alternator v-belt frustration

[lebowski]

what would cause the alt. v-belt on my 6.2 diesel to excessively slip and stetch? When i install new belts, I'm sure I'm tightening them enough.. well at least I think so, however I can't get a belt to last longer than a few months. With the heater blower, lights, and wipers going all at once the alt. gauge reads noticeably too low The alternator was recently rebuilt and a new pulley installed. Could i have an excessively worn crank pulley or water pump pulley causing this slippage? Thanks for any tips!

 

[supersize75k5]

how much movement do you have when you install the belt, you should only be able to move it a 1/4 inch or so.


you do not want it to tight either though

 

[lebowski]

when i put a fresh belt on, i get it pretty tight. The only other clue i see is in the motion of the belt when the engine is running. As the belt wraps around the alt. pulley and heads back down to the crank pulley, the belt seems to be vibrating, or shaking extremely quick all over the place as it heads toward the crank pulley. I wouldn't say this movement is dramatic, however it is far from smooth or unnoticable. I suppose if the crank pulley was worn, this may cause the belt to shift around a bit as it rotates through the pulleys eh?

 

[Jason4x4]

New belts tend to stretch, then need to be retightened.

 

[CHEVYDADDY]

Small question aligment of pulleys stright on? go with a shorter belt. instead of useing your full adjustment use as little as possible. this might not be the best answer but had it work for me.

 

[lebowski]

Well I'll give the shorter belt a try. It looks like each pulley is lined up pretty straight with the rest, however is there a way to measure this besides eye-balling? Also, do you suppose a new set of pulleys would be hard to find?

 

[GsxrMike]

Do the pullys have any groves in them? I know at work when I come across a piece of equipment that is eating belt there is usually a groove where the pully rides and it wears the belts out quick. Have you felt your belt after driving? Is it HOT? That would mean you are having some slipage and the combined with the heat will wear them out fast too!

 

[Wrench]

when i put a fresh belt on, i get it pretty tight. The only other clue i see is in the motion of the belt when the engine is running. As the belt wraps around the alt. pulley and heads back down to the crank pulley, the belt seems to be vibrating, or shaking extremely quick all over the place as it heads toward the crank pulley. I wouldn't say this movement is dramatic, however it is far from smooth or unnoticable. I suppose if the crank pulley was worn, this may cause the belt to shift around a bit as it rotates through the pulleys eh?

Definitely check your crank pulley and harmonic balancer, both have rubber in them unlike the gassers. What year is your diesel? The stock alternators are pretty minimal through the mid-80's. If you look for one with the plastic fan on the front, those are the higher output versions, but the best alternative is to do a serpentine belt conversion with the CS-130 alternator. I did it on my truck, pretty simple, and I come across the serpentine setups every now and then in junkyards.

 

[Mike D]

I know this might sound stupid, but when I changed my alternator from a SI 78A to a CS 144A it would wear out a new belt once a month. I only use the truck on weekends. I finally changed to a NAPA premium V belt, so far it's been 4 months and every thing still OK. The cheap quality "premium" Auto Zone belts were made in Mexico. They should change the AZ "premium" name to "el crapo".
GM was never famous for their belt alignment. If the pullies aren't in perfect alignment to each other, the belt will wear out faster. The new alternator pully may be off alignment.

 

[George_Pimpdaddy]

either to tight or to loose and yes they do stretch after a few hours on a new belt. also try to install em with clean hands