I’m liking the washer as a spacer idea. So this would solve the issue if the pinion is going in too far. But even if the pinion did go in too far, I don’t understand how would this prevent it disengaging ?
As a first step, check your new wiring. With the engine running/howling, check there isn’t still 12V on the solenoid connection. If there is, the starter will stay engaged. As a test, get the engine going and yank the lead off the solenoid.
I definitely would not space the starter motor with washers. The motor is a Denso unit with an adapter specific for the VW application. Your motor is the same as mine and was manufactured in the same batch (about 2 months ago) and is from the same supplier, it should not need any spacers. To check it disengages turn the engine by hand at the pulley and have someone feel if the starter motor is rotating, if the motor is still engaged the engine will be very hard to turn. Another check – remove the motor and operate the ignition/starter switch, the solenoid should push the pinion out; release the starter switch and the pinion should retract to the original position. You can easily measure whether the pinion retracts sufficiently to disengage the ring gear, if it doesn’t it’s faulty. Are you sure the starter relay is wired correctly and only energises when the switch is in the start position?
@Little Nellie Do what snotty said but if the starter motor isn’t disengaging don’t run the engine very long or your nice new starter motor will be fubar.
I think I understand what’s happening now. I unslackened both nuts and when you slide the motor across the face of the bell housing it pushes back anti-clockwise. From here I slide the motor out (so effectively starting to remove it) and suddenly it frees. This is a 2mm distance So this must be the pinion still engaged when retracted - about 2mm. I would expect spacers would sort this but not advised from above. They’d certainly prove the point for one spin of the engine? Saturn has boffed right in my face again
I don’t remember if you’ve said which gearbox/bell housing you have. If it’s pre August 1975 you have the wrong starter motor – should be a RAC525. https://www.coolairvw.co.uk/product/ac911rac525/
Yep just seen that 311 911 023 is up to 1975! 091 911 023 is the 1979! so I’ve got a upto 1975 bell housing according to that old starter motor. Oh CARP I’d have never have guessed that. All engine stuff has been 1979 carp
It does look like you have the wrong gearbox/bell-housing and consequently the wrong starter motor. How many ribs on the top of the gearbox? It should be 6-rib box for a ’79 bus.
Blinking ek. It’s a mile out! photo below shows the caliper set at the distance set from the old Bosch motor. So mating face to end of pinion distance Bosch distance is 32.5mm the powerlite is 42mm. Need a few washers there I hope coolair will accept a return. My fault of course, but I wouldn’t have expected 1975 bell housing
You can see the marks on the teeth in your picture where it was spinning engaged with the engine running. At least it remained engaged rather than chewing off the end of the pinion or damaging the flywheel. My shimming experiment comment was assuming it was aftermarket manufacturing tolerance rather than a totally different fitment.
Did they carry on fitting 3 rib gearboxes to T1 1600CC engined buses later than 1975 ? I had a 1979 T1 engine with an original flywheel machined and drilled for a 200mm clutch on it, so maybe VW did change over gearbox style as well, although they must have kept the gear ratios about the same as before, as it would not have gone well for the engine with the different gearing. Just asking.
