Overheating!
Ever since its first outing my Bug engine had a tendency to boil, leading to numerous engine flushes and the odd expletive. At one time I thought it was the water pump, in went the second radiator, the 73° thermostat, but the problem persisted. The only way I could keep the engine from overheating was to keep the revs below 3000.

I took off the cylinder head, water pump and rear core plug, this gace access to all the water ways. Poking a copper wire through from the water pump I was able to clear out the waterways behind the cylinders, number two was blocked. I then cleaned out the back of the block via the core plub. Replaced everything and the engibne now runs OK. - Problem solved.

Another solution suggested to me was to put a Calgon Tablet in the engine, run it for a few days, then flush the engine out. I haven't tried this myself yet/

I hope this tip helps others who are experiencing similar problems.