overheated

[engdockter]

I am trying to help a friend of mine who overheated his boat this past weekend,any of you out drive guys ever experiance this, I am sure its been done[98 chev big block brovo one] grounded boat on sand bar tried very hard to power it off to the extent it cracked the plastic water pump housing after replacing the impeller and housing started backflushing hoses to find both oil coolers completly cloged with sand, got all the sand out of coolers and hoses now comes the good part went to start engine locked up, pulled sperk plugs and cylinders are full of water [hydrolocked] being that their was water in cylinders I decided to pull risers, the exhast ports are full of sand and water. Question, do you think I can put a set of risers on it and be done or does he need an engine? Thanks for your replys in advance.Sorry ment to put this in engines fourm I will try to change it.

 

[j-d]

Sounds to me like some of the backflushing water wasn't restricted from the exhaust manifolds/risers and worked back into the cylinders through the exhaust valves. Trace all the cooling hoses and see if you agree.
IF that's what happened, my thought'd be to make sure the crankcase oil isn't full of water. Drain if it is and refill with new cheap oil/fiter. Then remove all spark plugs and crank engine to expel the water. Listen for odd noises. Do a compression test. Check and possibly drain/replace oil/filter again. If you've got good results (meaning you don't hear or find anything awful so far), try starting it.
Again IF all you did was work some fresh water into it, and you work it out again quickly, you just might get away with a couple oil/filter changes. If it still runs and runs OK, change and watch for any milkyness. When it's clean, run a couple hours and change again.
This of course hopes nothing bent when you cranked and hit the hydrolock.
Check the starter attaching bolts. If they're loose, cranking against water probably stretched them. Story about this on arcomarine.com Pull up the Catalog then Starter Tips. Stretched bolts could be a hint that something else also bent.

 

[jtybt15]

That very scenario is fairly common for lake boats. Used parts houses are filled with them.

As far as the engine, the only way to know if it salvageable would be to strip it down and inspect the bare block. Check for cracks and warpage. Cold water entering a hot engine can do that kind of damage. There are short cuts but it depends on the engine damage.

 

[engdockter]

I should have been a little more specific about backflushing actuly I just pushed the water back thru the intake hose and cleared the outdrive then the intake hose thru both coolers, after that I pushed water outward thru the risers just as the normal water flow would go I would not think that should enter the exhast valves with this procedure,correct me if I am wrong, and when you apply water there again it fills the cylinders with water, sounds like cracked or bad gaskets in risers but I am not that familiar with riser leaks.

 

[littlebookworm]

The long and short of it is that the engine possibly is toast, but may not be. Try jd's advice. If it works, count your blessings. If not, count it as a very expensive lesson learned. Sorry. Hy

 

[j-d]

If you pushed water into the risers, engine not running, that water probably reverted back down into the exhaust manifolds and the cylinders. I remain optimistic that since it was a recent development and involves fresh water, you may get away OK. Did you find water in all eight, or mostly the center ones on each side?
We towed a Baja with 454 that got into mud and the cooling system plugged up. Luckily we were at a state park camping marina. A sailboater there let us use his water hose and I backflushed from thermostat housing back throught the coolers, water pump and outdrive. Mud billowed out and we flushed till it stopped showing. Reinstalled hose and it ran fine. I didn't do any more than that and it was all I was comfortable doing. Guess I was right. No experience with Inboard or I/O then, we always had outboards.