Idiots' guide to replacing alternator belt please

[rosie]

My alternator belt snapped today. I have a spare but can't remember how to replace it - it's been a long time and the Haynes Manual is as unhelpful as ever. I've loosened the top bolt where the toothed adjustment is, but not sure what else I have to undo. Are there more bolts somewhere?
I think the alternator pivots/levers forward somehow to allow the belt to fit onto the top pulley?
Please can someone jog my memory and give me an idiot's guide?
Thank you.
It's a 1.8l mk2, no air con

[Tim_R]

Hi Rosie,

There is a 13mm at the other end of the bracket with the toothed adjustment which is best to slacken off and the allen head pivot bolt for the alternator itself, this behind the upper cam cover, which if it's the earlier metal type also needs unbolting. It's held on with 2 10mm nuts on the cam cover and an allen head fixing at the bottom of the upper cover, halfway down the side of the engine.

[GT_II]

the allen head pivot bolt for the alternator itself, this behind the upper cam cover, which if it's the earlier metal type also needs unbolting. It's held on with 2 10mm nuts on the cam cover and an allen head fixing at the bottom of the upper cover, halfway down the side of the engine.

From memory, with the later plastic type cambelt cover, the allen headed alternator mounting screw is accessible through an access hole in the cover, so the cover can be left in situ.

If yours has the later tension arm incorporating a geared adjusting bolt, the correct tension on the belt is obtained by turning the geared bolt to tension the belt to a given torque setting (the Haynes manual should hopefully give this figure), then tightening the lock nut to hold the tension at this point.

[GT_II]

From the factory workshop manuals, for the rack and pinion type alternator bracket, the adjuster screw should be tensioned to 8 Nm, then the lock nut tightened to 35 Nm to hold this tension. The screws in the engine block should be tightened to 20 Nm. The manual advises starting the engine and letting it idle for 5 minutes. Then loosen the adjuster lock nut again and reset the belt tension with the adjuster screw to 8 Nm, then secure in this position again by tightening the lock nut to 35 Nm.

For the older non-geared bracket, the belt tension should be checked manually to give 2mm slack when pressed with thumb between the pulleys on a new belt, or 5mm slack on a used belt.

[rosie]

Thanks everyone!
I’ve had partial success. The teeth on the adjusting nut and on the bar are rounded off. I ordered a new toothed nut. Couldn’t find a replacement bar though.
As a result I’m not 100% that it’s tight enough as it’s not holding in the correct position. My torque wrench is the wrong size to fit a 13mm nut so I couldn’t be sure that the locking nut is tightened sufficiently either.
I can twist the belt round to 90*, and maybe a little bit further, which I think means it’s a bit on the loose side.
The battery light’s not coming on though, so it’s not a disaster.

I found a couple of videos on YouTube of Mk1 Golf alternator belt replacements which were the same set up, in case anyone else is as clueless as me and needs pointing in the right direction.

[mark1gls]

Yes the nut often rounds off because someone has not loosened the bottom bolt and bolt attached to the bar and forced the nut round.

It’s the cam belt which you need to twist through 90 degrees, the alternator belt tension is 1/2 way along it’s longest length with your index finger it’s should deflect 10 - 15mm

If it’s to lose you will near it squeal when starting the engine and it’s running for about 30 seconds.

You will need to check and possible re tighten the belt after about 500 miles as they do stretch.