Alternator Bushes, to change or not?

[James_N]

Hi All,

My 940 seems to like eating alternator belts. They seem to last around 12 months, then snap!

My last one went just before Christmas and it took three hours to be recovered home! Anyway, this was replaced by a Genuine Volvo belt.

On giving my poor neighbour a jump start tonight, I noticed the belt moving around a little on the pulley and sometimes almost jumping around, as if it was quite slack. The edges of the belt look like they are beginning to fray a little as well.

All this is in a relatively short space of time. Its almost as if something is very slightly out of alignment and the belt is rubbing on the side of the pulley grove (if you can understand what I mean).

Would it be worth changing the Alternator Bushes, maybe to stiffen things back up and stop the movement? The car is getting on a bit now, and maybe its time to look after the old girl a little better than I have been over the past 12 months or so! Its MOT time next month and ive got a few things that need sorting, but having seen the belt looking a little slack and the edges starting to fray a tad, would it be something worth doing?

How much would I be looking at for polybushes (or just normal bushes!) and fitting at a local garage (I think labour is about £55 an hour).

Cheers
James
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[Steve940estate]

It does sound like something isn't straight. Is there any chance the belt was in the wrong slot on any of the pulleys ? Volvo helpfully gave you more belt grooves than needed to make things difficult. I struggled with mine as I had been supplied the wrong length belts which made things more tricky than normal.

A photo of your engine might help.

[James_N]

Originally Posted by Steve940estate

It does sound like something isn't straight. Is there any chance the belt was in the wrong slot on any of the pulleys ? Volvo helpfully gave you more belt grooves than needed to make things difficult. I struggled with mine as I had been supplied the wrong length belts which made things more tricky than normal.

A photo of your engine might help.

Not in the wrong slot (confirmed by looking at many pictures of the 230FK engine). I will post a picture tomorrow though but for the past few years belts have not lasted, even the genuine Volvo ones

[Steve940estate]

The easiest way to see if the alternator is twisted is to put a straight edge on the pulley. I suggested a photo as someone might spot something, worth a try anyway.

[bluebrickrick]

Stick a voltmeter across the battery, run the engine up (I keep a cut off bit of wooden lolipop stick hung on a bit of cord ied to the carb to jam the throttle open at around 3K revs for when needing to recharge or while jumpstarting someone) and watch the voltage as you progressively load up by turning on everything electrical that you have on board, (main beam, fogs, rear screen heater etc) if it holds the 13.5-14 ish volts you start with then the brushes are delivering enough volts through the slip rings to keep the output coils generating adequately so the electrical side ought to be OK. This will also put a heavy mechanical load on belt and pulleys so you should be able to see or hear if it is slipping or jumping which needs investigating, also worth checking that the key in the alternator shaft hasn't been missed from a previous re assembly.
If using a digital meter it may not register rapid voltage fluctuations as readily as a needle meter.
HTH

You will need a smaller than usual crimp and crimp ferrules if changing brushes yourself on the Bosch / Volvo alternator

[Rversteeg]

PE bushings are around 8 GBP each, you need three. Changing is a piece of cake and will take you about 15 minutes max.

[jor]

Another factor is the tension - apparently belts do not like to be too tight and a little pressure should give 1/2" deflection. For mechanical numpties like myself it's somewhat problematic to work out which of the fixings to alter to change tension in the correct belt. I've not had one go - yet, but as I can never manage to fully eliminate some degree of squeal will change every year.

jor