fan belt problem

[bmw2101]

i have a problem with my b230 engine, i have converted back to a V belt its a 935x10mm belt i think. I have had the bottom pulley made, but when i put it on the water pump pulley seemed to be 3-4mm out, so i placked that out with some spacers. Now its pulled the belt in about 50 miles. why could the top pulley be out, or what have i done wrong? thanks

[Steve]

I don´t know what you did wrong, but is the alternator flexing?

[bmw2101]

the alti is on harder bushing, when it had a flat belt on it the bushes went, ill have a look at them tomorrow actually see if they are broken again and that is the problem.

[fulsnut]

And the water pump pulley doesn't flex?

Everything lines up?

[bmw2101]

so i have fitted new belts and looked closely. The bottom engine pulley looks the same as the alternator pulley, but the top pulley on the water pump, the belts seem to be 2-3mm closer together. Is there 2 types of pulleys? ive only bought these parts and put them together on this engine, so some could be early parts and some later ones for example.