Mach2
06-29-2003, 10:42 PM
OK, had the boat out 4 weeks ago and it ran OK. It was down a few hunder RPM (5700 vs. 6000-6200) but it also had year old gas in it and it was warm. Hence thought nothing of it.
Last weekend I took it out. It idled fine and pulled out of the hole OK, but could not go over 5200 rpm. Pulled all the plugs for a compression check and water came out of the bottom port plug hole. Crap, blown gasket. For kicks did a compression check, 5 cylinders between 110 and 115 PSI (stock motor-650 hours on it). Last cylinder was 80 psi. Also performed a leakdown test. First 5 cylinders were less than 4%. could not measure the last because you could hear air escaping. Pulled the head and found a leak in the gasket.
Checked the cylinder bores. The good cyclinders all look get, no wear marks or carbon build up. The blown cylinder also has no carbon build up, but it shows signs of scouring. If I were to describe the scouring, it is between the 6-8 o'clock position, heaviest closer to the ports and almost none TDC. I tried to feel it with my hand and could detect no ridges, also tried with finger nail but no ridges. There is no rust in the bore (these are chrome sleeves).
My question is, should I worry about the scouring or just let it go. I am taking the boat out this week-end so a teardown right now is out of te question, but could happen later this year. Sorry for the long post but wanted to give plenty of detail.:confused:
Last weekend I took it out. It idled fine and pulled out of the hole OK, but could not go over 5200 rpm. Pulled all the plugs for a compression check and water came out of the bottom port plug hole. Crap, blown gasket. For kicks did a compression check, 5 cylinders between 110 and 115 PSI (stock motor-650 hours on it). Last cylinder was 80 psi. Also performed a leakdown test. First 5 cylinders were less than 4%. could not measure the last because you could hear air escaping. Pulled the head and found a leak in the gasket.
Checked the cylinder bores. The good cyclinders all look get, no wear marks or carbon build up. The blown cylinder also has no carbon build up, but it shows signs of scouring. If I were to describe the scouring, it is between the 6-8 o'clock position, heaviest closer to the ports and almost none TDC. I tried to feel it with my hand and could detect no ridges, also tried with finger nail but no ridges. There is no rust in the bore (these are chrome sleeves).
My question is, should I worry about the scouring or just let it go. I am taking the boat out this week-end so a teardown right now is out of te question, but could happen later this year. Sorry for the long post but wanted to give plenty of detail.:confused: