I'm running into problems with the serpentine belt. It jumps and rips them up. I've checked the pulleys and all seem to be okay with no damage and within spec size, except for the recently replaced autozone alternator because I am not sure what is the stock pulley size. The belt tensioner is almost fully extended leaving no more room for tension. The belts replaced were from autozone and I tried both brands Dayco and Duralast and recently a Napa (Gates) belt. I did try another used belt tensioner I have and had the same problem. I don't think its the tensioner because they are almost fully extended. Smog pump is still installed.

The only thing left for me to check right now before searching for a smaller size belt, is the pulley size for the alternator. Can someone help with this before I start pulling out the little bit of hair I have on my head.

 

GM # 10496580 is the factory pulley and there are dimensions posted for that part number numerous places on the Internet.

I don't have one to measure but I've seen 52mm mentioned most frequently for it. Here's one link and you can search more if you'd like:

http://store.alternatorparts.com/sea...?find=10496580

Diameter is at the V and not the OD of the pulley. I had a fellow drive about 60 miles to return a correct one because he didn't know how to measure and was to foolish to call. Not this particular pulley but something similar.

 

Thanks. I had searched the web before and did not find anything.

Just measured mine with two different dial calipers and it shows 51.3 mm Not much, but could that be the problem?

 

While I was on vacation last week with the vette the alternator died and I replaced it with one from Advance. I was having a turn signal problem and dropped it off at a shop. The guy at the shop noticed that the alternator pulley sat too far in and added 2 shims to make it line up with the rest of the system. He said it would have shredded the belt if left the way it was.

 

The offset dimensions are included in the link I posted so you could check that and if it were different from the link then you could have similar problems as was mentioned in the post above me. The fan could also create the alignment issue.

Here's a correct fan but there's no height mentioned. How long ago did you return the core for the alternator?

http://store.alternatorparts.com/251...nator-fan.aspx

 

The alternator was changed a little over three months ago. Shortly after I had my first belt failure. Not a good feeling going over a curved causeway going about 65 and you lose your power steering. Belt shredded to pieces on that date. Replaced belt and that one lasted about a month. Did a trip from central Florida to Miami and back with no problem. A week ago second belt goes, new one installed, lasted a day. Went with a Napa belt and of course gone.

This is not a daily driver, just for fun or a quick errand. I did not want to buy anymore belts right now so I trimmed the damaged strip area. In essence one line and did some testing. My findings were that at start up is when the belt jumps. I can see that the belt rolls torward the engine side of the A/C pulley. Thats when it starts to destruct. Checked the A/C pump and pulley and it's all within specs and no play or damage. Tried two tensioner pulleys, no change. Now I do notice that the tensioner is almost fully extended, leaving me to believe that the belt is to long.

Now backing up a little more. I did rebuild this engine recently. Heads were shaved a little (74cc) now and very thin .015 felpro head gaskets were used. I dont think that would make much of a difference but just throwing it out there just in case.

All help is greatly appreciated.

 

Forgot to mention that the alternator seems to line up well.

 

A few millimeters in diameter are not causing this. I have an under-drive crank pulley and an over-drive alt pulley with a "not stock for the car" belt size. You have an alignment issue. You mentioned an engine rebuild. Are all the accessory drive support brackets and braces on? EVERY one of them?

 

Just out of curiousity, what amp alternator did you get from Autozone? Advance ordered a 120amp for me which their catalog showed would fit, it did not line up. The 108amp would have been the correct one, that's what came on the car.

 

All brackets are on and double checked including all of the small support brackets. Changed during testing the A/C bracket thinking that it may be bent or something, but had the same result. Fortunately I have a complete spare L98 and able to compare and change parts. I even measured the A/C pulleys distance from the edge of the compressor body to the edge of the pulley and they are exact and no play.

 

I will check on that today.

 

Checked the alternator it's the DL-1348-6-11. It shows in the specs page to be 105.

http://www.autozone.com/autozone/parts/Duralast-Alternator/1986-Chevrolet-Corvette/_/N-ij0ktZ93xme?itemIdentifier=120018_23521_ 4443_