Hydrolocking of my 4.3L

[glasskisser]

Help! I have had my engine hydrolock several times. It started last year after taking it from storage. After clearing the cylinders (it appears to ony get water in the rear right back piston) it work fine but did it again a week later. After clearing it again, it did not happen the rest of the season. However, when I took it out of storage this year it happened again. Once again, I cleared the piston only to have it happen again when I started it a week later. Now it seems to be fine. I changed the flappers last year. I did give the boat a thorough power wash after taking it from storage both years. I just seems odd that it occurs at the start of the season and does not happen again.
Any advice of comments would be great.

[jkh04200]

Does this motor have the center risers? If so change the gaskets and check the wall thickness on the risers. That is where 99% of the problems with water come from. The manifold normally stays full of water, unless you drain for the winter, but the water in the riser drains down. Then the rust starts. But, its not really rust because cast iron doesn't "rust". It does flake away. If the wall thicknesses of the riser look thinner or more eroded than the wall thickness of the manifold, replace them. Water reversion does not come from lake water. It comes from where the cooling water is introduced to the exhaust. ITs supposed the mix at the end of the elbow but if your gaskets are leaking, and they are notorious for it, the water is mixing in the manifold. The rear cylinders are always the ones that get the water in them.

[centerhill condor]

well, I had this problem once with a 454...my guess is you're running a little rich with some carbon acting as fuel when you turn off the ignition and the engine runs on...doesn't matter if its spinning forward or backward.
Also, check your ignition timing. Like I wrote it happened once and I advanced the timing and no more problem.
Good luck,
CC

[glasskisser]

Thanks! That sounds reasonable and relatively inexpensive to repair!