whistling from fan/alt'/drive belt?

[ashleywengraf]

Hi everyone,
I have some squeeking/whistling that seems to be coming from the alternator? Possibly from the drive wheel side of things but definitely located aroung the belts that are obvious under the passenger seat. Only when engine is cold. For first 5/10 mins of starting.
Any help?

[stilldesperate]

Have you tried pouring a drop of water on the belt when it's running to see if the squeek stops?

SD

[platty345]

Might be the stud manafold problem.

[mikeonb4c]

Have you tried pouring a drop of water on the belt when it's running to see if the squeek stops?

SD

Good idea. Then if it still does it, rev the engine a bit and see if the squealing gets worse/louder as it might then point to the broken manifold stud scenario mentioned by platty345.

For what its worth, mine often (but not always) has a slight rhythmic (consistent with something being turned by the engine) squealing sound clearly audible on tickover. I used to worry it was a water pump on the way out. But 3 years and 25k miles later, it still does it, it hasn't got worse, and nothing untowards has happened.

[TEZ217]

would definitely go with platty345 MANIFOLD BOLT SNAPPED!
did this on mine some weeks ago and had the same opinion as yourself sounds like fan belt scream only there first thing while cold and under load, look under pass seat around where the noise is but look on the cylinder head mine was just under the lower front area of manifold and showed up as a slight soot deposit around the broken stud.

[ashleywengraf]

Thanks for all this. I recently had the problem with the manifold bolt and had it replaced. There was soot, also you could see a tiny spout of exhaust when starting that was causing the soot. That noise was far worse than this and, as you say, got worse when accelerating. Even when cold this noise stops when I rev, and there when I idle until it's warm and then it disapears completely. Someone else has suggested a drop of WD 40 on the belt to see if it stops it. Would that be because of a worn belt?
Appreciate all your help.
Ash

[stilldesperate]

I think the surface can glaze-over - maybe if it's been slipping, maybe through lack of use?

[bongoben]

I had same problem, squirt of WD40 stopped it but won't cure it.

Try belt tension and adjust if necessary.

If not:

Incorrect belts may have been fitted, or have worn on the side angle walls.

Fitting a new pair of correct belts usually cures the problem.

[ashleywengraf]

I think it is belt tension. Can't check until tomorrow am. when engine will be cold again. There are three belts in total? Two obvious on top and one running down. What is this to? How much tension/flex would be ideal? That is to say how much movement in the belts would be ideal?
Ash

[mikeonb4c]

I think it is belt tension. Can't check until tomorrow am. when engine will be cold again. There are three belts in total? Two obvious on top and one running down. What is this to? How much tension/flex would be ideal? That is to say how much movement in the belts would be ideal?
Ash

Twin belts for alternator etc. and one for aircon compressor I believe. I've heard the likes of Kirsty say you should be able to twist a belt through 90 degrees, as a rough rule of thumb, but I've not done this for years and am no mechanic. My rule of thumb though would be:

* Too tight is worse than too loose so be v. careful not to overtighten
* If it's too loose it should squeal as before.
* On my old motors you literally pulled the alternator/dynamo by hand and then tightened the
stay so it was v. hard to seriously overtension.
* Try the 90 degree check after all this to see if it confirms your approach as above

Hopefuly someone with more experience will comment/correct the above!

[bongoben]

The twisting method works with experience, but to be more precise,

If you have a pair of kitchen or bathroom scales then push down with
your thumb until you read 10 Kilogrammes. Get used to the feel of 10 Kg.

In the centre of the belts between the alternator pulley and the water pump
pulley, apply a pressure of 10 Kg with your thumb, and each belt should deflect
by no more than 10 mm. 5 mm is too tight.

To adjust the tension, loosen the top and bottom alternator fixing bolts and
turn the adjusting screw on the top bracket until you get the right tension.
Don't forgat to re-tighten the 2 fixing bolts when you're done.

[mikeonb4c]

The twisting method works with experience, but to be more precise,

If you have a pair of kitchen or bathroom scales then push down with
your thumb until you read 10 Kilogrammes. Get used to the feel of 10 Kg.

In the centre of the belts between the alternator pulley and the water pump
pulley, apply a pressure of 10 Kg with your thumb, and each belt should deflect
by no more than 10 mm. 5 mm is too tight.

To adjust the tension, loosen the top and bottom alternator fixing bolts and
turn the adjusting screw on the top bracket until you get the right tension.
Don't forgat to re-tighten the 2 fixing bolts when you're done.

Great advice. I'm almost wondering if that was what I was doing in the old days when you simply pulled on the alternator/dynamo (i.e.e sensing the tension) before tightening up the nut on the stay.

[ashleywengraf]

Thanks to everyone.

[Alison01326]

Hopefully Doone, or Allan himself, will read this and elucidate in case I misunderstood, but the last time I took my Bongo to Allan for a service I asked about it as it happens every morning and clears after a short while. I was told it was not uncommon and not a real problem and the belts stick a little bit when not moving particularly when they are damp (and as my Bongo is usually parked uphill facing the prevailing wind/weather). Mine is definitely worse if it has actually been raining all night.

This is unlikely to apply to everyone's whistling, but it was what I was told in my case.

[carlioll]

I also have a squeeking noise when the engine is on tickover and is cold. Not a squeal like a belt slipping. At the last service, Wheelquick said it isnt worth bothering about and is connected to the cold start system and is very common. The noise disappears when the engine is revved and when the engine warms up all is quiet on tickover.