Fan belt problems

[Psucamper]

My 79 2.0 FI engine has begun to flip the fan to alternator drive belt. The belt dislodges itself from the V grooves. If I sight along the belt it is evident that the two pulleys are not co-planar. Measuring the displacement is difficult but a straight edge along the outer two pulley edges shows that the alternator pulley is too far out by about 3.5mm. This measurement may not be the actual V to V displacement. I will try to be more precise with the next measurements

Two possibilities to remedy the problem are to shim the fan assembly out 3.5mm or to mill off material on the rear boss on the alternator pulley by 3.5mm. It should never be necessary to do either. The whole structure is solid and locked down so as to not need to go to such extremes. I find no play in the alternator mounting and no wobble in either the fan or the alt pulleys.
Unfortunately, this car has not been on the road for a while so I have no pertinent history of its past behavior. It does have a new belt installed.
What have I missed? Any thoughts are appreciated.

[Bleyseng]

Is it the correct alt? What about the pulley? Is it on all the way or is it installed so the "key" is stopping it from seating correctly?
This is a no brainer situation if all the parts are VW and correct for a type 4 as they are all the same except for the 70amp alts which are different animals.

[airkooledchris]

did your bus come with AC originally? I know on one of mine it had AC, so the fan mounts up with a spacer where there is no spacer on the other one.

I could be wrong here, but it's worth a look in the manual/software parts diagram to see if your missing something that would be pushing the fan out a bit further.

[Psucamper]

To all who responded to my plea for help..thank you. It was a faulty flux capacitor . Er.....it was another dumb ass mistake by me! Operator error. The boss on the alternator pulley faces OUT not IN towards the alternator body. Doesn't look like that's the way it ought to go but it is. Pulleys are now co-planar (very close) and the alternator hums happily. On to an intermittent start-up problem.

[Amskeptic]

did your bus come with AC originally? I know on one of mine it had AC, so the fan mounts up with a spacer where there is no spacer on the other one.

Spacer on non-A/C buses . . .
Pulley on A/C buses . . .

When you leave either one out, the alternator belt is the least of your worries as the fan bolts tear the rear seal right off.
Colin