Pontiac Repair: Pontiac Transport 1994, pontiac transport 1994, crankshaft pulley

Question
QUESTION: This has parts from 3.1 to a 3.4L engine on it. What is happening is that it it throwing the serpentine belt of the bottom of the pulleys. The three that are at the bottom it the tensor pulley the crankshaft , and the air compressor. I have replaced the air compressor with a used one this last august, and then about 4 month ago I had to replace the Tensor pulley because it was bad. We would like to know if this could be the crankshaft harmonic balance, the car does start and run, that is why it is questionable to say that it could be the crank shaft, but could it be the pulley itself. Also we were thinking that it could be possibly a bolt, but unsure how to check on the crankshaft pulley maybe out of alignment. Thank you for your insight.

ANSWER: Hi Lori:

with out seeing it it's hard to say. but usually it's either a tensioner that goes bad and you said you replaced it or it's an idler pulley which is just a pulley that allows the bely to chnage directions and the belt bend around it. the bearings in the pulleys go bad. ther other possabilities are the crank pulley the rubber that is an insulator between the crank part and the pulley wears out and it allows the pulley to whobble and eventually throw the belt off. A water pump that is going bad if it has toom much slop in the pulley same thing. or the a/c compressor if it's seizing up can rurn up a belt and throw it off. that are all your choices what the issue is? I don;t know with out seeing it. good luck :-}


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QUESTION: Thank you for responding to me so quickly. If it could be the crank , that insulator that is between it how would you check to see if that is that, and how would you know if that could be the issue. We were thinking that it could be the air compressor , however we were concerned with the crank, and my brother and step dad are not sure how to check the crank and would like to know how to do so, thank you very much for your insight and help.

Answer
with a new belt on it you would have to look to see if you can visably see it whobble.the thing with them is as the engine gets hotter the rubber hets more plyable so cold it may "look" ok but when it;'s hot it not. when the engine is hot take the belt off and use a pry bar on the outter edge of the crank pulley and see if it moves alot or just a little The is not a spec for it it's a judgement call.