Jeep Wrangler Forum banner
  • Hey everyone! Enter your ride HERE to be a part of JUNE's Ride of the Month Challenge!
1 - 9 of 9 Posts

·
Registered
Joined
·
20 Posts
Discussion Starter · #1 ·
hi ,

I have 2006 TJ with 4.0 stroker engine and i have a problem with my Idler Pulley.

The last mount the Idler Pulley bolt was snapped and half of the bolt was stuck inside the engine head it's was a nightmare to get it out, we weld a nut to the edge of the bolt and somehow its work out for us after few tries then i replaced the broken bolt with stronger grade 8 bolt and today the same thing happen again! now the bolt is stuck again and i won't sure the welding trick will work out for me again and i don't know why this thing keep breaking out! anyone have an idea why this keep happening?


 

·
Registered
Joined
·
1,269 Posts
That doesn't make sense, how long did the second bolt last? It's virtually the same as the tensioner pulley mounting.
How tight is your belt? too loose may cause excess vibrations and belt squealing, to tight causes stress on everything but usually takes a bearing out of something.

BTW, harder also make it more brittle, but still shouldn't break. I'd stick with a stock Jeep bolt till you figure it out.
 

·
Registered
Joined
·
20 Posts
Discussion Starter · #4 ·
I didn't replace the pully last time, this time I will replace it with a new one with a new bearing.

the last one held for like 3 weeks and not many miles cuz its not my daily right now.
I remember I tried to find the right torque spec for this bolt and i didn't so i torque it to like 30nm I think, maybe this is the problem?

another thing that crosses my mind is the tensioner pulley can this tensioner can go wrong and snap the idler bolt by pulling the belt too much? I notice my engine when i open the throttle make the tensioner move pretty hard.

thank you guys for the comments!
 

·
Registered
Joined
·
1,979 Posts
Besides making sure that the idler pulley and tensioner pulley are both good, I'd also make sure that the belt you are using is the correct length for the options the Jeep has. If you see the tensioner moving a long way, then the belt you have may be too long for the configuration of your Jeep. This can cause the belt to jump off of the idler pulley and get wedged behind it, which could break the bolt.
 

·
Registered
Joined
·
20 Posts
Discussion Starter · #7 ·
Put a nut on it and weld it from inside the nut, I've seen this work well before
That's exactly what I did last time, but i cut the nut to half and then i weld it to a shim to protect the cylinder head and then i weld the shim and the half nut to the remaining stuck bolt and its work for me again today but just barely the shim has melted and almost weld itself to the cylinder head ..

i also replaced the pulley to a new CROWN one, it came with a grade 3 bolt but the bolt was too long I think its because I am using 0630 cylinder head with my stroker engine so i used an 8-grade shorter bolt again .


Besides making sure that the idler pulley and tensioner pulley are both good, I'd also make sure that the belt you are using is the correct length for the options the Jeep has. If you see the tensioner moving a long way, then the belt you have may be too long for the configuration of your Jeep. This can cause the belt to jump off of the idler pulley and get wedged behind it, which could break the bolt.

the belt is going under the idler pulley and push it upwards when its slip the pulley there isn't any tension anymore how it can break the pulley?
I thought I would change it to a new one but I'm worried that new will make more tension on the pulley.

the belt isn't new and i now that it's the right belt cuz its was working for me for awhile .. i can't figure out what has been changed that make my engine a pulley bolt snapper...
to be safe i will change the belt too.

how can i chack out my tensioner pulley? it's moving when the engine working and the marked arrow is between 1 and 2 marks


another thing that's i thinking to do is something like this


this mount on the alternator mount and the bolt will press the pulley down and helps it handle the force upwards from the belt
that's sound like a good idea ?
 

·
Registered
Joined
·
1,979 Posts
I just looked at the markings on my tensioner and while the engine is off, it sits right at the II mark.
The reason for my comment is that last spring I changed the serpentine belt on my GMC Suburban plow rig as a preventive maintenance item. I don't drive it much in the summer, but I started it and drove it several times over the summer. The first big snow we had this winter I plowed with it for a few hours. I heard the belt start slipping and headed home. I got within a block of my house and the belt jumped off the idler pulley and got wedged behind it. This destroyed the bearings in my idler pulley ( and I assume it could have easily snapped the bolt off). It also shredded the belt. It turned out that I bought the wrong belt as my car had A/C but didn't have an air pump on it. The belt was something like an inch too long, but this made a huge difference. I noticed the correct belt was much harder to install as you really had to crank the tensioner out of the way, with significant force, to get it installed, where the belt that was too long still required the tensioner to be pulled out of the way, but no where near as far. I can't really imagine any other reason the idler pulley would snap the bolt, unless maybe the bearings in the idler pulley or tensioner pulley were bad and it seized while the engine was running.

Whatever the cause, there is no reason you should have to engineer a new design as your issue is not normal. There is a simple reason this has happened twice. Check for correct belt, and make sure the tensioner and idler pulleys both spin with no clicking, seized up bearings inside.
 

·
Registered
Joined
·
20 Posts
Discussion Starter · #9 ·
I just looked at the markings on my tensioner and while the engine is off, it sits right at the II mark.
The reason for my comment is that last spring I changed the serpentine belt on my GMC Suburban plow rig as a preventive maintenance item. I don't drive it much in the summer, but I started it and drove it several times over the summer. The first big snow we had this winter I plowed with it for a few hours. I heard the belt start slipping and headed home. I got within a block of my house and the belt jumped off the idler pulley and got wedged behind it. This destroyed the bearings in my idler pulley ( and I assume it could have easily snapped the bolt off). It also shredded the belt. It turned out that I bought the wrong belt as my car had A/C but didn't have an air pump on it. The belt was something like an inch too long, but this made a huge difference. I noticed the correct belt was much harder to install as you really had to crank the tensioner out of the way, with significant force, to get it installed, where the belt that was too long still required the tensioner to be pulled out of the way, but no where near as far. I can't really imagine any other reason the idler pulley would snap the bolt, unless maybe the bearings in the idler pulley or tensioner pulley were bad and it seized while the engine was running.

Whatever the cause, there is no reason you should have to engineer a new design as your issue is not normal. There is a simple reason this has happened twice. Check for correct belt, and make sure the tensioner and idler pulleys both spin with no clicking, seized up bearings inside.

thanks again for all the comments !

tomorrow i going to buy and replace my Serpentine Belt , what are the right length for 2006 wrangler TJ with AC ?

edit :
figure out this one will fit - its 88" - That's the right size ?
https://www.quadratec.com/products/51213_20.htm
 
1 - 9 of 9 Posts
Top