I have been twisting wrenches for over 60 years and opened 1,000s of radiator caps. This one on my newly acquired boat will twist so far and then I can push it down and go a little farther, so far it is normal, but then it will not come out of the manifold. It has been years since the cap was removed and I suspect the rubber is stuck on the manifold or radiator neck. I don't want to pull the cap apart. May try squirting some WD40 in there to loosen it up. Any other suggestions?
I also have a couple of other threads going on the alternator
and fuel injector pump
and appreciate all the help so far. Will head
out to where the boat is docked and try something soon.