serpentine belt comes off

brown bear

como estan beeches!!
Mar 31, 2009
199
0
0
Durango CO
so i notice that almost every time the my truck hits the 100's mph the serpentine belt comes off i was wordering why is that and also if theres anything i can do to avoid that (besides slowing down) :hug: its just getting expensive everytime have to spent about 50 bucks on a new belt from napa thank you
 

brown bear

como estan beeches!!
Mar 31, 2009
199
0
0
Durango CO
gotcha ill do that hopefully wont get this problem again or for at least for another 100k milles lol thank you guys
 

Vrabel

TOYAHOLIC
May 22, 2008
3,434
0
0
56
Hewitt, NJ
X2 on tensioner, get one from dealer. I remember when I got mine,it was actually a few bucks cheaper than parts store. imagine that.
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,324
1,611
113
Mid Michigan
X5 its the tensioner. I lost my belt at the end of a run last year. Its no fun losing brakes/steering at 90mph. :eek: Thank God I carried a spare belt, other wise I wouldnt have gotten home. Id replace the two idler pulleys at the same time. Good insurance.
 

dmaxvaz

wannabe puller
Nov 22, 2006
1,132
0
0
46
METRO DETROIT
I am at my whits end with my truck too!:( i have replaced the idler pulleys, tensioner and tensioner pulley. My belt is getting torn up too often, the belt jumps over after a hard run and over 4000 rpm 100+mph. My buddy says he had the same problem and he remedied it with a better bearing, i will find out soon and let you know whats happening
 

MaxPowerLB7

Amateur
Nov 8, 2007
623
0
16
39
Spanish Fork, UT
I've been in the same situation. Replaced tensioner first(with aftermarket tensioner) didn't fix it. Replaced both idlers, didn't fix it. Replaced alternator, cause the bearings felt like the were starting to bind, didn't fix it. Like seven belts later I purchased another tensioner from the dealership(knowing that it wouldn't fix the problem) and have never had a problem since!
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,324
1,611
113
Mid Michigan
Vaz, use a straightedge and check your pulley alignment, esp the powersteering pulley. Thats probably whats going on in your case.
 

steakman

Diesel Nut...
Aug 31, 2009
69
0
0
Barrie, Ontario
at ~144,000 miles...I'm thinking it's time to do mine. May as well do the tensioners at the same time. Given the info here...I will for sure use OEM parts.
thanx,

Theo
 
Last edited:

dmaxvaz

wannabe puller
Nov 22, 2006
1,132
0
0
46
METRO DETROIT
i got the better bearing pressed into my factory pulley, so far so good for like 3 weeks now, no more belt jumping:happy2:
 

Bobza57

New member
Dec 22, 2009
1
0
0
Carmel, NY
Is the idler pulley on the tensioner for My 03 2500 HD Duramax a separate part??:(....The dealer says I have to purchase a new tensioner with pulley for $107.51
 

DAVe3283

Heavy & Slow
Sep 3, 2009
3,682
236
63
Boise, ID, USA
I couldn't get just the pulley on the tensioner from the dealer. I took the pulley off and brought it into a couple parts houses, and one of them was able to find a match (I think it was Napa?). Cost me like $20 instead of 100+, and has been working for over 10k miles.
 
  • Like
Reactions: 08lmm72mm

onebadduramax

One Bad Duramax
Jul 28, 2009
30
0
0
mine keeps doing it replaced the pulleys alt belt 3 times and has a new idler pulley this happens when i really step on it

plus if i put a factory belt on it will quick like crazy and if i put the gatorback on no noise
 
Last edited:

Baking83

New member
Apr 17, 2022
21
4
3
I can’t keep my belt on.
Built 7.1 stroker Lml dual fuel
Wagler tensioner tight as s***