# walking/throwing belts! whats going on?



## motoristx (Apr 27, 2010)

hey guys, i've been beating myself up trying to find the problem, or cure for the belt issue i've been having.

first of all, it an 05 GTO, with a few mods on the pulley system. I have an underdrive crank, and i'm looking for an overdrive alt. when i get on it a bit, i have to pop my hood just to make sure it's still on streight; it likes to walk over a groove or 2 on the tensioner pulley. this in turn pulls it slightly off the water pump pully, and gets it out of line on the power steering a groove or 2.

with this beeing said, i have bought a new tensioner, and a new belt (el cheap-o till i get this fixed). *edit* there are 3 indicators on the tensioner, i'm lined up at the tightest one.*edit* i have considered getting a tensioner pulley machined with higher edges on it, as to "guide" the belt a little better, but i think this might just mask some other problem. 

also i have checked the water pump (nice and solid), the power steering has no side to side motion. alt is good, almost looks new, free spins nice and easy. the idler is slightly loose, but i can't see that cuasing anything since it don't jump or walk off the crank UD pulley.

what do you think?


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## 87GN06GTO07IRL (Aug 10, 2009)

If your belt walks your pulleys are not aligned. I take it this started once you installed the ud? I'd start there.


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## motoristx (Apr 27, 2010)

hate to say it, but I just bought it like this. it only does it when I'm getting heavy into the throttle, and it's only "every-once-in-a-while". i have eye balled it, and it looks good, but then i'm half blind... it hasn't "pollished" one side of the belt either, so i'm thinking it is just getting to where the spring is not taking up the slack or something. this is why i'm going with the idea that if i got a pulley with higher "guides" it might solve it. or just going with a manual tensioner, but I don't want to that route yet.


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## GM4life (Mar 18, 2007)

Your crank pulley may not be fully seated. The crank bolt suppose to be tighted to 240ft-lbs. I would try to see if it has the correct torque on it before anything else. Surpintiene belts are not like the old V-belts where they can be slightly off, and still work fine. Some brands of UD pullies have short retention walls, I think one company claims they have tall ones.


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## jetstang (Nov 5, 2008)

My Vette was eating AC belts, the idler pulleys were shot.
I had a plymouth voyager that was throwing belts, I turned the belt around and it stayed on forever, as if the belt is directional, but it worked.


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## Rukee (Feb 8, 2007)

The bearings should be tight in the idler pulley, if it moves around replace the bearing or the whole pulley.


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## motoristx (Apr 27, 2010)

ok i resolved my problem.

i retained my stock belt tensioner, put a custom Tensioner pulley on it with bigger/taller edges, it cost 40 bucks on ebay. Bam! no more throwing belts! i'll see about posting a pic of it sooner or later.


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## motoristx (Apr 27, 2010)

Ebay link here to pulley i bought


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## dquack (Oct 28, 2009)

I was driving heavy down the autobahn today and noticed a slight whining when I hit the off ramp. I pulled it home slowly and noticed the belt had jumped one rib to the outside. I have had the car for 6,000 miles and this has never happened. The outside outer edge of the belt has a slight raise to it now. I think it is going to walk again. I am thinking of replacing the belt any other ideas while I have the belt off?


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## vxssls1 (Sep 9, 2006)

ive used the gates high walled pulley ..it worked treat
Gates 38009 Auto Part | Car Replacement Part


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## motoristx (Apr 27, 2010)

ya that aluminum tensioner pulley worked great, it's never come off again. 

see my belt was coming off with new belts and new oem tentioner pulleys. Nothing would stop it from walking off till i found this pulley with higher edges on it. it was only 40 bucks before shipping, and i didn't want to put a manual tensioner on it.

like i said, not an issue, even with an under drive Crank pulley, and it looks kinda cool too, while keeping the stock look.


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## dquack (Oct 28, 2009)

I could only find 38008 DRIVEALIGN IDLER PULLEY made out of thermoplastic. I found the 38009 pulley, but the Gates' website said it wasn't for the GTO. I am stuck in Germany so real hard to run to the autozone/NAPA and buy the parts I need. Thanks.


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## motoristx (Apr 27, 2010)

buy this one, LS1 LS2 LS3 LSX F-body & GTO Billet Tensioner Pulley!: eBay Motors (item 110510983682 end time Jun-21-10 11:21:41 PDT), it's the one i got and it stoped the walking problem for me. i was hesatant to buy it at first, but the guy told me if it didn't stop the problem i could send it back for a refund less the shipping costs. it works for the LS1 and LS2 engine. 

as for the other pulleys, if it doesn't say LS1 or LS2, i wouln't even try it. as for the tensioner, if it still jumps off the pulley with the high walls, you'll more then liky have to buy the manual tensioner type. that kit is a direct bolt on replacement, but it's about $100 to $150 depening on who you get it from

*edit* as for being over seas, i know how you feel, i was in Okinawa, on Kadena AB for a while. i understand how frustrating it can be buying american parts, or in our case, Aussy parts would even be harder to get locally!


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## fattirewilly (May 26, 2006)

My car threw the S-belt while autocrossing. It busted one of the 6 ribs, but I trimmed off the 6th rib, put the 5 rib belt back on and limped home, keeping the rpms under 2,500.

My belts/pulleys are stock. I thought it was a freak incident, maybe not? I haven't had it back autocrossing yet, but I now keep an extra belt around.


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## motoristx (Apr 27, 2010)

mine did the same thing, one of the nylon cords beat the heck out of my under-hood insulation, but this was with my stock tensionor pulley. what happened is it walked off the pulley by one rib, and the edge of the pulley effectively trimmed that rib right off the belt. be sure to keep a 13mm or cresant wrench with you so you can put the belt on if you need to!


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## GM4life (Mar 18, 2007)

I keep a spare belt, Harbor Freight breaker bar with a socket in my trunk. I've done this every since the supercharger been on.


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## dquack (Oct 28, 2009)

motoristx said:


> Ebay link here to pulley i bought


I found that one on Ebay and when I e-mailed some of the previous buyers they said "Does'nt fit well rubs up against the pulley bracket".



vxssls1 said:


> ive used the gates high walled pulley ..it worked treat
> Gates 38009 Auto Part | Car Replacement Part


That looks like the normal pulley, you sure that is the high walled pulley?


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## motoristx (Apr 27, 2010)

it rubbed VERY SLIGHTLY. but ya it rubbed a little on mine, but i'm still using it. i just took a file to it, but that would be your cal if you wanted to do that. *edit* i took a file to the tenstioner, not the pulley. (just to clarify)


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## vxssls1 (Sep 9, 2006)

dquack said:


> That looks like the normal pulley, you sure that is the high walled pulley?


its not a big side wall but enough to stop the belt from coming off
I fitted one on a customers 403 TT that would throw the belt as soon as you gave it a big rev fitted this and it was all good


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