E34 518i 1996 belt issue

[jamie325isport]

Hi I recently got myself a 518i 96. Previous owner had broken two of the three bolts that holds the thermostat. I fixed that easy enough and replaced with a new one.

Also replaced the water pump because of a rattle I heard and it had a bit of play.

With all this done there was still a rattle coming from the front which turned out to be the tension wheel/shock bouncing up and down (the belt was also jumping off the back of the alternator), so I replaced little tensioner shock.

So no rattle now all very good, but the belt is still jumping off the back of the alternator pullie. Not good. Ive checked and double checked the belt is on all the pullies ok. From the water pump down to the crankshaft looks straight and ok as it does from crankshaft to PAS and PAS to alternator but from the water pump over to the alternator you can see its pissed? Its like the waterpump pullie is sat to far back?

Im going to check the new pump shaft length to the old one to see if its shorter. Other than that Im a bit lost on what Ive managed to do wrong. All parts were from gsf. Thermostat, waterpump, tensioner shock, belt.

Just to recap before I replaced the water pump although it rattled from the tensioner it never threw the belt off the back of the alternator. Car runs perfectly except for this. Can anyone think of anything?

Thanks everyone.