1994 530ia Belt Squeal/Moan

[mwillis3]

Recently purchased this car over eBay from California original owner. White with black leather; 86,000 miles; beautiful shape; $7000. Had the tranny rebuilt; all other rubber items replaced including the tires. Now have a great car for about $10K. Love it!

But...
I have a continuing problem with belt noise. I have replaced the two multi-ribbed belts as stated above. Also replaced the idler pulley and checked tensions. Adjusters are all maxed out, and belts feel just adequately taunt. Is the continued noise from a 'too tight' or a 'too loose' condition? Tensioners themselves worn-out? Did I pick a bad day to quit sniffing glue?

Thanks in advance.

[Kalevera]

So....where'd you get the parts?

best, whit

[mwillis3]

AutoHausAZ.com

[Tiger]

you replaced both idler pulley? Each tensioner has its own pulley.

[joshua43214]

your adjuster should not be maxed out. Either you have the wrong belts or a wrong pulley. Isolate which belt is causing the sqeal by removing or loosening the belts one at a time. very carefuly check pulley alignment, if a pulley tilted or not in the same plane as the others, it can cause noise. Low quality belts can be noisey out of the box, so can an over tightened belt. I see over tightened belts all the time, belts only need to be tight enough to do there job, any tighter causes premature wear on parts. Easy rule of thumb, ribbed belts with 4 or more grooves are tight enough when you can twist it 90% with thumb and first finger over its longest span, if it feel "hard" over a long span, it is overtightened. Narrower ribbed belts and V belts are about right when it will deflect about 1/2-3/4 inch with the tip of your index finger. The belt should run flat at idle and bow a bit at about 3k rpm. when you snap the throttle open and shut, it is normal for the belt to flutter a bit.

BTW, an over tightened belt will normaly make a whining or moaning noise from traped air not being able to escape. A loose or miss-aligned belt will make a sqeeling noise.

Keep in mind that a belt drives components from the side of the V portion (this is true of ribbed belts as well), what you want is for the side of the belt to make good consistant contact with the pulley, over tightening deforms the side of the belt and actualy in counter productive. Ribbed belts have greater surface area for contact and use the bottom of the rib (on the belt) as well, so require lower fewer degrees of pulley contact and lower tension to function.