Mazda 323 - screeching belt

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Fri 1 Apr 2016 17:10
Mazda 323 - screeching belt - tattylashes

Hi, can anyone please help, im at the end of my tether. last year my fan belt started making screeching noises, then just before Christmas the belt broke, we got it replaced then a few days later the new one started screeching too, we tried lubricants etc, to no avail. Then the car started to lose power so the battery was checked and it was fine, so we were told it was probably the alternator. So we got a second hand one put in and for two days it worked fine, then the screeching started again and the again ther battery wouldnt charge. the garage said the alternator wasnt working, so we got a new alternator and for 2 days it worked fine, then the screeching was back, so the garage said it can only be the water pump now, so replaced it free for us, ive just picked it up from the garage and less than a mile down the road the screeching has started again. mechanic has just said hes tested everything and it seemed fine so he is completely baffled.....

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Fri 1 Apr 2016 19:56
Mazda 323 - screeching belt - Wackyracer

Maybe the pulley on the crankshaft is worn and the belt is slipping on it or there is a problem maintaining belt tension.

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Fri 1 Apr 2016 23:12
Mazda 323 - screeching belt - tattylashes

Thank you for the suggestions, I will certainly look into it!

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Sat 2 Apr 2016 08:55
Mazda 323 - screeching belt - focussed

This sounds very much like the noise made by the front crankshaft damper pulley when the outer becomes unbonded from the inner.

If this is the case the alternator belt/story is a red herring, best get it checked out by a proper garage before it wrecks the engine.

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Sat 2 Apr 2016 12:47
Mazda 323 - screeching belt - tattylashes

Thank you. We had the alternators independently tested and we know they weren't charging the battery, just a question- if it is the crankshaft pulley could this be the cause of the damage to the alternators? By driving it are we risking damaging our brand new alternator too?

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Sat 2 Apr 2016 18:07
Mazda 323 - screeching belt - focussed

If the outer of the pulley is slipping it won't drive the alternator properly, I can't see it would damage it as such.

If it is the pulley disintegrating, you will risk damaging the crankshaft.

To check if the bottom pulley is at fault, look at it when the engine is running. if it runs out of true it could be the pulley.

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Sat 2 Apr 2016 21:36
Mazda 323 - screeching belt - Cyd

Draw a paint line across the two halves of the pulley with a white paint pen (or tip ex). Get it to 'screech for a few seconds and then see if the two halves of the line are no longer aligned. This should confirm if it's the pulley.

Many years ago I suffered a broken woodruf key on the crank pulley of a Rover V8. This meant the pulley was spinning on the crank. Partial drive was maintained by the pulley bolt and it too screeched when it slipped. Luckily I was able to induce slip at idle by putting a heavy load on the alternator and so could see what was going on with the aid of a Gunsons timing strobe.

I was going to suggest checking the alternator pulley for the same type of issue, but as you've already replaced the alternator this is unlikely.

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