OK so after walking away 11 days ago – its time to investigate the problem again. Dad my mate Ian and I look at the car its lost fluid while standing so we get a lead light and stare. Ian then spots tiny bubbles from where the new water pump meets the block, looks like there is an issue there.
The water is leaking out the pump seal and dripping out the bottom of the lower cambelt cover, and crucially over the back of the top of the pump making it fall on the thermostat housing. Further investigation proves the pattern water pump we fitted has pre-drilled holes to go on two locating dowels in the block. These holes are just too small preventing the dowel pulling through by a 0.5mm or so causing a gap and the seal to blow. Putting the old pump and seal back in place (these didn’t look too bad at all) and it fits much better so we’ll leave it for a few days and see what happens.