My '84 Vanagon has perpetual cooling system problems.  I've replace the
radiator, removed the thermostat, replaced the water pump, flushed air out
of the system, and checked for leaks but can find nothing wrong.  Seems
like there is not enough water flow.  Engine will be boiling hot but the
radiator will be cool (even without a thermostat).  Does anyone have any
ideas what could be wrong?

If I can't solve the cooling problem, I want to swap the engine and I don't
mind switching to the 2000cc Type 4 Air Cooled engine used from '78 - '83.
Could anyone please tell me which engines (other than the waterboxer) will
simply bolt into the existing motor mounts and transmission system (4 speed
manual)?  If the Air Cooled engine fits without major changes, I'm tempted
just to buy a rebuilt one for $1000 and slap that puppy in.

Thanks for any help.

Preston Lewis