alternator belt continues to slip.

[learnerZpermit]

as stated, ive went through 2 belts now. and i tighten them down (not overly tight) and the work for awhile. then if i drive at night and turn on my headlights, the belt squeals like a "live pig in the fire". so i get out, belt has a lot of play. i adjust the alt. mount. drive for antoher few days. same thing will occur. could it be the lock washers on the sliding mount? i didnt use new ones. didnt change the alt either. just been using the one that came with the car. oh yes, it is a 81' ZX. and there is no leaks from the water pump. the belts used are good quality. the only other thing i can think of is if the pulleys are off balance? but when in motion the belts dont seem to move much, as if they were "out of whack"? could a pulley be dragging? could the mount be coming loose little bit by little bit? and "stretch" out the belt so that it slowly squeals?

[Arne]

Try tightening it as before, but mark the position of the bolt on the upper mount. That way you can determine if the adjustment is changing, or if there is some other issue.

[sblake01]

Only three things could cause this. Dragging pulleys, like you said, caused by bad bearings in the water pump or alternator. If this was the case I would think you'd have other problems more serious than wearing out belts. Pulleys out of alignment e.g. a bent pulley on either the water pump, alternator or a worn dampner on the crank pulley (my opinion of what your problem is since I have seen that before). The other thing would be the wrong belt. Any of the aforementioned things would cause the belt to wear in such a way as to lose the tension and untimately begin to squeal. I doubt that the adjustment would move even without a lock washer if it was tightened properly but take Arne's advice and mark it so you'll have a point of reference.

[learnerZpermit]

if it was the dampner on the crank pulley , wouldnt the motor be vibration prone? i just replaced the water pump a month ago. seems fine,one of the nuts are gone though. i wouldnt think that one nut missing would throw the whole assebly off though? would it? i've learned centrifugal physics, so my understanding of the dynamics on this situation is good. i know that by it missing, the pulley could be thrown off balance, but that should be visible to the eye should it not?

[sblake01]

A bad dampmer wouldn't necessarily cause engine vibration. The pulley is bolted solidly to the crankshaft and the rubber dampening material is between the pulley and the surface where the fan belt runs. You might not notice the wobble at low speeds if the rubber was defective. But at higher speeds it could move around enough to put extra stress on the belt. The nut missing on the water pump pulley wouldn't cause the problem but I'd put one on there just in case any of the other three decide to loosen up. But like I said the problem you describe could only be caused by bad belt alignment, problems with any of the pulleys/bearings involved, or the belt itself.

[RogerZ]

well what is not overly tight. if you aren't getting enough belt tension it would do what you are describing. lights throw extra load on the alternator and belt squealing like stuck pig is what you get. You don't want to play high C when you pluck the belt but if you can push down with your finger more than 1/4 inch she be toooooo loose.

[Darrel]

Did you tighten the pivot bolts that mount to the engine block bracket?

[a7dz]

One more thing to check is the alignment of the alternator bracket. Is the belt running in a straight line or has some one taken the bracket off and not realigned it when they put it back or is the bracket loose where it bolts to the block? I had one of the bolts come loose on mine and it did what you are describbing. Cocked the bracket just enough to cause this. Just my 2c.

[learnerZpermit]

wow, those are all things that i didnt think about. thanks guys, as always the tech support on this website is unlike anything elsewhere. the honda guys used to flame me for asking a simple question like this. and toyota guys just never answer?????? i will always luv nissan/datsun. from my first 240sx(and many more like it) to my first 260Z. nissan and datsun haev always been there for me. this is the reason why i like cars more than women!!!!!!!!