This is an old engine that I was working on to get the exhaust seat ground and the valve lapped. Well I got back to it and thought I had valve fixed since I got good results with leak test on bench. Put it on mower and it wouldn't start. Well put leak tester back on leaking out of the oil dip stick. Now what the hell is going on? When the unit was on bench it was not leaking. I put compression tester on and it was in 50 range...but I am more interested in how can you get a good check on those valves if air can get past the rings?