Hoping someone can help identify the cause of a squealing noise coming from my TDi. I've done a number of searches and have been unable to find anything that seems to fit the bill.

I've attached a short video of the noise which seems to be coming from the diesel pump area. It's not the auxillary belt as I replaced that two weeks ago and its not originating from anywhere near the starter motor. Could it be a bearing on a pulley??

The video:

Please help, I don't want to keep driving it if something is going to fail potentially causing major damage to the engine.

Thanks

Dan

Edited 20 March, 201214 yr by D16vGTi

maybe its the water pump,or the alternator, it sounds like a dry bearing.

If its a dry bearing, what's the best way to rectify the problem? would wd40/gt35 solve it?

or aux belt tensioner?

I thinking aux belt tensioner, sounds like the chatter you get from it. What happens noise wise if you hold the revs steady at a bit over 2k and then let it drop straight back to idle?

Why did you change the aux belt?

Is it worse when the engine is cold?

Also try turning everything electrical on (headlights + foglights, heated rear screen, fan and anything else that will use power) and the air con and see if the noise gets worse or more frequent.

I was going to do everything you suggested I try Trundlenut but it hasn't made the noise today....bizarre!!

I'll try it when it comes back but from memory the noise didn't change with the engine revs/speed.

It's often difficult to determine the source of a noise.

Get a large screwdriver, put the handle to your ear and rest the blade on the timing belt cover. It will act like a stethoscope. You want to make sure the noise isn't coming from the timing belt/idler pulley/tensioner.

Are all the various bits of the plastic undertray in their correct place? Nothing that could be rubbing on the belt or catching on something.

I found that the when the pulley was starting to fail the noise was intermittant, it was generally worse when the engine was cold. The pulley was still working on my car but it was stiff compared to the replacement. On a friends car the pulley was completely siezed and even then the noise was did not happen all the time.

But as Rbaldwin says there can be a lot of sources of funny noises.

I would put money on the alternator pulley being seized.

It should be a clutched one way pulley. There is an easy way to test though. Very gently with a this screwdriver and the belt on try to turn the fan blades in the alternator. They should move one way freely, but won't move the other. If they won't move either way the pulley is seized. The pulley is available on its own but requires a special tool to hold it (see my tool thread), requires the alternator removing to change it, that's fiddly but not difficult. I find it easier to remove the air con compressor (if fitted) and drop it down (pipes still connected).

on my 110tdi I couldn't work out how to get the alternator out the bottom, it shares a bracket with air con pump which got completely in the way even after I undid the pump and dropped it down.

It will come out the top but you have to remove the power steering pump (just undo it from the bracket) and IIRC I had to remove one of the fans to get enough space.

In order to undo the power steering pump you must undo the three bolts on the pulley BEFORE you remove the aux belt, otherwise you can't hold it still to loosen the bolts. With the pulley off you can get at the bolts that secure the pump. And this is exactly what I didn't do the first time!

same here, on my 110 I ended up come up with the alternator rather than down. Even when I removed the bolts for the alternator the bushes had moved and it took me ages (30 mins) of wiggling before the thing eventually came out.

I removed the PAS pump, and one of the fans of the rads too. I removed the aux belt, and then jammed a screwdriver into the gaps in the PAS pulley to stop it from moving while undoing the allen keys with a socket mounted key.

Guess its easier on a ramp. But you can rotate the alternator round and it drops out the bottom.

But either way, it's gotta come out.

Thanks for all the replies, I'll try the screwdriver test on the alternator and see what happens, if its not that then I'll have to wait for it to come back to try and locate the source using the screwdriver method.

I'll keep this post updated with any progress for future reference.

Thanks again

Dan

The alternator still moved on mine but when I compared the old pulley to the new one you could tell it was on the way out.

If it does make the noise again try watching the tensioner, if it is vibrating or actually bouncing around then that also suggests the pulley is knackered. On my car the damper on the tensioner shat itself and all the grease came out which was a good indication of a problem.

at beggining of video it sounded like dry bearings on pas pump, is there enough fluid in reservoir?

Yes its been recently serviced by skoda

Still no return of the mystery noise. I'll be doing a lot of miles over the next week so hopefully I'll get the chance to investigate.

Thanks all