Fan Belt Noise

[mimfarook]

Hi Guys,

I have an issue, I used to get a noise from the fan or a/c belt and subsequently changed both with new ones.

As advised by the mechanics I drove the vehicle around for about a week or so and tightened the belts and the noise disappeared.

Now almost two months later I am still getting the same noise. I read somewhere in the forum something about the belt pulley or teeth slipping when polished.

If this could be the cause can anyone suggest me someplace I could go and get this sorted out.

Thanks.

[nano31]

Hope it is not the related bearing noise. Try pouring some water on to the belt, if the noise coming from the belt it should be disappeared when the belt get wet. Check the tension of the belt as well.

What was the brand of the belt? ("Mitsuboshi" or something)

In my car (CE110) the noise disappeared when I put the original belts ("Bando" from Toyota Lanka, Rs 4000/= for both betls); I tried all most all types of belts avilable in the local market but only the original belt solved the issue.

[CJ5]

changed both with new ones.

Are you 100% sure they were in fact changed????? I know of many instances of owners being duped by crafty mechanics.

If you are not 100% sure that they were in fact changed then very likely they are the same old belts squeaking, and if you are 100% sure that they were in fact changed may be they just need to be adjusted some more, or else they could be some inferior belts that you got as replacements and are now again due for replacement!!! Just a possibility.

Edited July 11, 2013 by CJ5

[dreamracer]

hi just sharing my experience,we had the same problem in our car(cedric y33)

mechanic tightened up the the belts,problem was solved

[MV-5]

once these belt has been replaced, after 2-3 weeks (might be few hundred km), then belt should be adjusted again.

anyway i know that this will not help you, but i give you a TIP,

turn off the AC first

.if you get the noise just after started the engine and then noise gone away after 15-30 seconds(just after this try to turn on headlights , then noise might appear again) , then it is probably Alternator belt.

So at least you can eliminate one path :-)

[mimfarook]

hey everyone.. sorry i did not follow up on the issue.

the problem still persists. The belts are infact new ones which i replaced in May. Have tightened after a few hundreds of KM but still I am getting the noise.Even put water and checked. but not resolved yet.

I was told that it could be the alternator that is giving this noise.

Any thoughts on this?

[Rumesh88]

hey everyone.. sorry i did not follow up on the issue.

the problem still persists. The belts are infact new ones which i replaced in May. Have tightened after a few hundreds of KM but still I am getting the noise.Even put water and checked. but not resolved yet.

I was told that it could be the alternator that is giving this noise.

Any thoughts on this?

Seems to have along history. Are you sure that all your pulleys are in alignment? They may go out of alignment if you replace alternator or AC compressor with non-OEM products. Otherwise you need not worry on this. If you have a idler wheel get it checked for excessive play. Also assuming you have a poly V belt just see if the outer ribs of crank pulley or alternator pulley has become polished and shiny. If so you may have to get it a teeny bit machined.

[sharky]

Hope it is not the related bearing noise. Try pouring some water on to the belt, if the noise coming from the belt it should be disappeared when the belt get wet. Check the tension of the belt as well.

What was the brand of the belt? ("Mitsuboshi" or something)

In my car (CE110) the noise disappeared when I put the original belts ("Bando" from Toyota Lanka, Rs 4000/= for both betls); I tried all most all types of belts avilable in the local market but only the original belt solved the issue.

I had the same experience as above, replacing with the original (Bando) belt eliminated the noise, plus the noise did return a few times, each time I got the mechanic to tighten the belt. So far so good. I don't think it's recommended to use water to eliminate the noise. AFAIK you can use water to differentiate the source of the noise. i.e. pulley misalingment or belt slip.

[mimfarook]

ok. so i took the car to a renowned A/C place in kohuwela and got them to have a look. they did hear the noise, also checked the belts prior to this. didn't need to put water as it was raining that day.

finally had a look at the rpm level with AC on and AC off. noticed that the rpm decreases before coming to normal when AC is switched on where on the other hand when i switch off the AC the RPM increases before coming to normal (800 RPM) .(was told that the RPM is supposed to go up when AC is switched on).

They said that this should be the problem. asked me to go to any local garage and do a tuneup and also check the throttle. didnt have time yet.

Any opinion on the above comment?

[mimfarook]

I had the same experience as above, replacing with the original (Bando) belt eliminated the noise, plus the noise did return a few times, each time I got the mechanic to tighten the belt. So far so good. I don't think it's recommended to use water to eliminate the noise. AFAIK you can use water to differentiate the source of the noise. i.e. pulley misalingment or belt slip.

I had the same experience as above, replacing with the original (Bando) belt eliminated the noise, plus the noise did return a few times, each time I got the mechanic to tighten the belt. So far so good. I don't think it's recommended to use water to eliminate the noise. AFAIK you can use water to differentiate the source of the noise. i.e. pulley misalingment or belt slip.

Seems to have along history. Are you sure that all your pulleys are in alignment? They may go out of alignment if you replace alternator or AC compressor with non-OEM products. Otherwise you need not worry on this. If you have a idler wheel get it checked for excessive play. Also assuming you have a poly V belt just see if the outer ribs of crank pulley or alternator pulley has become polished and shiny. If so you may have to get it a teeny bit machined.

ok. so i took the car to a renowned A/C place in kohuwela and got them to have a look. they did hear the noise, also checked the belts prior to this. didn't need to put water as it was raining that day.

finally had a look at the rpm level with AC on and AC off. noticed that the rpm decreases before coming to normal when AC is switched on where on the other hand when i switch off the AC the RPM increases before coming to normal (800 RPM) .(was told that the RPM is supposed to go up when AC is switched on).

They said that this should be the problem. asked me to go to any local garage and do a tuneup and also check the throttle. didnt have time yet.

Any opinion on the above comment?

[Rumesh88]

Belts do tend to slip when the revs come down in "some" vehicles but not in all (For example post 90 Hondas with their ELD units and Pugs with ECUs cut off or reduce the alternator load when the revs comes down below a preset value. This prevents belt slipping to an extent). Hence, making the idle stable by tuning up the engine would be a solution at least for sometime. However, the core issue may be in a mismatch between the pulley and the belt. Ideally the belt should wedge on the pulley without touching at the vertices or the flattened (truncated) bottom part. If your vehicle (you've not mentioned what it is) has a power steering pump, the belt should not slip at idle when you turn the steering to one of the extremes with all electrical loads on. This is the bench mark test for it is then the load on the belt is at a maximum.

Edited October 23, 2013 by Rumesh88