I would add the $3 tank valve. pump it up to 10 lbs. See if it drops. If you have a compression tester you could take the hose & remove the schrader valve from it & screw it into each cyl with a balloon sealed on the quick disconnect end & see if it expands as you maintain the 10lbs. spray some soapy water around the freeze plugs & the drain plugs & sparinly on top of the intake manifold to head face(s), both sides and around the pump and pump housing & see if any area bubbles show. holler how it turns out. EDIT If you pump the cyls & if this is a new cam breakin I would undo the rocker arms so the valves are closed/cyl(s) sealed so you dont have to turn the dampener to get each cyl on TDC which will wipe the goop off of the lobes.