saying that this is my problem with this issue I am having but just more for me to understand that i could possibly do it if needed/wanted to.

Someone else did mention that the heat I was feeling is a good sign of slippage so i am going to grab a new belt and get that thing tighter than before and see how that goes.
 

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...It would seem like i could swap out both the HB and the Sheave if i wanted to, is that correct?
You can, but it gets a little involved. The HB is pressed on, takes a puller to remove and another tool to install, and the HB is also integral front crank shaft seal. So it isn't something you do just for the heck of it. Harmonic balancers do wear out, the rubber starts breaking down. I put a new one on a couple few years ago, when I was doing the timing chain. That outer sheave just bolts on, but when I was working on mine, availability of a new pulley was questionable.

I think it is clear that isn't your problem, but just for edumacational purposes.

Another thing about belts though - sometimes you get new belts that are old and past their prime. They get hard and lose friction, just exactly like tires do. And belts often hang on a peg for years before they get sold. I'd just get a new one, and if that pulley on the alt is aluminum, I would get a good steel one, but that's just me.
 

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The part of your belt that does the driving is basically the bottom surface where is is squared off has to be able to wedge into the Vs of the pulleys tightly. The sides do not really do much. It is technically the side that does the driving but it is the part right at the bottom of the side if that makes any sense.

Serpentine belts wear the same way. They have to be able to grip near the bottom of the groove of the belt and not bottom out in the pulley or have too wide of grooves in the belt. You do not see them wear out this way as often but it can be difficult to pick up on a slipping serpentine belt. I recently had to help one of our young pups that put something like 3 or 4 alternators on a focus, we tested Pcm circiuts, field wiring, voltage drops, etc. to find that the belt was slipping.
 
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V belts wear along the sides, and sink deeper into the pulley. At one point, they're still intact but no longer make secure contact with the sides. The belt may look good, but that does not mean it's not worn.

There is a difference in price and quality. A few bucks extra is worth it for durability.
 

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Discussion Starter · #19 ·
Problem solved but i feel like a dumb *** at this point.... the time i spent looking at different areas where the squeal was coming and then to make this whole post and now to have the problem be solved the way I did last night.
Stopped by Adv Auto and picked up a new belt.. got home and tried to put that belt on, it said it was for YJ but it didn't fit mine. So i looked at the belt I had on and it is still in great shape, then after reading a few your replies about it probably be a belt slipping issue i pulled the Alt as tight as i could and then also used a crow bar to get that little extra pull and tightened it. Jeep started beautifully. no squeal whatsoever.... so this whole issue looks like I just didn't have my ALT pulled tight enough. Thanks again for your replies --
 

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Discussion Starter · #20 ·
GM Bill -- one part of your note below that caught my eye -- you mentioned the pulley on the ALT -- is that a part that i could swap out ? I didn't look at that very closely to see how that pulley is attached to the ALT but that is good to know that that part is swappable instead of having to go buy a new ALT. Thanks!


You can, but it gets a little involved. The HB is pressed on, takes a puller to remove and another tool to install, and the HB is also integral front crank shaft seal. So it isn't something you do just for the heck of it. Harmonic balancers do wear out, the rubber starts breaking down. I put a new one on a couple few years ago, when I was doing the timing chain. That outer sheave just bolts on, but when I was working on mine, availability of a new pulley was questionable.

I think it is clear that isn't your problem, but just for edumacational purposes.

Another thing about belts though - sometimes you get new belts that are old and past their prime. They get hard and lose friction, just exactly like tires do. And belts often hang on a peg for years before they get sold. I'd just get a new one, and if that pulley on the alt is aluminum, I would get a good steel one, but that's just me.
 
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