Belt making humming noise idling...

[Fiat88]

I replaced my timing belt a few months ago and now that I've been driving the car I've noticed that the belt is making a humming noise when its idling in Park(Automatic) at low RPMS but when revved the noise goes away. Does it sound like maybe the timing belt is too tight? I can twist the belt only around 45 degrees between both top cams. Thanks.

[124JOE]

it might be the belt tentioner berring

hope this helps

[majicwrench]

belts whine or sing when too tight, so yes, it could be too tight. Could be lots of things tho..
Keith

[Fiatmonkey]

I second the vote for the bearing.
Buy a stethoscope at a local parts store, it's one of the best $15 you will ever spend. Then you can narrow down where the sound is coming from.

Ahhh to have the ears of a Monkey!

[Fiat88]

I replaced the tensioner bearing about a year ago. I'm thinking the belt is just too tight.

[124JOE]

tentioner should be 55lbs

[So Cal Mark]

easy to check the tension, the stretch of belt inbetween the aux shaft and intake cam should be able to twist 90 degrees. If it won't twist that much, it's too tight.
BTW, do this test with the engine off

[Fiatmonkey]

LOL engine on test and we can nick name that person No-Fingers-McGee.

[Fiat88]

easy to check the tension, the stretch of belt inbetween the aux shaft and intake cam should be able to twist 90 degrees. If it won't twist that much, it's too tight.
BTW, do this test with the engine off

I checked the tension and the belt twists about 90 degrees.

[majicwrench]

That 90 degree test is pretty subjective unless you do a lot of Fiat belts. When it doubt, set the tension by letting the tensioner do the work. then tighten it up. I alwasy suprizing how loose the belt can seem and still be set properly.
Keith

[Fiat88]

I suspected it might of been the alternator belt which was too tight. I readjusted the tension on it and no more noise!