• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-

SERPENTINE BELTS KEEP SHREDDING

  • Thread starter Thread starter paddyrk
  • Start date Start date Oct 22, 2018
  • Tags Tags
    pulley serpentine shredding tearing v eblt

paddyrk

Member
Jun 7, 2018
71
5
18
Dublin, OH
Oct 22, 2018
#1
  • Oct 22, 2018
  • #1
Hi, I have a 1991 347 stroker that puts down 331 hp and 370 ft-lbs of torque at the wheels, and after I had it dynoed I keep shredding serpentine belts. I did an A/C delete about a week before the dyno day and it seemed to run fine, but the computer was so messed up that it hardly made any power anyway. I took it to cars and coffee in Columbus (a 20 minute highway drive) and ran in hard on the way there, and then when I did the same thing on my way home, about 10 minutes in, while just driving normally, my father who was behind me said he saw the belt fly off, my battery light came on, then my coolant temp shot way up. We went back and collected the belt and it was only half of the belt. I replaced it, went home, then took it out the next day. It was a Sunday morning so of course I pulled once of twice, and it seemed fine. I popped the hood that night and found that I was missing two of the ribs on the belt.

Would this be a pulley problem? Or do I need a heavy duty belt? Any would help would be appreciated. Thanks.
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,194
17,889
224
Massachusetts
Oct 22, 2018
#2
  • Oct 22, 2018
  • #2
Usually it's an alignment issue which can cause shredding of the belt. Did you install an A/C delete pulley, or the Ford M-8511-A50 kit that moves the PS pulley up? I'm assuming the pulley?

With the new belt on, can you verify alignment? Since the issue started after the a/c delete, I would imagine there's a slighty offset from either the A/C delete pulley to the PS pump, or to the tensioner.
 

paddyrk

Member
Jun 7, 2018
71
5
18
Dublin, OH
Oct 22, 2018
#3
  • Oct 22, 2018
  • #3
Mustang5L5 said:
Usually it's an alignment issue which can cause shredding of the belt. Did you install an A/C delete pulley, or the Ford M-8511-A50 kit that moves the PS pulley up? I'm assuming the pulley?

With the new belt on, can you verify alignment? Since the issue started after the a/c delete, I would imagine there's a slighty offset from either the A/C delete pulley to the PS pump, or to the tensioner.
Click to expand...
I installed a delete pulley from LMR, I will check the alignment, I assume everything should be straight up and down?
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,194
17,889
224
Massachusetts
Oct 22, 2018
#4
  • Oct 22, 2018
  • #4
paddyrk said:
I installed a delete pulley from LMR, I will check the alignment, I assume everything should be straight up and down?
Click to expand...

Correct. I'm guessing the pulley and PS pulley may not be fully aligned.
 

paddyrk

Member
Jun 7, 2018
71
5
18
Dublin, OH
Oct 22, 2018
#5
  • Oct 22, 2018
  • #5
Mustang5L5 said:
Correct. I'm guessing the pulley and PS pulley may not be fully aligned.
Click to expand...
If one was further towards the front of the car than the other or on a slight angle, how would align it? Would I just make sure all the bolts were tightened?
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,194
17,889
224
Massachusetts
Oct 22, 2018
#6
  • Oct 22, 2018
  • #6
really depends on which pulley is off. If it is the A/C delete pulley, may have to shim or shave part of it down to match the offset of the other pullies.
 

89ripper

Founding Member
Jun 3, 2002
926
308
103
Rockford, Illinois
Oct 22, 2018
#7
  • Oct 22, 2018
  • #7
I would take a level and measure that delete pulley against another one to get an idea. Might be worth a look. Maybe the delete pulley defective
 

General karthief

wonder how much it would cost to ship you a pair
5 Year Member
Aug 25, 2016
27,856
10,533
203
polk county florida
Oct 22, 2018
#8
  • Oct 22, 2018
  • #8
Tell tail sign is if the front part of the belt is shredded pulley is too far back, if the back of the belt is shredded then it's to far forward, gives you an idea of what to look for when checking the alignment.
 

90sickfox

Wasn't a pretty sight...and I've got big hands
SN Certified Technician
Mar 2, 2015
6,945
5,816
213
Oct 22, 2018
#9
  • Oct 22, 2018
  • #9
Is your idler pulley smooth...or does it have shoulders like this ?....



Or smooth like this....



The pulley should have shoulders like the original factory metal one. Under stress the tensioner will flex and cause the belt to throw... or shred.

The only local store that sells the correct one is AZ.... they have been selling people incorrect pulleys for 20 years and won't fix it.

Here's what the original looks like...top pic....



It's also highly likely that you have an alignment issue... but change the tensioner pulley if you have the smooth one also.
 

Boostedpimp

20+ Year Stangneter
May 8, 2003
1,451
493
154
NJ
Oct 22, 2018
#10
  • Oct 22, 2018
  • #10
If it were me, I'd return that delete pulley back to LMR and just modify the stock tensoner and run a shorter belt.

I've done it many times back in the day on cars without any issues

Here's an old write up someone did although I don't remember drilling anything. Just taking the spring out and reversing it if I remember right

http://www.angelfire.com/ns/PurgingPony/Belttensioner.html
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,194
17,889
224
Massachusetts
Oct 22, 2018
#11
  • Oct 22, 2018
  • #11
Or run the LMR/Ford kit that relocates the pS pump higher
 

paddyrk

Member
Jun 7, 2018
71
5
18
Dublin, OH
Oct 22, 2018
#12
  • Oct 22, 2018
  • #12
I used washer between the pulley plate and the mounting plate and that was able to move it backwards enough to not have it rub against the front of the delete pulley. Now I’m off to terrorize super cars around the city.
 
Reactions: General karthief, Davedacarpainter and 90sickfox
You must log in or register to reply here.

Similar threads

Belt Tensioner Question...
  • robw13
  • Mar 10, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
3
Views
238
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Mar 10, 2025
gkomo
D
Engine Serpentine belt squeal after reinstall?
  • dqureshi06
  • Oct 30, 2024
  • Fox 5.0 Mustang Tech
Replies
15
Views
825
Fox 5.0 Mustang Tech Nov 1, 2024
Noobz347
Engine Coolant boiling in hose?
  • Teen'93stang5.0
  • Jun 3, 2026
  • Fox 5.0 Mustang Tech
Replies
7
Views
121
Fox 5.0 Mustang Tech Jun 8, 2026
Mustang5L5
L
95 gt engine vibration
  • lenzgt
  • May 11, 2026
  • 1994 - 1995 Specific Tech
Replies
6
Views
146
1994 - 1995 Specific Tech May 26, 2026
lenzgt
L
Y
Engine 1994 Ford Mustang Gt Rod Knock/Stuck Lifter
  • yaboity
  • Jun 7, 2025
  • 1994 - 1995 Specific Tech
Replies
2
Views
256
1994 - 1995 Specific Tech Jun 8, 2025
AeroCoupe
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?