High pitch whine with new Aux belts

Technical Area Engine, Transmission, Exhaust etc
2

I changed both the alternator belt and AC / PS belt on my 1990 roadster today as they were both sqealling like a pig.

I installed and tensioned the new ones according to the mazda workshop manual, however now there is now a horrible high pitch whine that increases in pitch as the engine revs. I rechecked the belts and I cannot see anything wrong. The noise seems to be coming from the alt belt not the ac/ps belt.

The new belts were supplied by mx5 parts and the markings showed they were correct length. I did notice that the old alt belt had no serations/teeth on the inner side, but the new belt has teeth. I assume this to to aid flexibility of the belt as it goes round the pulleys and don’t think it’s an issue as it fits in the v grove no problem.

Does anyone know if it the grooves causing the whine? It not what do you think is causing it.

Has anyone else fitted the mx5parts alternator belt and had the same problem? Would i be better off getting a genuine mazda belt.

I cannot live with the noise! Any help will be appreciated.

Si_G

 

3

Mine made this noise when the belts were first put on. Sounds like a very quiet supercharger!

 

The noise died down after a while but has come back since removing the belts and putting them back on again. I expect they might be a little too tight, I’ll slacken them off a little bit tomorrow to see if it makes a difference.

4

 

Have exactly the same problem.

Happened 2 belts ago with me as I have tried different belts to get rid of the noise. Even got a guy from miata.net to ship over a plain V belt to see if that made a difference.

I have tried running the car with both belts (PS, A/C) then WP / ALT belt on its own still with the squeal

and then briefly with no belts and the squeal was gone. I have also tried slackening the belts until they are slipping with no effect on the noise.

I have to assume I damaged the bearings in either the Alternator or the water pump by applying too much tension when installing the belts the first time around. My bets are on the Alt. Gonna buy a stethoscope to make sure before spending MORE money on Wifes Bain :slight_smile:

5

Thanks for the replies gents.

I’ll try slacking off the belts and running each belt on it’s own to see try and work out where the noise is coming from.

Hopefully it isn’t a bearing!

Stewart, good luck in using the stethoscope. Let us know what you find when you get round to it.

6

Has anybody solved the whining problem with the Dayco cogged alternator belts?

I have just fitted new alternator and PS/AC belts and now I have the annoying whining noise. Both belts are Dayco belts supplied by MX5Parts and the alternator belt is cogged. The old alternator belt was plain. I have slackened both belts to no avail.

I have used Bosch cogged alternator belts on other cars in the past with no issues. The last time I heard a whining noise like this was on a Nova just before the cam belt broke …