>Hmm, then would not a radiator flush before starting the job, >running only plain water as the last step, help eliminate this? >With antifreeze etc after the job is done of course. Couldn't hurt. But would NOT help if the rings were stuck from varnish. I do the Kreen piston soak on ALL the valve jobs I do just in case. As a matter of fact I need to order another 5 Gal of the stuff right now!! Bruce Hevner