will reversion always cause water on top of heads? I am trying to disect a problem that is kicking everyone in the back side. thanks...

i just replaced riser gasket which was allowing water to go into cylinder and cause a miss in #7
if you are talking about valvetrain area i don't think so
you might have a cracked head also did you over heat it lately how many hrs are on engine?

2 hours on last motors, 4 hours on ones before them. Never a heat issue, two seperate guages said motors never got over 165 degrees while running, and even after shut off only to 175 - 180. Oil presure was also good, no issues there....

no water in oil, we were checking every 10 minutes or so....

here is the kicker, on BOTH the last two motors that went down I had a merc certifed tech with me, first was on a test/tune run, second was on a poker run and a different tech was just out for the day with me, so while I may not have been quick to spot a problem, both these guys knew part of the reason they were there is to help find problems before they became disasters. That plan did not work.

Check exhaust for water leaks. A friend of mine went through two seasons and 5 or 6 engines(I lost count) due to this. Beat the ballz off them on a dyno first and only lasted (at best) hours iin his boat. Replaced exhaust and been running all this season

can you send name and phone # in a PM???? I would really like to poke around his experience as we try to fix this problem. Thanks!!!

check all exhaut parts surfaces. They have to be all 100% straight, otherwise even with new gasket you may have water coming in. Get the metal part shaved.

Who's/what exhaust system brand did he have that caused the problems? Just curious, thanks. Mark

Dean, what is the same for all the engines you have fried? Water pump, exhaust, carb, oil filter, fuel pump, what else? Eliminate those that you are sure are not causing a problem. Then check them again.

Also, if you could, please post some good clear photos of the engines in the boat.

I will get recent photos today....

Yesterday pulled plugs, they look good, no signs of ignigtion or timming problems, no signs of piston metal on them, compression is good, but a horrible knock.....

So it sounds like lower end problem.... going back to GM this week for warranty claim, will have to see what happens from there....