Shredded serpentine belt

K-rover

Well-known member
Jan 15, 2010
2,100
43
Raleigh, NC
Just got home from a 900 mile trip through the Appalachian mountains. Truck ran great except for a small pinhole leak in the coolant return line. Luckily it happened right at the radiator so I had enough slack to cut the pinhole out and reconnect the hose.

This morning Im going over the truck to start getting it ready for the next trip a few weeks from now. I pop the hood and notice the serpentine belt is shredded and only about half of it is left! Pieces of belt all over the engine. We were lucky to make it home!
Now to find out what caused it.. I just started the truck to look for seized pulleys, but I couldn't see anything obvious.. Turned the AC on to see if that made a difference, but nothing out of the ordinary. I do hear a slight whine with the Ac on, buy thats it..
I have a new waterpump on the way along with valve cover gaskets I planned on doing before the next trip. Any suggestions as to what could cause a belt to shred like that?

I dont remember the last time I replaced the belt. Its been a while..so maybe it was old? Although I never really noticed any cracks on my pre trip check..
 

Flyfish

Well-known member
Oct 29, 2004
1,075
87
49
St. Louis
I’ve seen the AC compressor cause that. Maybe it’s getting a little sticky.

Otherwise, if there’s no play or defects in any of the pulleys, maybe one of the ancillaries is loose and out of alignment.
 
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sdtim

Active member
Feb 21, 2021
27
10
Oceanside, CA
I once installed my power steering pump pulley backwards and it destroyed my belt. It was offset just enough to be misaligned, but not visually obvious.
 

K-rover

Well-known member
Jan 15, 2010
2,100
43
Raleigh, NC
Found one of the idler pulleys had some play in it. So I ordered a new one. Other than that everything looks normal.

Is there a way to tell if the AC pulley/ compressor is the issue? It spins freely.
 

Flyfish

Well-known member
Oct 29, 2004
1,075
87
49
St. Louis
Is there a way to tell if the AC pulley/ compressor is the issue? It spins freely
You said there was a whine with the AC turned on. Maybe when you turn the AC on, the pulley isn’t spinning as it should when the clutch is engaging. Probably worth a look.
 

JohnnoK

Well-known member
Mar 19, 2017
180
17
Cape Town, South Africa
My Disco Td5 shredded 2 belts in quick succession and I could never get to the bottom of it.
One was a pattern part and I put it down to crappy quality, the second was genuine LR.

Toothed timing belts should go back on the same way, according to Gates....
 

Flyfish

Well-known member
Oct 29, 2004
1,075
87
49
St. Louis
My Disco Td5 shredded 2 belts in quick succession and I could never get to the bottom of it.
One was a pattern part and I put it down to crappy quality, the second was genuine LR.

Toothed timing belts should go back on the same way, according to Gates....
It’s a serpentine so belt direction shouldn’t mater. Just has to be routed correctly.
 

ahron

Member
Jan 4, 2018
12
1
GA
Found one of the idler pulleys had some play in it. So I ordered a new one. Other than that everything looks normal.

Is there a way to tell if the AC pulley/ compressor is the issue? It spins freely.
We'll be checking this Disco project soon with the same issue as per the current owner. It has idling issues as well. Gonna need to finish installing the bumper and winch on the Wrangler this weekend before we can take a closer look. We'll start with the idler pulley.
 

simondewing

Well-known member
Feb 10, 2020
54
11
Texas
Bought one of mine as a craigslist bargain, non running with a shredded belt and casting the tensioner bolts to fractured and tensioner lying loose. Replaced the tensioner and associated bracket and all seemed fine with a new belt

A few hundred miles later the new belt shredded and the power steering pump appeared to be locked up.
Replaced the power steering pump with a spare, flushed the system replaced the belt and its been fine since.

When I first replaced everything it seemed fine but as it seized up again shortly after it is likely the initial point of failure.
Pulled the old pump apart and found some debris and grit in and around the rotor.
I am guessing that some dirty power steering fluid was added at some point which caused the initial failure and the force was enough to fracture the cast bracket.

Probably worth checking yours and maybe flushing the steering system if you cant find another obvious fault with the ac clutch/compressor or idler pulleys.

Simon
 

K-rover

Well-known member
Jan 15, 2010
2,100
43
Raleigh, NC
Well one of my mechanic friends told me its more than likely the tensioner going bad.. probably right. I dont think it's ever been replaced. So I just ordered one and already replaced the other idler pulley.
 
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ahron

Member
Jan 4, 2018
12
1
GA
Well one of my mechanic friends told me its more than likely the tensioner going bad.. probably right. I dont think it's ever been replaced. So I just ordered one and already replaced the other idler pulley.
Hope the new tensioner will give a good difference.
 

K-rover

Well-known member
Jan 15, 2010
2,100
43
Raleigh, NC
Got the new tensioner in, along with a new idler pulley. A new water pump, inline tstat, fan and fan clutch and valve cover gaskets. Started it up and the truck immediately revved up without me touching the pedal.
Looks like my throttle linkage cable is stuck or not working correctly. I can pull the linkage down by hand and the idle comes down, but it will get stuck again if I touch the pedal.

The new belt seems to be riding fine, but I am hearing a faint thumping noise that sounds rotational with revs, but cant seem to isolate it. Cant hear it at idle.

I need to get the throttle situation figured out so I can take it for a test drive and see.

Any suggestions on what to look for or adjust with the throttle?
 

JohnB

Well-known member
Oct 18, 2007
2,282
8
Oregon
My ac clutch bearing caused issues like this but at idle mostly. Least that's when it over heated in the taco bell line. At first just thought my belt was old and shreaded.

Had spare idler pulleys and such that tried first and thought was fixed until the ac bearing grinded to a hault.

Luckily the ac clutch bearing was pretty simple to replace.
 
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jastutte

Well-known member
Nov 10, 2009
346
32
My ac clutch bearing caused issues like this but at idle mostly. Least that's when it over heated in the taco bell line. At first just thought my belt was old and shreaded.

Had spare idler pulleys and such that tried first and thought was fixed until the ac bearing grinded to a hault.

Luckily the ac clutch bearing was pretty simple to replace.


is there a write up on how to replace the A/C compressor clutch bearing?

the bearing on my 2001 Discovery starts screaming everytime the A/C is turned on.