General Squealing on start-up - alternator belt?

[Fast Eddie]

had a 2nd hand alternator fitted recently with well used belt apparently

noise starts as soon as the engine kicks in and have noticed as it's got worse over the last fortnight that it squeals louder as the accelorator is squeezed

this squealing tends to last for about a minute or so - just enough for the neighbours to growl/laugh at me as i head off to work in the mornings!

i know these belts tend to get noisy, but i imagine all the belts do???

i'm also struggling to come up with a torque setting for the alternator adjuster seeing as i'll probably change the belt sooner rather than later - unless this squeal turns out to be something much more dark

 

[a1ant]

Hi mate,

Its quite likely that its a poorly adjusted auxiliary drive belt. However, another possibility is that a cam belt tensioner is on its way out. If its the later, depending on what engine you have, if it fails it could cause you some problems. However, i would start by checking the tension on the aux drive belt. If you can pin point where the noise is coming from exactly in the engine bay will also help you. You can use a cardboard tube or similar to your ear if you dont have an automotive stethascope.

Hope that helps,
Alan

 

[Fast Eddie]

cheers alan, tho that sounds a bit grim tbh!

do you not think the alternator belt is a likely suspect then?

i'll try and pin-point the noise a bit better - can do without paying a garage right now but not confident enough to check the main bits of engine really - just the bits around it (it's a jtd 1.9 - no Haynes grrrrrr....)

 

[a1ant]

sorry mate, the aux drive belt is the alternator belt! Its highly likely its just that!

Alan

 

[Fast Eddie]

sorry mate, the aux drive belt is the alternator belt! Its highly likely its just that!

Alan

aha, cheers that's better!

you mean poorly adjusted as in too tight? or a dodgy pulley on the cam?

if you could tell me the torque on the adjuster and the setting on the belt the cyber drinks are on me

 

[a1ant]

It could be too tight or too loose, both can cause squealing. In between the two pulleys, if you push on the middle of the belt with your finger, you want Just under 1cm of deflection in the belt. Any more and you need to tighten it. So as such, there is no specific torque for the adjustment, as it varies from belt to belt.

Failing that, then it may well be the tensioner on the cam belt.

Alan

 

[Fast Eddie]

It could be too tight or too loose, both can cause squealing. In between the two pulleys, if you push on the middle of the belt with your finger, you want Just under 1cm of deflection in the belt. Any more and you need to tighten it. So as such, there is no specific torque for the adjustment, as it varies from belt to belt.

Failing that, then it may well be the tensioner on the cam belt.

Alan

okay I think i've got ya

that's helped a lot so cheers. i've fitted plenty of alternators but usually on CAT engines. not actually that much more technical than on a punto by the sounds of it! anyway, i'll have a look over the weekend and see what i can do.

 

[Ralf S.]

Any belt that is worn can squeak because it's brittle and so just doesn't grip the pulley.

What Neanderthal fitted the alternator but used a "well worn" belt..

Slacken the alternator bolts, pull it forwards to loosen the belt.. stick a new belt on there (£12) then puch the alternator back so the belt is "tight". Tighten the bolts and check the belt tension. It just has to move 2cm when you press moderately on it.. don't make it so tight that it seems rigid.

Ralf S.

 

[Fast Eddie]

Any belt that is worn can squeak because it's brittle and so just doesn't grip the pulley.

What Neanderthal fitted the alternator but used a "well worn" belt..

Slacken the alternator bolts, pull it forwards to loosen the belt.. stick a new belt on there (£12) then puch the alternator back so the belt is "tight". Tighten the bolts and check the belt tension. It just has to move 2cm when you press moderately on it.. don't make it so tight that it seems rigid.

Ralf S.

cheers ralf.

breakers replaced alternator with a spare on the cheap but stuck my old belt back on it cus the one they had had snapped apparently

i think they wanted return business to fit a new one tbh, but anyway... the one thing they won't be getting (unless i prang it again!) is return business.

i'll check out the belt over the weekend hopefully. got a bad feeling it may well be something else as well going by a bad jolt i heard inside the lid on start-up earlier today (and once or twice recently) but we shall see...

ta again

 

[Ralf S.]

A jolt or bang on start-up may be the starter... but let's worry about that later.

A new belt is a joy.. Really you'll wonder why for the money people run them till they break.

Just don't over-tighten it or you'll strain the alternator bearings.. It should depress about 1" / 2cm when you press your thumb down on it. Push the alternator back as far as it will go and hold it there under some pressure while you tighten the belt. If you break into a sweat, it's too tight.


Ralf S.