What happened??? blowed engine

[DWD]

I was running down lake, good water pressure, no bells or alarms or noise. Boat ran great last time out. Then it happened.
I saw the piece of rod cap in the cowl it was blue in color indicated to me no oil. Blew on Sat. torn down on Sunday, seen all rust in no. 1 and 2 cyl. Thinking head gasket blowed on #1 side but when I pulled the head over #2 cyl found rust also. Anybody got a clue to what happened. Dont understand all the rust and damage on head gaskets. I also run Mercury Prem. blend and 89 oct. gas '99 200 hp Mariner. Thanks for you help

[pyro]

Push the little button on your camera with the "flower pot" icon before you shoot a close-up photo. It will come out in perfect focus.

Sorry to hear about your luck...

[Eagle One]

Looks like you had a blown head gasket prior to or at about the same time you ran it Saturday. The exhaust gas pushed out into the water passage making the engine appear to have good water pressure as steam will produce more pressure. The rust is due to the engine sitting over night and the heat creating a good enviroment for rust to form before you tore it down, especially if it was in salt water. You could have had a connecting rod go out that caused the piston to slap the head resulting in lifting it enough to blow the gasket. You need to run a temp gauge with a water pressure gauge as this can happen in a matter of seconds. Hard running even as low as 4000-5000 RPM can do it in just a couple of minutes or even less.

[DWD]

Thank you for your reply that helps confirm what I was thinking. What kind of temp gauge and where do you put it? I have a water pressure gauge.

[props4u2]

You can usually detect a blown head gasket pretty quick as your water psi usually pegs your water psi gauge due to compression entering your water jacket. The blown head gasket could have happened due to old/brittle head gaskets if they are original. It could have been leaking for a while and rusted or pitted the crankshaft and caused the rod bearing to fail.



Lee