Belt's for lunch!

[Shawn's 78]

Now twice in just as many months, I have thrown two brand new alternator belts. The first caused damage to the radiator house (cut it in half) and destroyed the clutch fan and the second (yesterday) I was much luckier. That one only split the belt. Though it wrapped itself around the flexfan/waterpump, I caught it before it did damage.

So why is this happening? :crazy The tension was correct so I'm leaning toward the alternator. The cooling fan and pully assembly have a slight variation to it (when you spin it, you can tell the fan moves in and out from the housing). Could this be my problem, or did i just get some bad belts (though new).

Vitals - 78 L48 manual. The alternator was replaced by the previous owner.

If I need to replace the alterantor, any recomendations? Maybe some chrome?
Thanks all!

 

[78SilvAnniv]

The cooling fan and pully assembly have a slight variation to it (when you spin it, you can tell the fan moves in and out from the housing).

I think you've got your problem. All of the pulleys should line up for a smooth flowing belt path, this variation you mention sounds like it is catching the belt and spitting it off, sometimes with damage.
Can you determine why that fan/pully assembly is wobbling? Perhaps that is what needs to be replaced.
Heidi

 

[427]

Not sure if this info will help ... But here goes anyway. The first Corvette I owned as a new '79 ... I threw my alternator belt a few times (also dislodging the PS belt) before I came up with a fix. Upon closer inspection, I noticed the bracket for the alt was flexing a lot ... Especially under heavy throttle. What I eventually did was weld two brackets together to limit the flex ... That cured my problem.

Hope that helpz,
Jack

 

[cruzer99]

There is an outside chance that when the clutch fan kicks in it puts to much drag on the belt. It is unlikly but might be worth checking.
9 times out of 10 pully alignment is the culprit.
Just a thought.........

 

[Bob Chadwick]

Bad bearings on the water pump?

 

[Shawn's 78]

Thanks for the ideas. The mounting bracket does vibrate a bit, but at this point I'm sure it is the alternator. Since they are kinda cheap, i'll order a new one. Then for sure I will be able to eliminate all the possibilities.
For know, i'll install a new belt and not drive to far from home.

 

[C3forME]

I agree with Bob, it sounds to me like a bad water pump bearing. If you notice, the alternator belt rides very close to the power steering pump housing to start out with. If the water pump bearing goes bad and the shaft wobbles at all, there's a good chance it is hitting the power steering pump housing and shearing the belt. Also check to see if there's any marks on the p/s housing to confirm your suspicions, and check to see if the belt guide bracket that goes in there is in place as well.

 

[Shawn's 78]

I'll check out the water pump here this coming week. Been busy planning a block party (July 4th) for 500 of my neighbors :crazy.

Question - Would the water pump leak if the bearings are bad? or would it go all at once?

Thanks again!

 

[Bob Chadwick]

Can leak if the bearings are going bad but doesn't have to in the beginning.

 

[LIRacer]

Your harmonic balancer may be spun. My LT-1 threw belts like baseballs. Spent months working on it until I removed the distributor and then found I couldnt get the timing mark (which is on the harmonic balancer) to TDC when the rotor was pointing to the #1 cylinder.

 

[Shawn's 78]

I replaced my HB after i threw my first belt. The HB was shot!

I received my alternator from Summit yesterday. I bolted it on (chrome looks great) and what do you know, no excess vibration. A closer look into the old alternator (Delco), and it has some play when I move it around? Could that be the cause?? Don't know, but we'll soon find out. Also, there were no belt scrapes on the p/s housing. I've got about 3/4" clearance.

Thanks all for the input.
Shawn
Sunny in Seattle and I'm the envoy of the neighbors. Except for the guy down the block who just bought a 2003! Nice Vette!!