Can't stop alt belt screech - 1.7d

[jamiehamy]

Looking for some ideas as I'm pretty stumped and getting peed off

Last year was driving to Islay and the alternator belt started screeching constantly (1.7d). Ended up removing it and driving without. Horsed it up when i got there and thought it was fixed, but came back on way back home, so removed it again.

Replaced both bearings on the alternator and the bushes and regulator just in case. Still not fixed. The water pump is fairly new.

Recently however it only screeched for a minute or so after startup. I tried various 'tightnesses' to not avail. Ordered a new 9.5x875 belt from JK which was a struggle to get on and made the problem worse, so back to old (and longer looking belt).

The other day it snapped (all bubbled so looks like it had gotten too warm). Fitted the 'new' one, and screeches all the time again. The pulleys are very warm too (result of screeching).

I am losing the will to live, this is over 6months I've had the issue and can't seem to fix it. Runs fine without the belt but obv not charging.

Any ideas anyone? I'd be very grateful

Thanks, Jamie

[Oldiebut goodie]

Most of the belts are 10 x ... are you sure that you should be using 9.5 x ...
Measure your pulley to check - I have a suspicion that you are just running the belt on the flat at the inside of the pulley rather than in the v.

[terryvanman]

A tip a mechanic told me once, was to put some talcum powder on it,,,it wont fix it and it wont last long but it stops the screech,,allegedly

[jamiehamy]

Thanks for the suggestion goodie. Will try pic up a 10 today, tho VAGCAT and most sites seem to suggest 9.5. I'm prepared to try anything to get it resolved!

J

[California Dreamin]

A 10mm profile belt will ride considerably higher in the pulley's and drive off a clean surface. The belt will be stronger and be less prone to stretch.
Have you checked battery charge rate as there is a posibility of a faulty regulator causing over charging and higher resistance to turn (hence the squeeling) definately worth checking. Charging voltage across the battery at 2,000rpm should read between 14 - 14.5 volts...with a faulty regulator this may be much higher..anything more than 14.7 and I would be changing the regulator brush pack as well as the 10 X 875 belt.
You mentioned the 9.5 X 875 belt was tight so the 10mm wide belt may need to be slightly longer..890 perhaps.

Martin

[Oldiebut goodie]

As the regulator,bearings and water pump were changed I would have thought the alternator/pump setup was OK.
Maybe you have mis-matched pulleys - someone has put a different alternator on without using the original pulley? Worth checking also?

[Plasticman]

Sounds more like the crank to waterpump belt slipping especially when it has to drive the alternator,
as you said it first squeeled after you start, hence current drain to replenish .
you took the belt off and prob went , which to me means the lower belt coulkd cope with the water pump mand thats it, the split pulleys can cause no end of grief
mm

[jamiehamy]

The alternator pulley gets very hot, which is why I'm fairly certain that's the issue. The difference between the old belt and the new is that the old one seemed longer and thinner. Because it was longer, I had to bring the alternator further round to tighten - I wonder if that might be aything to do with it as this would in theory allow more of the belt to be in contact with the water pump pulley?

Checked the 'new' belt this morning - it was already 10mm (despite the order being for a 9.5), so will try a 9.5, but no idea where to get one. I wish I could get a proper VAg one, but tried and not stocked anymore. The water pump belt looks different and has genuine VAG logo's on it (greeny colour?). VAGCAT says 875, wonder if I should try longer, maybe 900.

Not sure if the alternator is the original 1988 one,it's a Bosch one. Will try get a multi-meter and see what's going on there. Will keep posted, thank you for all the suggestions so far,

Jamie

[Oldiebut goodie]

Are the pulleys exactly in line? - you can soon check with a long straightedge - see if it touches the pulleys in 4 places.
Are the pulleys vee width the same on both?

[Plasticman]

As ^^^oldie says^^^^ also could suspect the alt bearing if its getting hot, this would squeel as the alt pulleys dont ususally slip
mm

[jamiehamy]

Just been down and fitted a new 10x875 but no change.

I checked the alignment of pulleys by eye (don't have a slim enough straight edge) and it looks like the alt pulley may be sitting out by 1/1.5mm. I'm also going to try a longer belt tmrw just in case.

I'll try a multi meter, but don't think it's a charging issue as there is no change in the sound when you load up the electrics, but will still try to be on the safe side.

If this fails I'm going to have to park her up as she's not drivable. Taking her to my parents tmrw but will run without the alternator belt on. Micky - the bearings are all new on the alternator and made no difference when they were fitted.

Cheers, J

[Plasticman]

Ah, theres something fundamental and more than likely simple wrong , be easy enough if it could be inspected. where abouts are you
mm

[jamiehamy]

Up near Glasgow! My tools are at my parents, so should be able to get a better idea in the morning.

Fingers crossed!

[California Dreamin]

I'll try a multi meter, but don't think it's a charging issue as there is no change in the sound when you load up the electrics, but will still try to be on the safe side.

Cheers, J

is no change in the sound when you load up the electrics Well there should be! .......With fully charged batteries and no consumers turned on the alternator is doing very little (a few amps for the ignition)...so turns with very little resistance.
Turn on the heater blower/headlamps and heated rear window and the alternator finds itself loaded with 30 - 40 amp discharge and a resistance to turn occurs due to the increased magnetism withing the rota as the alternator charges.

Martin

[jamiehamy]

Riiight!!

Checked alignment of the pulleys, they were actually all in-line with each other. Checked voltage and charging as per suggestion below (maybe slightly low tho).

I checked the pulleys and noticed that the alternator belt on the crank pulley sat about 1.5mm above the pullet, as opposed to almost flush for the water pump pulley. Back to Halfrods and took a chance with a different type of belt - not the toothed v-belt, but a flatter one with groves round the circumference.

Fitted it and not a squeak!! Fingers crossed that was the issue. This type of belt is similar to the one on the waterpump. Strange that JK and Halfrods both prescribed a toothed v-belt.

Anyway, thanks everyone for your help and suggestions, I really appreciate it - I don't think I'd have found the issue with them! I'm feeling much happier now, was really getting me down!

Jamie