OMC 800 overheat, stall, no start

[atx111]

Ok, even though I got rid of the boat, this has been driving me crazy for the last couple of weeks, and sorry this is so long. My '78 Cobalt with a Ford 351 and 800 Stringer drive was running great(of course) until we were cruising along and the engine started to sputter and lose power. I immediately checked the temp gauge and it was past 240 degrees( I had only looked at it 30 seconds before and it was fine). Before I had a chance to do anything, it stalled out on me. Opened the engine compartment, it was hot, smelled hot, and couldnt even think about touching anything.

After letting it cool overnight, I went to at least see if I could get it started. It would crank over fine, but not start, and it would backfire through the carb when I was cranking it. Went and grabbed a mechanic at the marina just to see what he thought. I told him what had happened, and after about 20 minutes he got it started. It ran horribly for about 20 seconds then dies again The mechanic checked and said ignition system was gone. I knew that whatever was going on, I knew wasn't good even with my limited knowledge of marine engines.

The impeller was replaced last fall with winterization and it never ran hot up until that point. We ended up deciding to ditch that boat for a new one, reasons being that I didn't want to potentially spend alot more money on an old boat than I already have, especially one with an obsolete drive that would cost a small fortune to fix unless I knew how to do it( I don't) and had a source of used parts(I don't). I'm not bashing Stringers at all, I just wasn't interested in the potential headache it could bring.

My question is, then, even though I didn't want to mess with it at the time, what are the best and worse case scenarios for the potential damage to the engine that occurred when it overheated. I know its a moot point now, but its just for my knowledge. Thanks!

 

[wire2]

Re: OMC 800 overheat, stall, no start

A bad overheat can/will distort heads. Then the head gasket will fail, allowing water and compression flow between cylinders 3-5, 4-6. Hard starting, very rough running. Probably water in the middle 4 cylinders. Check the plugs.

A lot of weeds around the leg will stop the water coming in, engine overheats.

To quickly test the impeller, put muffs on or connect a hose to the trunnion cap fitting. Remove the coolant water hose at the thermostat housing, observe the flow volume. Now start the engine; did it remain the same, or considerably more flow?

 

[atx111]

Re: OMC 800 overheat, stall, no start

Thanks for the reply. So what I gather from your post could lead to a pricey rebuild or replace. My thought from the start was I sucked up a bag.

 

[wire2]

Re: OMC 800 overheat, stall, no start

Have a look at the plugs, then try a compression test.
Warped heads can be milled at any engine shop, is not very expensive.
I went through this 1 time.