Hi there.. I just wanted to know will i have to change my alternator belt? Because i heard the pulley on the high output alternator is smaller so it moves fast nd since then you need a smaller belt then your orignal one? Thanks

I always recommend changing the belt 1/2" smaller. Generally the pulley's on HO alts are 2" and stock is around 2 1/2-3" in general. The smaller belt well ensure you have enough tension on the belt so it doesn't slip at load rpm/high load situations.

I had to get a larger belt. Whole thing was much larger than stock, which made the distance between the pulleys further appart than the OEM belt was made for.

Edited February 21, 201213 yr by watts09

Hmm because my alternator started making a LOUD screeching noise for about 10-15 seconds whenever i turn on my car.. It sounds lik a piece of $&@$ nd so embarassing! I have changed the belt quite a few time now, nd even made it tight as possible. May it be because the alternator has gone bad? Or maybe one of the bearings in it? Thanks

Just sound like belt squeal. I get a short squeak when i start my car as well. I only have a 3 groove belt, so that's my problem. Just make sure that the belt is tight and not worn.

I had to get a larger belt. Whole thing was much larger than stock, which made the distance between the pulleys further appart than the OEM belt was made for.

That's cause you didn't get a "direct" replacement. That is obviously a larger case. In which I could see it changing the geometry. But in general most people will need to shorten their belt.

Hmm well ive changed my belt 4-5 times by now bd couple times from different mechanics.. They all seem to not understand y it does not stop squeaking.... My belt even slipped away twice! But now last week i went to my mechanic nd he assured me its my alt.. So according to him i went back to my stock alt nd guess what? Not a single noise =/

HO alts usually have require more torque to turn the rotor then OEM. so its common for a worn belt to squeal a bit on start up. Most switch to a 1/2" smaller belt either Gates fleet belts or Gatorback's.

How old is the alt. Is it properly aligned? Do you have any belt shavings around the pulley? When is the last time you charged your batteries with an external charger?

The alt is only 6 months old nd my batteries are fairly new(3-4 months) nd even if my belt was brand new it wuld still make the noise.. I think i might just send in the alt to get it checked/fixed if any problem.. Do u think i shuld instal my new system a 15zcon/saz2500 as soon as i get it, or wait for the alternator to be fixed and put back in before installing in the system? Thanks!!

Are you sure the new alternator's pulley is lining up correctly? With a combination of symptoms like a new squealing belt, and that it has popped off, would point that you might need to shim to new alternator in order to line up the pulleys.

If you said the belt slipped off I would say your belt is to big. That is most likely your problem. Every alt manufacturer I have talked to has always said to change belts. And generally most people don't and end up with either low idle output or a squeal. Then think its a bad alternator.

FWIW.mine has a slight chirp when I start my vehicle as well. Especially when its cold out and the belt is still hard.

Belt noise on startup is usually an indicator of improper belt tension.

Also this can be caused by excessive battery discharge with the engine off, don't play your system with your car off.

Belt noise on startup is usually an indicator of improper belt tension.

Also this can be caused by excessive battery discharge with the engine off, don't play your system with your car off.

Improper as in too loose, or too tight?

Is the belt wrapped enough around the pulley?

EDIT double post, ssa still needs to work out a few bugs.

Edited February 22, 201213 yr by kirill007

My mechanic did the install, in pretty sure he did it properly unless hes the problem..

Might be....lol. But I would say the first time the belt slipped off I would have suggested trying a smaller belt if I were him. Also have you look at you tensioner to see how much its pre-loaded? There should be a little knotch in the casting and one on the arm. They should line up with each other. Another thing to check is alignment. Take a straight edge and place it flush with the other pullies and see if its out of line. You can look for belt dust too.

if the belt isn't touching enough of the pulley it will slip no matter how tight it is. have you tried a gates "green" belt or a goodyear gatorback? just some suggestions. good luck.

If the belt came off the pulley then you have one of 3 problems, belt too long, improperly tensioned or misaligned.

Keep in mind that this alternator uses a lot more power to turn than your OEM, and this power is taken from the engine via the accessory belt. As the output increases the horsepower required increases as well. You won't feel this spinning it off the car with no load, but once it's energized it's going to increase that load.

Check the belt alignment as mentioned above, if it is not aligned properly then steps will need to be taken to align the unit in the car. If it is aligned then you will need to properly tension a properly sized belt to make this function properly. At times you will get some belt slip from high output alternators due to poor belt wrap, poor tension or simply the lack of belt surface (narrow belt) when it is under load.

I installed a 300 amp mechman on my 2009 jeep.I put a new belt on but dont have any squeal issues.

I just installed a 370 on my Chevy avalanche the alternator is charging the battery but the odometer reads not charging could the belt be the problem? 

What year Avalanche ??