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Basic Maintenance - 4.0L serpentine belt tension adjustment

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#21 ·
Alright, so you cannot just tighten that one main bolt to tighten the belt? I was trying to tighten it today and it took forever...

Just wanted to make sure it is necessary to loosen all those other bolts...
 
#22 ·
mightydog78 said:
Alright, so you cannot just tighten that one main bolt to tighten the belt? I was trying to tighten it today and it took forever...

Just wanted to make sure it is necessary to loosen all those other bolts...
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If you try to tighten the adjustment bolt without loosening all the other bolts you will most likely snap it off. Then your going to be heading to the dealer :)
 
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#23 ·
I tightened mine up and stopped the squealing noise, but it came back after I drove it around for about 10 minutes. I have repeated this several times and the squeal always comes back. The tensioner is about as tight as it will go and it seems like there is virtually no play in the belt. Also, since I have a 2.5l, my setup is slightly different. I have only seen two bolts, one to loosen the pulley and one to move the pulley up and down.

Maybe I just need to put a new radio in that I can turn up loud enough so I don't hear the high pitched scream.
 
#24 ·
Quality of the belt matters. As does proper tension. I replaced mine with a cheap belt from advanced auto a couple months back, and could not get the squeal to go away. Fist, I broke down and bought the NAPA tension gauge. Man, I had sucker on there tight. Or so I thought. Turns out, it was below 100lbs. Tightened it up to spec (160-180lbs), and the squeal quietened down some but was still there.

Thought maybe it was coming from the tensioner pulley. Only $12 so I figured why the heck not. Nope, still there. Finally I broke down and ordered a Goodyear Gatorback belt, thinking maybe the issue was the belt, as it was the common denominator and cheaper/easier than replacing pulleys. Got it on, tightened to spec...purred like a kitten. Had to retighten it after a couple days once it had stretched some. But no issues now.

You can pick up a Gatorback off eBay for like $10-12. If you're having squealing issues, just get the tension gauge and the belt and be done with it. Just my $.02
 
#25 ·
I wanted to just add on to this thread since I have had a few issues and thought that this might help someone in the future. First, I ordered a Gatorback belt off of Ebay. It stated it was for a Jeep with a 2.5l engine with a/c and power steering.

I was super excited when I got it and ran into the garage to replace my old belt. After routing it around the pulleys in the same way, I realized that it was longer than the belt that I had on there. I think that the reason for this may be that I had a Jeep garage in Jacksonville install a/c in the Jeep. (It is my daily driver and I have to wear dress clothes to work and it gets way too hot in the summer). Anyway, I thought that since the a/c was installed in the same manner as the factory ones that it would match. It did not.

While I was trying to tighten the new belt every last little centimeter I could, I also managed to snap my tensioner bolt. So as a note to all, when you are tightening the bolt and it doesn't want to go anymore, stop. I had to go to the dealership to get the new bolt because they do not sell it anywhere else. You could also maybe find it at a junkyard too. Part number 6503198 CAB3F2BOLT and it is about $13.

I took my old belt to Bennet Auto Supply and they measured it out at 95". The Gatorback belt I ordered was 96". I went ahead and purchased another Gatorback belt from Bennet that was 94.5" because the 95" belt had the tensioner pulley maxed out. I replaced the tensioner bolt which was not terribly hard and mounted the 94.5" belt and now my Jeep sounds great.

So, the things that I would do differently would be to take my old belt off first and have it measured, and then order the proper belt accordingly. I saw three different Gatorback belts and they all stated that they worked with the 2.5l engine. I think the only true way to know is to measure the old one. Also, do not overtighten the tensioner bolt. When it says stop, it means it.
 
#27 ·
This is a great post!!!!

I'll be trying to adjust the tension on my serp belt tonight for the 4th time, so that the belt will not make noise when the vehicle is stated with the air conditioning on.

13
 
#28 ·
i need a good write up on adjusting my 4.2. no matter what i do to put tension on the alternator while trying to tighten the bolts, that sucker starts a little squeak each time i start the jeep. now that i have ac in it, it will surely squeak more.
 
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Discussion starter · #33 ·
Mambo_Dave said:
As one Floridian to another (and as a new Jeep owner), I want to thank Max for putting the pictures up and writing about it.
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Thank you, and you're welcome!

Whereabouts in Florida are you?

Max
 
#34 ·
After fighting a belt squeal on a 92 4.0L for about a month, I broke down and ordered a Dayco Laser Pulley Alignment tool. Turns out the Power Steering mount was bent and causing misalignment. I used common washers to shim out the mount and was able to eliminate the squeal.. after 2 shredded Dayco belts and 1 el cheapo belt. I think this 4.0 was either hit hard or was over tightened and bent. either way, just wanted to add this in when dealing with belt squeals.
 
Discussion starter · #35 ·
Luuca said:
After fighting a belt squeal on a 92 4.0L for about a month, I broke down and ordered a Dayco Laser Pulley Alignment tool. Turns out the Power Steering mount was bent and causing misalignment. I used common washers to shim out the mount and was able to eliminate the squeal.. after 2 shredded Dayco belts and 1 el cheapo belt. I think this 4.0 was either hit hard or was over tightened and bent. either way, just wanted to add this in when dealing with belt squeals.
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Great info.

I might have to get one of those Dayco laser tools for the shop, sounds like a good thing to have!

Max
 
#36 ·
Mean Max said:
Great info.

I might have to get one of those Dayco laser tools for the shop, sounds like a good thing to have!

Max
Click to expand...
You'll probably use it 10x as much as I will, but for $100, and to finally kill that squeal, it was worth it. It'll sit there, in it's case, until called upon to save my sanity again.
 
#37 ·
Serpentine Belt Slippage and Tensioner Pulley

Hi All. I have a 1998 TJ 4.0 with AC(although the AC isn't working). My serpentine belt slipped off, I replaced it, and the new one burned off. I checked all the pulleys by hand, and all were able to spin except the tensioner pulley. Figured the bearing was broken, replaced the pulley for a few dollars, tightened the tensioner with the long screw and thought I would be good to go. Without putting a piece of tape or marking the tensioner pulley, it is hard to see if it is in fact spinning, but I am still experiencing slippage of the belt, to the point where I do not think it is tight enough, and that must be causing the slip. I am not killing the main bolt in the pulley, but the pulley does not turn by hand when tightened without a belt on. What could the issue here be? Why would the pulley not turn by hand? Anyone experience this? All parts are new, and the bearing is good. Using Goodyear Gatorback Serpentine Belt, and it is definitely routed correctly. In the attached image, I am referring to the Idler Tensioner Pulley just below the power steering pulley. It is the type that has the center screw with the long screw on angle from the top.
 

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#40 ·
Walstr said:
Thanks for writeup effort. Please consider changing the title to YJ Serpentine ..... I was looking for XJ belt adj info.
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Welcome to the forum.:wave:

First of all, Mean Max hasn't been on here for several years. Second of all, it is in the YJ forum, so you have to "assume" that it's for a YJ. Third of all, you probably won't be back here anyway.
 
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