Hey all,
Before I get to the issue, I will give you a little history of the motor. I bought a boat for a steal with a blown 1995 90hp. The previous owner had the head pulled already and you could see that the bottom piston had a nick in it where a ring got caught on a port. The pistons moved freely in the cylinders and came apart easily. All bearings were in tact and looked like they were in good shape. I rebuilt the powerhead this past winter; 0.010" over pistons, all new powerhead gaskets, all new bearings, rebuilt carbs, rebuilt fuel pump, new thermostat and new impeller. The motor went back together smooth, started and idled great. The first time I took it out for break-in, it got hot enough to trip the temp alarm and I shut it down right away. I found that I had a misfire on the first cylinder which I suspect wasn't letting the thermostat get hot enough to open. I traced that back to a bad coil pack and changed all 3. The temperature on all 3 cylinders now seems very close to each other and the thermostat opens as it should.
I then found that I have water in the 3rd cylinder from somewhere. I am getting a frothy/milky mess on that spark plug. A normal shut down from idle is not as bad as when I shut down from higher speeds (all of this testing is running the engine in a drum with water). My original exhaust plate was pretty warped and after some searching here, I decided to change that and the two gaskets again. After this did not fix the problem, I changed the head gasket with no change. While the head was off, I pressurized the head with some air and put a soapy solution on the combustion side of the head and noticed no leaks.
Today I took the reed valves out to inspect and everything looks good. I even swapped #2 and #3 reed valves as a check and it did not change anything. When the reeds were out I could see some of that frothy/milky oil on the reed for #3 and along the bottom of the block surrounding the lower bearing. I am not really sure where else to check. My last thought is to pull the powerhead again and check the base gasket.
One thing to note is that my rebuild kit did not come with gasket to go between the powerhead adapter and the motor leg. I used permatex ultra black on all mating surfaces. Do you think I could be getting water in the exhaust port from this sealing surface? Is there any way to check for a crack in the block without taking it apart and sending the block for magnafluxing? I did not see anything obvious throughout all of this and I looked pretty close.
I appreciate any help you guys can give!
Mike
Before I get to the issue, I will give you a little history of the motor. I bought a boat for a steal with a blown 1995 90hp. The previous owner had the head pulled already and you could see that the bottom piston had a nick in it where a ring got caught on a port. The pistons moved freely in the cylinders and came apart easily. All bearings were in tact and looked like they were in good shape. I rebuilt the powerhead this past winter; 0.010" over pistons, all new powerhead gaskets, all new bearings, rebuilt carbs, rebuilt fuel pump, new thermostat and new impeller. The motor went back together smooth, started and idled great. The first time I took it out for break-in, it got hot enough to trip the temp alarm and I shut it down right away. I found that I had a misfire on the first cylinder which I suspect wasn't letting the thermostat get hot enough to open. I traced that back to a bad coil pack and changed all 3. The temperature on all 3 cylinders now seems very close to each other and the thermostat opens as it should.
I then found that I have water in the 3rd cylinder from somewhere. I am getting a frothy/milky mess on that spark plug. A normal shut down from idle is not as bad as when I shut down from higher speeds (all of this testing is running the engine in a drum with water). My original exhaust plate was pretty warped and after some searching here, I decided to change that and the two gaskets again. After this did not fix the problem, I changed the head gasket with no change. While the head was off, I pressurized the head with some air and put a soapy solution on the combustion side of the head and noticed no leaks.
Today I took the reed valves out to inspect and everything looks good. I even swapped #2 and #3 reed valves as a check and it did not change anything. When the reeds were out I could see some of that frothy/milky oil on the reed for #3 and along the bottom of the block surrounding the lower bearing. I am not really sure where else to check. My last thought is to pull the powerhead again and check the base gasket.
One thing to note is that my rebuild kit did not come with gasket to go between the powerhead adapter and the motor leg. I used permatex ultra black on all mating surfaces. Do you think I could be getting water in the exhaust port from this sealing surface? Is there any way to check for a crack in the block without taking it apart and sending the block for magnafluxing? I did not see anything obvious throughout all of this and I looked pretty close.
I appreciate any help you guys can give!
Mike
