I posted in the general section but based on advice I recieved it does look like I did major damage which I plan to dig into myself.

For background, I was running my 92 26' Sleekcraft (with 454 non mag and Bravo1) for about 10 minutes today. Was running fine and then all of a sudden it lost power and 5 seconds later stalled. I tried to restart and noticed the engine was turning over slow - I looked at the temp gauge and noticed it at 180 but the red area is between 220 and 240. I opened the hatch and heard lots of crackling (like a motor sounds if overheated) and the top manifolds were very hot. I towed it back to my dock and then about 30 minutes later tried to fire it up - no difference - still very slow to turn (about 1 rotation per second or 2) and did not fire up. I then removed the spark plugs and on the positive side there was no water on the plugs - I then tried to turn over the engine (without plugs) and it still was very slow to turn over but on the positive no sign of water coming out the spark plug holes. I then got my compression tester and started to test the left side (facing back) and found all 4 with zero'ish compression except the 3rd one - but to be fair the engine was turning over so slow that I'm not sure if the compression was accurate. I only got around to doing the left side cause after each cylinder test the engine would get slower and slower and eventually after the 4th one the engine would no longer turn. Yes, I did test my 2 batteries and they are 100%. I towed it back to the launch and brought it home - on the muffs tried one more time to turn over and now it is turning again but still very slow.

The POS boat is really a POS. 2 years ago I blew and headgasket and a head - I replaced both heads and gaskets. A few years ago I replaced the gimbal bearing, and now again only a few weeks ago I again had to replace the gimbal bearing as it blew apart due to a tear in the bellows. Just fixed everything up a few weeks ago and now this.

Anyways, need advice where to start. Would removing the intake show me anything, or should I remove the heads too? What should I look for? Why is the engine so hard to turn over? Should I spray some type of fluid into the cylinders with the plugs removed and try again? Any advice where to start would be appreciated.

Thanks

^^^^^^^^^^^^^^^ yea what he said is probably right.if you dont want to pull it right away you could pull the plugs,rocker arms and push rods,try to hand turn it over with a breaker bar and socket on the crank.if its still hard to turn its
got to be in the bottom end.

Pull your outdrive and try again.

I can do that, but just want to understand why/what that would do? If I overheated the engine and it is slow to crank, why would the outdrive have any affect? I did just recently replace the gimbal bearing - could that somehow caused my engine to overheat and now be slow to crank?

Thanks

And while the engine is out replace the gimble assembly.

I just went and checked a few things. First I tested if the prop spins freely when in neutral and it did - I then put it into forward and confirmed the prop only spun one direction and locked on the other and then in reverse confirmed same except spun in opposite direction - so based on how the prop is spinning freely I doubt the drive is causing any issue.

I then went to try to turn over the engine - still slow but turning. So I went to try the compression on the right side and was only able to get 3 of them done since eventualy (again) the engine was getting slower and slower until almost no turning. On the right side, the farthest cylinder had minimal compression (around 60) but the other 2 (coming closer to front) had zero. And as my earlier post stated, on the left side 3 of the 4 had zero - so most of the cylinders have zero compression - what does that mean???? Can a really bad head gasket cause virtually all the cylinders to have zero compression???? I find that hard to believe. Plus the gasket wouldn't cause the engine to crank slow.

Need advice on my next steps? My plan is to remove the manifold and risers and then carb, ignition and intake. Once these all off can I still use the starter to try and turn the motor over to see what is going on - is this possible? Or should I also remove the rocker arms and rods and then the heads - if I do what should I look for? And same dumb question - can I use the starter to crank the engine when the heads are off to see what is going on?

Thanks