Serpentine Belt Help

[Danarch]

Looking for ideas. Have 2006 4.0 with an aftermarket York compressor for air. The PO removed the belt tensioner looks like it was replaced with a simple pulley. When I replaced water pump, fan clutch, flushed the coolant system etc. I replaced the belt. I replaced it with the same size belt. The new belt slips sometimes on startup, but that is it. Not sure if the belt slipping has anything to do with the Hayden HD fan clutch or not. The belt is tensioned by sliding the York compressor on its mounting bracket and is slid all the way out. I picked up the next smaller size belt and it is too small with the compressor slid all the way the other direction. The two sizes are 103.25” and 104”. Went to a couple different auto parts stores, called a specialty auto store and can’t find a belt between the two sizes. The alternator is below the York compressor. Anyone have any thoughts? Is there a place to special order a belt?

 

[Rickyd]

Sounds like it's time to modify the york mount or compare different brands of belt to see if one in the same size is actually manufactured smaller

 

[TJ Jim]

Try to find a bigger diameter idler pulley. Wouldn’t take much at all.

 

[sab]

Looking for ideas. Have 2006 4.0 with an aftermarket York compressor for air. The PO removed the belt tensioner looks like it was replaced with a simple pulley. When I replaced water pump, fan clutch, flushed the coolant system etc. I replaced the belt. I replaced it with the same size belt. The new belt slips sometimes on startup, but that is it. Not sure if the belt slipping has anything to do with the Hayden HD fan clutch or not. The belt is tensioned by sliding the York compressor on its mounting bracket and is slid all the way out. I picked up the next smaller size belt and it is too small with the compressor slid all the way the other direction. The two sizes are 103.25” and 104”. Went to a couple different auto parts stores, called a specialty auto store and can’t find a belt between the two sizes. The alternator is below the York compressor. Anyone have any thoughts?

Back when I installed my York, I did some research on belt lengths, including creating a spreadsheet of Gates part numbers and lengths using their web catalog. Here's the section from my spreadsheet containing belts in the range you are looking:

By the way, I don't know what the "Belt Product Number" means - no one seems to refer to that except the Gates web site. Everyone uses the "Belt Part Number."

What brand and part number were the two belts you have tried? Notice the sizes you have noted are not in that list above, but there are definitely other options through Gates. Perhaps the lengths you gave were measured in the parts store? I've also seen the wrong lengths listed for Gates belts. For instance, when I Google "Gates K061037", which is noted above to have an effective length of 103.74" on the Gates web site, I get two different lengths from product listings, and neither matches Gates' effective length:

Point being, when I was trying to hone in on the correct belt length, I ended up using the Gates numbers so that all belt sizes came from the same source (the Gates catalog). That way, I didn't get confused by wrong length information out there. It's very difficult to accurately measure a belt length due to their slight elasticity, and it seems there's a lot of bad length information out there.

Try to find a bigger diameter idler pulley. Wouldn’t take much at all.

This is a great suggestion, and I did some research here, too, when I installed my York. The instructions that came with my Off Road Only York kit listed two different idler pulley sizes available for the TJ belt system: a 70mm (Gates part number 38018) and a 76mm (Gates part number 38015). I scoured the Gates catalog and the internet for other sizes that were compatible with the TJ system and did not find any. Those are the only two sizes I could find. However, I was able to swap sizes idler size and belts to find one that fit best.

 

[Danarch]

Try to find a bigger diameter idler pulley. Wouldn’t take much at all.

Hadn’t thought of that idea.

 

[Danarch]

Back when I installed my York, I did some research on belt lengths, including creating a spreadsheet of Gates part numbers and lengths using their web catalog. Here's the section from my spreadsheet containing belts in the range you are looking:
View attachment 608503

By the way, I don't know what the "Belt Product Number" means - no one seems to refer to that except the Gates web site. Everyone uses the "Belt Part Number."

What brand and part number were the two belts you have tried? Notice the sizes you have noted are not in that list above, but there are definitely other options through Gates. Perhaps the lengths you gave were measured in the parts store? I've also seen the wrong lengths listed for Gates belts. For instance, when I Google "Gates K061037", which is noted above to have an effective length of 103.74" on the Gates web site, I get two different lengths from product listings, and neither matches Gates' effective length:
View attachment 608509

Point being, when I was trying to hone in on the correct belt length, I ended up using the Gates numbers so that all belt sizes came from the same source (the Gates catalog). That way, I didn't get confused by wrong length information out there. It's very difficult to accurately measure a belt length due to their slight elasticity, and it seems there's a lot of bad length information out there.


This is a great suggestion, and I did some research here, too, when I installed my York. The instructions that came with my Off Road Only York kit listed two different idler pulley sizes available for the TJ belt system: a 70mm (Gates part number 38018) and a 76mm (Gates part number 38015). I scoured the Gates catalog and the internet for other sizes that were compatible with the TJ system and did not find any. Those are the only two sizes I could find. However, I was able to swap sizes idler size and belts to find one that fit best.

I used the Gates K061037 and Gates K061045 both from Napa. I assume the pulley next to the water pump is the idler pulley? Actually looks like it is the plastic one further down by the alternator. I assume you ended up going with one of Gates pulleys you listed?

And Thank you, I think this may be a great option.

 

[sab]

I used the Gates K061037 and Gates K061045 both from Napa. I assume the pulley next to the water pump is the idler pulley? Actually looks like it is the plastic one further down by the alternator. I assume you ended up going with one of Gates pulleys you listed?

Yes, in my setup, there were two of those idler pulleys. I don't recall the stock sizes, but I do know I ended up going with two 70mm pulleys. By the way, both of those Gates pulleys are plastic and have a smooth (not grooved) surface to interface with the flat side of the belt.

 

[Danarch]

Yes, in my setup, there were two of those idler pulleys. I don't recall the stock sizes, but I do know I ended up going with two 70mm pulleys. By the way, both of those Gates pulleys are plastic and have a smooth (not grooved) surface to interface with the flat side of the belt.

Okay, thank you. Not sure if you can tell from the picture one is metal and one is plastic. Both are smooth.

 

[Danarch]

Yes, in my setup, there were two of those idler pulleys. I don't recall the stock sizes, but I do know I ended up going with two 70mm pulleys. By the way, both of those Gates pulleys are plastic and have a smooth (not grooved) surface to interface with the flat side of the belt.

Was able to go out at check, one is 70mm and one is 76mm. Decided to order one 70mm and one 76mm to see which works best. Thank you again for the ideas and part numbers etc.

 

[Danarch]

Thank you everyone for your help. I installed the 70mm pulley so I have two 70mm pulleys. The smaller belt is on and adjusted. I still have about 1/2-3/4” to slide the York if the belts slips. I don’t want it too tight so at a starting point to see what happens.

Thank you again!!

 

[Danarch]

Wanted to give an update. The two smaller pulleys are working well. It took a couple of adjustments but all seems to be working. I thought it was working, then the A/C was on and when I started the Jeep it slipped a little. Thank you all for the help.