Mk1 VW LT 35 Tipper Truck 'Lloyd'...More Paint....

Is it routed wrong? doesn’t look like much engagement on the waterpump.... google says that’s right (though it was in Russian or something )

Is the timing out by a tooth then?

  It's all routed correctly and incredibly, it hasn't jumped a tooth. But, as austinpowers and yourself say, it is slack around the water pump.....but why? 

No......water pump is the correct one. It's a tricky one to spot...even I had to look twice. I'll give you a clue......there's something missing.

I know nothing about these, is there a tensioner/idler missing from above the bet in-between the big cog and the water pump cog (see zero technical terms lol)

Sorry mate......still not right.

The correct number of items are there.......there's just something missing from one of them. I shall reveal all a bit later. 
Yeah....once I realised what had happened, I found it unbelievable that the engine was still functional.....especially as at the time I'd just put 500 miles on it within that month.

I had similar issues with a Pinto motor about 20 years ago. Only it was a case of the belt riding forward. I replaced the belt twice ( both times unipart items ) then 3rd time using a Gates belt.......and it still rode forwards. Cut a long story short, it turned out to be the Rally Design ( if I remember rightly ) vernier pulley that was fitted. I changed it back to standard and never did it again.

I now know that the earlier ones only had the lower idler and the water pump was used to tension the belt.

But yours has the tensioner in the top idler... so unless that isn’t working I don’t know

But hopefully next weeks lockdown pub quiz will have questions on D24 cambelt arrangements, COD I’m going to kill it!!

Has the idler belt wheel come off leaving just the bearing reducing the overall diameter ?