Belt screech on throttle dab

[Mark Elder]

A worsening fault my car has had for last few weeks is that, when cold (first few miles) and I dab the throttle (eg in a change down - so revs quickly rise from say 1500 to 2500) I get a screech from a belt in the engine bay.

All belts seem tight.

Anyone had this before? Could this be a bearing (eg on aircon pump) getting tight until car is warm.

It never happens once car is warmed up.

Thanks in advance.

 

[burrow01]

Hi

Belts may seem tight, but would still suspect them - any smell of burning rubber?

I think there is a special tool to check the belt tension is correct

Pete

 

[John Maddox]

You can spray water onto the belts and see if noise stops - avoid the alternator when doing this !!

 

[szklarek]

A good few years ago I had a similar problem - the OPC tightened the belts several times (and changed them once I think) and the problem didn't disappear. In the end they had to roughen up the surface of pulleys (or rather, just remove the 'glaze' as they seemed very shiny on the contact surface) so they would grip. Never had the problem again after that.

Kind regards
Anton

 

[clyde]

OPC changed the alternator belt on mine when they were changing a broken belt tensioner a number of years back and made a right pig's ear of setting the tension. The result was that the belt was too tight, made a screeching noise occasionally and snapped a few days later before I could get the car back to them. Fortunately it snapped literally as I was parking it in my garage so I wasn't stranded. To their credit they sent a low loader to collect it, fixed it (properly this time) and returned it without any issue.

It is apparantly a swine of job as you need to play about with various sized scims to set the two halves of the pully properly to enable the belt to sit at the right height in the pulley and therefore be tensioned correctly [8|]. Doesn't seem like an easy diy to me.

 

[szklarek]

Yes I agree, it looks like a really fiddly job - I've always had mine done at, originally, an OPC and now Northway's. Not only do you need various shims but I think there is a special tool required as well.

Kind regards
Anton

 

[MarkG]

An old remedy for noisy v-belts is to apply a light dusting of french chalk dust (the stuff you used to grate in the bicycle punture repair kits.)

 

[Guest]

If it's not belt sensor pulley (try removing sensor) and if it's not alternator bearings (feel/listen for rumble), sounds like the alternator belt pulley is worn/not tight enough. I couldn't get a new belt tight enough with no shims at all and on my 107,000 mile car decided to change the alternator pulley. Result: marvellous...no screech at all now. Roughing up etc will only provide temporary cure.

By the way, early pulleys can disintegrate and dent your engine cover, so perhaps the £90 spent is worth it to kill two birds with one stone? Current upgraded pulley is larger than the old one.

Hope this helps []