Drive Belt Squeal

[Chris81]

Well it's that time of year again where it's cold and damp on a morning and my drive belt squeals. Doesn't do it over the warmer drier months but as soon as this time of year comes, for the first 5 minutes or so of driving, the belt makes a chirp/rhythmic squeak. It used to disappear when you put a few revs on but it seems there throughout the rev range now until 5 mins or so when the belt has warmed up. I can only think the moisture in the air is the cause. The car's on about 40k, t-sport with hydraulic power steering so there's a second drivebelt for that too but I'm sure its the main alternator belt, as if I mist some WD40 on it then it disappears temporarily. Would you say it's worth getting the belt replaced, or see if a mechanic can tighten it? (I'm just a bit worried of them overtightening it). It's chirped ever since about 15k, looks in decent condition, the back is a bit glazed but don't they all look like that?!

[t-spiritpete]

Well it's that time of year again where it's cold and damp on a morning and my drive belt squeals. Doesn't do it over the warmer drier months but as soon as this time of year comes, for the first 5 minutes or so of driving, the belt makes a chirp/rhythmic squeak. It used to disappear when you put a few revs on but it seems there throughout the rev range now until 5 mins or so when the belt has warmed up. I can only think the moisture in the air is the cause. The car's on about 40k, t-sport with hydraulic power steering so there's a second drivebelt for that too but I'm sure its the main alternator belt, as if I mist some WD40 on it then it disappears temporarily. Would you say it's worth getting the belt replaced, or see if a mechanic can tighten it? (I'm just a bit worried of them overtightening it). It's chirped ever since about 15k, looks in decent condition, the back is a bit glazed but don't they all look like that?!

Hello, I think a new belt would be a very wise investment at that mileage .... why not give it a treat for Christmas ;).

Regards .... Pete.

[Madasafish]

After a few miles, they all look glazed.

The tightening adjustment is at the rear of the engine and is a simple matter of loosening a locking nut and turning an adjusting nut.(After loosening the alternator securing bolt - and then retightening when finished Accessible from the top of the engine on the 1.0 - even if not on the T Sport it would be simple to jack it up and remove part of the plastic shielding in the wheelarch.

About 15-30 mins work tops. Any competent mechanic should be able to do it... (I have and I am just an amateur)..

Unless the belt is cracking or really badly worn , no need to replace it. (they are very tough)

As for overtightening, unlikely unless really ham handed incompetents..

If I did not diy, I would trust my local run of the mill garage to do it - they are both competent and responsible.

Hope that helps.

[Chris81]

Madasafish thanks for the response - Would you say the symptoms I describe are consistent with a drive belt that is ever so slightly loose? I'm not competent enough to DIY tighten it myself so will need to visit a garage. It doesn't seem particularly loose - though I read somewhere if you grab it along its length inbetween 2 pulleys and can turn it through 90 degrees then it's too loose. At a guess mine moves through about 70 degrees.

[Madasafish]

Madasafish thanks for the response - Would you say the symptoms I describe are consistent with a drive belt that is ever so slightly loose? I'm not competent enough to DIY tighten it myself so will need to visit a garage. It doesn't seem particularly loose - though I read somewhere if you grab it along its length inbetween 2 pulleys and can turn it through 90 degrees then it's too loose. At a guess mine moves through about 70 degrees.

Chris

belts tend to expand with use.. So yours sounds it just needs gentle retightening..

[enyajtrebor]

Adjustment failed to cure the problem on our 06 plate Yaris T Spirit with 28k on the clock. Back to Mr T who honoured their 12 month warranty and replaced the belt.

Silence is golden !!!!

[t-spiritpete]

Madasafish thanks for the response - Would you say the symptoms I describe are consistent with a drive belt that is ever so slightly loose? I'm not competent enough to DIY tighten it myself so will need to visit a garage. It doesn't seem particularly loose - though I read somewhere if you grab it along its length inbetween 2 pulleys and can turn it through 90 degrees then it's too loose. At a guess mine moves through about 70 degrees.

Chris

belts tend to expand with use.. So yours sounds it just needs gentle retightening..

I thought replacement would be the best option as Chris81 said it had been squealing for the past 25k miles and if you are paying someone to do you may as well just pay them once with a 100% success rate (unless the pulleys are worn).

Regards .... Pete.

[Chris81]

Thanks all. I've had another look/poke and it seems plenty tight to me. Very little deflection when you tug on the belt. As I say, it only chirps on cold, damp days for the first 5 mins of driving. I'll pop along to my local garage and get them to take a look. I get the point about paying to adjust it/fit a new belt only once, though as it started chirping at around 15k miles, it doesn't say a lot for the parts quality.

[Cyker]

I always get this come winter too. :( I tend to ignore it as it's usually gone before I get out of my road!

[meritodt]

A drive belt is a seamless belt that is used to transmit torque and power from one wheel or shaft to another in a machine or any mechanical system, in this instance a vehicle. A belt drive system typically involves more than two fixed pulleys working together and is very important in the transmission of motion in a machine.

___________

genuine volkswagen parts

[Geoff Peace]

Firstly, the belt should be tightened until the deflection at the midpoint of the longest run is 8.5 -10.5mm [new belt] 11.5 -12.5mm [used belt] this is for models with hydraulic power steering. 4.5 -5.5mm [new belt] 6.0 -6.5mm [used belt] for models with electric power steering. This is with firm thumb pressure classed as 22 lbs. A used belt is one which has been running on an engine for longer than five minutes. Secondly the reason why belts squeel, providing that they are tight enough, is because whatever they look like they are worn. To explain, it is a common myth that belts stretch, they do not! What happens is that a V belt is designed to drive from the sides of the pulley it is also deigned to slip so it will wear and sit deeper into the pulley groove, become slack whereupon most people think it has stretched, eventually the belt will sink into the pulley far enough to try and drive from the bottom of the pulley groove, it will not do so, it will squeel and no amount of tightening it will make any difference. Modern cars have multi V belts but the principle is the same, the belt is worn and trying to drive from the bottom of the grooves instead of the sides. A new belt is the only remedy. Finally if anyone still thinks belts stretch, try to stretch one, I have seen them tested, they will support a good deal of weight before they snap, not stretch. I hope this will explain a few things and dispel a few myths.

Regards Geoff Peace.

[Chris81]

Well I had the drive belt replaced with a genuine Toyota part and it's made no difference at all to the squeak/chirp noise. I only tend to hear it on really cold mornings or when there's a lot of moisture in the air, and it wears off after about 5 minutes of driving.

If I had to guess I'd say it's coming from the lower part of the belt's travel, so could be one of the lower pulleys. I'm hoping it's nothing to worry about as it's had these symptoms for at least 3 years. I thought changing the belt would fix it but obviously not. Could it be (as I've read somewhere) the metal side of the pulleys just being cold/damp that causes this squeak?

[Cyker]

The only known way to get rid of it is to tighten the belt a tiny bit, but because this (seems to be) a temperature thing, that may cause excess wear on the belt come summer

As I said, on mine I just ignore it because by the time I've reversed out and gone round 3 corners it's gone :D

I suspect it's a mixture of cold and moisture/condensation that causes it tho'

This particular problem is a Yaris specific one, not a general belt-wear problem (Kinda like the Yaris-specific problem with the ARB bushes )

[Chris81]

Cyker, it does sound like yours has similar characteristics. On yours, does the squeak disappear when you put a few revs on, and return when the revs drop to idle?

[Geoff Peace]

Well I had the drive belt replaced with a genuine Toyota part and it's made no difference at all to the squeak/chirp noise. I only tend to hear it on really cold mornings or when there's a lot of moisture in the air, and it wears off after about 5 minutes of driving.

If I had to guess I'd say it's coming from the lower part of the belt's travel, so could be one of the lower pulleys. I'm hoping it's nothing to worry about as it's had these symptoms for at least 3 years. I thought changing the belt would fix it but obviously not. Could it be (as I've read somewhere) the metal side of the pulleys just being cold/damp that causes this squeak?

If it sounds as though there is a canary chirping somewhere it is not belt squeel. It may well be a dry bearing in the alternator or water pump. The only way to tell is to run the engine and listen with a mechanics stethoscope to pinpoint the cause. If it goes away after a minute or two I would not worry about it until it becomes constant.

Regards Geoff Peace.

[Chris81]

Cheers Geoff, you sound like the drive belt guru! I would say its like a chirp-chirp-chirp noise rather than a constant chirp if you see what I mean. Like a fast ticking clock, only the ticks are chirps. You could be onto something with the dry bearing.

Out of interest, in your post above about deflection, is this in one direction only? i.e. deflection when pushing down, or is it deflection if wiggling it up and down? According to the manual it looks as if it's in one direction only. I've had a look at my new fitted belt and it does seem to flex down around the 11-12mm with firm thumb pressure. Obviously that means 11-12mm in both directions.

On my separate power steering belt I'd say the deflection was more like 5mm down, and on my friends Yaris 1.0 which just has one drive belt it's also a lot tighter than mine at about 5mm deflection down. Wonder if there's any mileage in getting the garage to tighten it some more - will depend on your answer to my deflection question!

[Cyker]

Cyker, it does sound like yours has similar characteristics. On yours, does the squeak disappear when you put a few revs on, and return when the revs drop to idle?

Yeah; At idle it's a very annoying rapid squeeksqueeksqueek but as I raise the revs it becomes a continuous squeel but also fades (The magic point seems to be about 2k RPM where it goes completely.)

If I let the revs drop it will come back, BUT all the while the engine is running it is fading out; It's literally gone before I get out of my road

It is very weather dependent - I've only had it a couple of times this winter but it faded very fast. I know from previous years tho' that as the mornings get colder I'll be getting it more...!

[Geoff Peace]

Cheers Geoff, you sound like the drive belt guru! I would say its like a chirp-chirp-chirp noise rather than a constant chirp if you see what I mean. Like a fast ticking clock, only the ticks are chirps. You could be onto something with the dry bearing.

Out of interest, in your post above about deflection, is this in one direction only? i.e. deflection when pushing down, or is it deflection if wiggling it up and down? According to the manual it looks as if it's in one direction only. I've had a look at my new fitted belt and it does seem to flex down around the 11-12mm with firm thumb pressure. Obviously that means 11-12mm in both directions.

On my separate power steering belt I'd say the deflection was more like 5mm down, and on my friends Yaris 1.0 which just has one drive belt it's also a lot tighter than mine at about 5mm deflection down. Wonder if there's any mileage in getting the garage to tighten it some more - will depend on your answer to my deflection question!

Drive belt guru! Well I have been called a few things in my time but that is a new one! Mind you I have been fitting them for over sixty years so One does learn a little! To be serious, The deflection is one way, press down on the longest run keeping the belt square, very easy to tip it sideways and get a false reading. The alternator belt on the yaris is a 6PK that means it has 6 ribs and is quite a wide belt for a small car, most are 4PK. The interesting thing from your first post is that you say the noise disappears if you spray the belt with WD40. This indicates a fault with the belt. not bearings. Check that the pulleys are in line, put a steel ruler across them in one of the grooves, clean the pulleys, dirt causes problems. Belts will squeel when slack, but they can do the same when too tight or the pulleys are out of line. I take it you are not using the belt with WD40 on it if so a new belt is needed. Ideally a belt should be as slack as possible without squeeling, a belt too tight will damage alternator and water pump bearings. This is impractical as it would require periodic adjustment. I would stick with the manufacturers figures for tension. If everything seems OK an old trick is to coat the inside of the belt with french chalk, if it is stll obtainable, a tyre fitting shop may have some otherwise use talcum powder. Do not use any of the 'belt dressings' I have seen advertised,I have known them make things worse, belts are designed to run dry. Good Luck, hope this helps, let me know how you get on.

P.S. A belt should be marked, I use tyre chalk, so that if removed it can be refitted to run the same way, turning it round can cause problems.

Regards Geoff Peace.

[Chris81]

It was the old belt I sprayed wd40 on and yes, each time i sprayed it it made the chirp go away. Now with the new belt fitted the chirp is still there but I don't plan on using any wd40 on this one. However, I'm sure if I did, it would silence the noise temporarily. I may try the french chalk if I can get hold of some or the talc. Cheers!

[Chris81]

Does anyone know how to tighten the drive belt on a mk 1 Yaris? The Yank forums seem to only talk about undoing the alternator bolts but isn't there a tensioner or other bolts (as described by Madasafish) elsewhere?

[Geoff Peace]

Does anyone know how to tighten the drive belt on a mk 1 Yaris? The Yank forums seem to only talk about undoing the alternator bolts but isn't there a tensioner or other bolts (as described by Madasafish) elsewhere?

No tensioner. adjustment is achieved by slackening the alternator pivot bolt and then by the adjusting screw at the top.

Regards Geoff Peace.

[Chris81]

Cheers Geoff. I had the garage tighten it a bit more and if anything it's made the noise worse. I can hear it very faintly at idle all the time now, even when engine's warm. I'm thinking it must be a dry bearing somewhere, like you say, impossible to tell without a stethoscope, though it seems to be the crank or water pump rather than the alternator which is right at the top. I think I'll just see if it gets any worse and keep an eye on the coolant level. No sign of any pink crystals anywhere so if it's the water pump making the noise then it doesn't appear to be leaking. I trust a dry bearing in itself isn't too much of a problem.

[Chris81]

To follow this up, I'm now convinced it's the power steering belt that's making the chirp (diagnosis with misting wd40 on it which silences it temporarily) My model Yaris has a separate belt for the hydraulic power steering and I asked the garage to replace this when they replaced the drivebelt however they said the power steering belt didn't need doing! Grrr...

Now looking at it, the drivebelt will need to be removed again in order to get to the power steering belt, but how is the power steering belt removed? The drivebelt is tensioned via the alternator, how is the power steering belt tensioned?

Btw, Cyker, does yours have a separate power steering belt, as i suspect that's the cause of our chirp.