357i

iTrader: (4)

In the 2000 or so miles since I have been running my engine after the rebuild, I have thrown the serpentine belt off 2 times. The first time was after about 800 miles and the second time was at the dragstrip about 60 miles ago. I have never owned an LSx motor before this one. Both times I was able to recover the belt. There are no nicks or notches in it at all and it apears to be in perfect shape, no wear on the edges like a pulley miss alignment. I found that there are a few companys that sell a manual tensioner with a larger "lip" on the pulley that is suposed to solve this problem. The companys make this out to be a common problem with the gen 3/4 engines, but I have never heard about it on here. FYI, I do turn the engine 6500rpm.

http://store.katechengines.com/bille...sioner-p2.aspx

Thank you for your opinins

TooLateVTEC

iTrader: (2)

Well, im not sure about it being normal but its possible. Are the pulleys in any factory configuration? If not, than they may be out of alignment just enough to throw the belt and not noticeable to the naked eye.

Also, once a belt has been thrown off its basically no good and will get thrown off much easier the 2nd time.

LS6427

iTrader: (2)

YES.........its 100% normal.

If you are modded with just a medium amount of HP increase you will throw the belt when you wack the throttle. The factory (JUNK DESIGN) belt tensioner bounces too rapidly and the belt comes off. That Katech tensioner is what you need, it 100% soves the problem. When I got my 427ci put in I threw my belt about 8 times in one week until someone told me about the problem. I got the Katech and its been 8 years......with no tossed belt.

Thats another thing.........the factory tensioner allows the belt to bounce.....which in turn allows the belt to stretch over time. The Katech tensioner doesn't allow the belt to bounce one single bit, which resists or greatly reduces stretching.

I just changed my belt like a month ago....it was 8+ years old when I put my Katech tensioner on. Your belt will last until its starts to fall apart from age before it stretches.

With the factory tensioner that bounces...when you put a new belt on you can look at the indicator....its nice and tight. Then just a few months later you can see the indicator mark on the tensioner has moved already. Bouncing kills belts.

Get the Katech tensioner.

(Disclaimer...I'm sure there are people with modded engines that use their factory tensioners and DO NOT throw belts.......alot of guys just have that problem when they start modding. Katech solves it 100% for those of us that do lose belts.)


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357i

iTrader: (4)

The pulleys are all factory Fbody pulleys in the stock Fbody locations.

Thanks for the info

1madss

iTrader: (10)

How old is the stock tensioner? My H/C LS1 would start to fling the belt anytime I got over 5K rpm once the tensioner would get 40-50K miles on it. A new tensioner always fixed it for a while. I have a Katech now.

01ssreda4

iTrader: (96)

Buy a new tensioner from the auto parts store. Problem solved. The springs in them weaken with age and they don't function properly anymore.

jam01

no it is not normal at all, it is usually caused by misaligned and or bent or bad pulley's a bad or worn belt. while added hp will increase the chances of throwing a belt which is why gm made deep groove pulleys for higher hp engines way back when. this is also why the aftermarket makes parts and accessories, the katech tensioner should help you.

and contrary to some opinions the factory stuff is fine for most applications.

Jon@Texas-Speed

iTrader: (18)

Double check the alignment. If it looks good, throw a Katech tensioner on there and you will be set!

Jon