We replaced the starboard riser gasket, torqued to proper specs. We then ran a water test with the hose, pressurizing both the exhaust cooling and engine coolant systems, all spark plugs removed and ran water for 5 minutes without cracking engine. No evidence of water from spark plug holes. Cranked engine many times, several times and saw no evidence of water coming from spark plug holes. Shut down water and proceeded with “wet” testing our cold cylinders. We several squirts of oil in each cylinder and then cranked the engine to blow out any excess. Then we tested each. Then we put in new spark plugs and connected fuel pump and everything to run the engine. Engine cranked a couple times and then started right up, sounding very good. Let it run for 15-20 minutes, temp came up to normal and stayed. Revved the engine several times and it sounded really good. No exhaust smoke. Shut down and waited for 10 minutes for it to cool enough to remove spark plugs. Then performed the compression test for each cylinder in a “hot” state. Got really decent compression out of all except one cylinder, that had previously tested good in a cold and wet states. Then we meticulously ran the leak down test on each cylinder and there too, got pretty good results. All cylinders in the green. Strange given that one cylinder consistently tested zero on a cold cylinder. Got better when wet and even better when hot. And another cylinder started out looking good but got worse when hot but still had good leak down results. All our compression results are in the attached PDF.
Anyway, at that point we put the plugs back in and ran it for another short while with the hose pumping water. We started and stopped a few times and it really seemed “back to normal”, but it has sounded normal to us before when sitting in the driveway but had loss of power when under load, so we figured, even through our compression results were kind of all over the place, we still had compression in all cylinders and the engine seemed to run and sound great. We thought putting it back in the water would be the next best test we could run. I think we feel that if we blew a head gasket such that water was still getting into the cylinders, we would have seen that water during our water test or after we ran it and did our hot compression tests. We also felt that if we blew a head gasket or was cracked such that we had sever loss of compression, we would have seen that in the compression test. We are sure our valves and/or rings may have some corrosion or other wear but we never found a completely dead cylinder. If we still have no power or experience hard starts or anything, it will most likely lead us back to removing the heads examining the cylinder walls and pistons etc.
