[Clifford Pope]

I have so far been able only to obtain a replacement for the steering pump belt in the size 11.9mm, but it is a much better fit on the pulleys than the so-called Volvo correct 9.5 or 10 mm. Also it is quieter.

However, futher investigation of my stock of old alternators and water pumps shows that there are two different sizes of pulley, used, if my cars have been any judge, quite erratically by Volvo.

The picture shows the difference between two water pump pulleys. The grooves are quite clearly wider in one than the other. The same is true comparing spare alternators. In addition, the wider-with groove pulleys are about 1cm greater in diameter.

There are three consequences of this:

1) As several posters have reported, stock belts are often a poor fit in the grooves, causing a sqeaking noise.

2) Alignment of the components will be impossible. As the photo shows, pulleys with different groove widths cannot line up properly

3) Because of the different pulley diameters in use, the ratios will change if there is a mismatch. In particular, a larger crank pulley driving a smaller alternator pulley will cause the alternator to run at a higher speed.

So the conclusion must be that if you want properly aligned belts that don't squeak, you need to firstly establish the size of the crank pulley grooves on your engine, then acquire matching width pump and alternator pulleys.


It would be interesting to learn what other members find on their cars. Mine has wide crank, water pump and steering pulleys, but narrow alternator.