Rebuilt engine approx 4K miles ago - for the last 2K miles I get a fair bit
of dampness and dried salt around the top of the overflow bottle - tunrs out
hat if I rev the engine, & hold it - no problems. If I then let the revs
drop back to idle - I get a 'burb' of gas coming via the metal expansion
tank cap to the oerflow tank.  It's a puzzle, if it was a leaking head
gasket I'd expect bubbles as I rev the engine - but I only get them when the
engoine returs to idle....

any thoughts out there....

steve