While running down the St Mary's River with a boat full of College Students from a Friend's church, my engine suddenly changed tone and then seized. Mark was there with his Grandsport to take my passengers and give me a tow. I thought it had overheated and seized up but I tried to get it to spin over after a few miles of being towed.
To my surprise it restarted and I was able to limp the last 15 miles back to the ramp but it would only turn 5K RPM and not idle. When I got home I pulled the Jaye Smith heads off and found that #6 had scuffed and popped a small part of the piston top off. I sent a picture of it to a Friend who is a Black-Belt and he immediately diagnosed it as water intrusion. I then examined the 2 year old Merc OEM head gaskets and found there was erosion of the metal head gasket between the water jacket above #6 that allowed a small spray of water onto the cylinder wall of #6. My engine does see some salt water use but always [afterward] I back it into a fresh water ramp and run it on the trailer to flush it out. The heads were still torqued properly but the gasket metal ring still eroded enough to wash the oil off the cylinder wall. The other 5 cylinders are pristine and still have their crosshatch after more than 600 hard hours [the Pennzoil XRF oil/oil injection is working well with absolutely no carbon].
From what I understand this is not uncommon.....I had it happen on my 1976 Johnson 200/Hydrostream Vampire after just 3 years old and wiped the motor.
To my surprise it restarted and I was able to limp the last 15 miles back to the ramp but it would only turn 5K RPM and not idle. When I got home I pulled the Jaye Smith heads off and found that #6 had scuffed and popped a small part of the piston top off. I sent a picture of it to a Friend who is a Black-Belt and he immediately diagnosed it as water intrusion. I then examined the 2 year old Merc OEM head gaskets and found there was erosion of the metal head gasket between the water jacket above #6 that allowed a small spray of water onto the cylinder wall of #6. My engine does see some salt water use but always [afterward] I back it into a fresh water ramp and run it on the trailer to flush it out. The heads were still torqued properly but the gasket metal ring still eroded enough to wash the oil off the cylinder wall. The other 5 cylinders are pristine and still have their crosshatch after more than 600 hard hours [the Pennzoil XRF oil/oil injection is working well with absolutely no carbon].
From what I understand this is not uncommon.....I had it happen on my 1976 Johnson 200/Hydrostream Vampire after just 3 years old and wiped the motor.
