Whining sound from engine on idle, off throttle?

P

PaulHa

Member
Hi,

I am not mechanically minded and before I contact a garage for repair, a diagnosis would be helpful? I suspect the alternator belt or tensioner on my 90 TDI is slipping/wearing out as I am getting a high pitched squeaking/whining sound from the engine. The noise started last summer, occasionally on idle just after starting from cold and it would disappear when warm, but with more frequent use disappeared. Its now however making the noise all the time hot or cold, at idle and off throttle. The noise appears to disappear when the engine is under load/on throttle.

There is a video with sound: video here - I assume this is the alternator belt?

I suspect its the original belt, the car has done 75K miles and I haven't changed it in the 11 years I have had the car. The car has only been going out once every 2 to 4 weeks during COVID, mainly on long journeys.

Any advice, diagnosis, recommendations would be very helpful.

Thanks,

Paul
 
Check the alternator overrun pulley. Worth replacing the belt and pulley and any idler puller. What about the cambelt water pump and tensioner?
 
Cambelt and water pump were replaced 18 months/1500 miles ago, so I am hoping the noise isn't coming from them?
 
Definitely alternator freewheel pulley. Oscillating tensioner is a dead giveaway.

Thanks,

Matt.
 
Get the overrun pulley changed (possibly with tensioner pulley) asap before it sheers off and rounds the threaded end of the alternator shaft - I made that mistake a calendar year ago. Pulley on Ebay from INA should be less than 25 quid give or take sporadic Ebay discount codes etc. You've got probably ~ a fortnight of real use to do this before it dies properly now (give or take a few days). On mine, it threw the belt first so I replaced that - but carried on making sporadic chirping noises for another couple of months of use twice a week or so until the alternator pulley ate itself and threw the pulley remains onto the undertray having ruined the splined end that you normally undo it from. Alternator was by then so badly sh***ed (one alternator bolt also sheared off while trying to undo it as well) that it needed to be hacked off in halves with a plasma cutter and replaced in entirety.
 
Thanks for the advice. I been to the garage today, they are looking next week to try replacing both the pulley on the end of the alternator and/or the tensioner depending what happens when they start taking it apart.
 
PaulHa said:
Thanks for the advice. I been to the garage today, they are looking next week to try replacing both the pulley on the end of the alternator and/or the tensioner depending what happens when they start taking it apart.
Click to expand...

Please update this because i have very similar sound :rolleyes:
 
Vic said:
Please update this because i have very similar sound :rolleyes:
Click to expand...
Garage replaced alternator pulley, tensioner and belt - said alternator spline was ok, but seized pulley had probably seized the tensioner? 1 hour labour plus ~£130 parts
 
Just read this after the missus came home with a the car smells burning. Having a look the alternator has sheared off. Can I drive it until I get a replacement as long as I don’t use lots of electric equipment?
 

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Charge the battery now it will need it after being driven without an alternator. You should then be able to drive a few miles to your local garage to have the alternator replaced, but nothing more than that really.

Andy
 
good idea on the belt tensioner bearing to check. Got a booking in at the garage and he reckoned he can remove the spindle from the alternator and replace the spindle and grooved belt wheel
 
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If replacing the alternator complete with a new over run clutch it is advisable to replace the tensioner and the belt. Can be a false economy to fit a used alternator unless sure of it history a refurbished is better if not a new one.
 
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Hi, thank you for your advice. The garage managed to get the pulley off and replaced it £42 along with a new belt £21 plus Labour for both bits but all back on the road :)


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audifan said:
As long as the alternator shaft was not damaged then good to go. Idler bearing OK?
Click to expand...

Yes asked about them to check it and the tensioner spring and all good. Passed the mot as well with a few warnings of a slight oil leak and tyres on the front are near limit :)
 
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