Technical fan belt chirp

[Matthew Kirk]

Today I fitted the new alternator and it's made no difference, annoyingly. I thought it would have been solved as the alternator once removed was rubbing slightly when the pulley was spun and the inner workings looked tired/worn.

The chirping noise returned when I started the car back up but my mate suggested that I put water on the belt and the noise went away temporarily and then came back. There is no pulley misalignment and the drive belt/tensioner were replaced recently.

I spun the air con compressor and the pulley spun freely.

Any help appreciated as always.

Matt.

 

[koalar]

Goes away when you pour water on it.


Sound like there is not enough tension on the belt.


Are you sure you have been supplied with the correct parts.

 

[Matthew Kirk]

Hi,

I ordered an SKF aux belt tensioner through Eurocarparts last year and fitted it. I also fitted a new drive belt at the same time.

I recall the car being quiet for a few weeks before the chirping reappeared.

Matt.

 

[koalar]

I use eurocarparts when they have a sale on.


Timing chain for my A Class arrived wrong twice. Always check against the original part before fitting.


Try lubricating the bearing on the tensioner. Changed the tensioner on the A Class for a very similar fault. Different sound but that would start to get noisy after about 20 miles. Would fit also that the noise went when it was last changed.

https://www.gatestechzone.com/en/problem-diagnosis/accessory-drive-system/tensioner-failure-signs

 

[Matthew Kirk]

Many thanks Koala,

I have no idea what it could be. The only thing that I can think of is pulley misalignment because when I sprayed water onto the belt the noise went away. However no pulleys are misaligned!

It's all rather odd.

 

[Matthew Kirk]

Hi,

I replaced my new aux belt tensioner with the old one and fitted another belt that I had as a spare. The noise was reduced immediately but only when the engine is hot, I still here a slight chirping in rhythm of the engine sound.

It is no where near as bad was it was though which is a good thing.

Matt.

 

[DaveMcT]

All you have left is the water pump or timing belt tensioner.

Run the engine with aux belt removed.

 

[Matthew Kirk]

Hi,

The fan belt noise has gone altogether. When I removed the fan belt the noise went altogether, so thankfully it was nothing to do with the timing belt/water pump.

Fitting the older belt (which is like new) and the older tensioner has made a massive difference. The car is now silent with no annoying chirping noises, even after a long (hot) motorway run.

Thanks for you help along the way.

Matt.

 

[A3jeroen]

Depending on the make of the belt, it might've been 5 mm's too long. Might've been within manufacturers spec, but just a little too loose.

gr J