Engine overheated, funny sounds, now it won't turn

Took the boat out for 4th of July fireworks...didn't even the notice the temp read over 240 until it was too late...

Shut the engine off but there was some funny sounds going on in the engine compartment even though the engine was off. Tried to fire the engine up again but now it won't turn over at all. I wasn't even able to flush it since it was in salt water

What did I screw up? The impellar was less than 20 hours. I think the impellar disinegrated and went into the engine.

What are the steps to troubleshoot this problem? I am planning to check the impellar tomorrow but after that what should I do? I am afraid I fried the engine...

Please help...thx

Your not going to like this but I suspect its seized.

If its not turning then check all the leads on the starter. Next pull all the plugs so the engine has less resistance and try it.

If still no go try to turn it over manually with a big breaker bar on the front pulley.

If still no joy then find a mechanic and bend over

Yup do like Jay said, remove all plugs and try to turn with big breaker bar, if it won't budge drop a little transmission fluid in each cylinder to act as lube, and let it sit for a minute, then try to turn it, maybe you'll get lucky and it will turn, if not, you sir have seized the engine.

Im just curious Wilson, does your boat have a buzzer/beeper to warn you of low oil press/trans press/high temp??
Oh yea you seized it but with alot of luck youll get it unstuck and it may run ok for quite a while. My brother in law drove his truck around for a day or two with a rod knock after dumping all the oil out and it shutting down on the side of the road. He fried all the crank bearings, put new ones in and i think its still running fine couple years later. It sounded horrible when he brought it by my work. I told him he shouldnt be driving it at all, he drove it home.

Yea, its probably seized. Turning it over by hand, if possible, is easier on the welded rings. The starter tends to shatter them. I have also used a spray can of light-weight oil. It is easier to get the oil all around the inside of each cylinder.
Even if it does free up, it will probably start burning a lot of oil. Good luck.

Just an update....

Checked the oil and no water or sludge but was ta bit dark for my liking. No metal shavings...whew...

I pulled the plugs and they were nice and dry and looked fine, fired the engine up and no water...whew...

Pulled the impellar off and it was mangled...

Replaced the impellar and backflushed as many hoses as I could find...saw a bunch of impellar pieces.

Charged my battery and....the engine fired right up and the temp has stayed at 160 F

Did I dodge a bullet here?

I will be changing the oil out and see if it will stay clean.

My theory is that I must have sucked up something that destroyed the impellar, the pieces then went into the engine which is what I heard.

I still have some concerns if I got all the impellar pieces or if they are lodged in the engine, how can I get it all out?

Are there long term problems I can resolve now because my temp was over 240 F for a long time... probably at least 15 minutes.

By the way, I am supposed to have a buzzer that sounds when the temp is high, it didn't go off. Another question.

thx for the help

you might have dodged it, keep an eye on the oil and change it if you haven't already. check all of your hoses, the ones from the exhaust are probably shot. if they have soft spots, replace em.

do you have a sea strainer on your water intake?

Will be changing the oil today.

There is a brass strainer but the gaps are wide to suck as much water in to cool the engine.

I am looking for a screen to install after the impellar line to catch impellar pieces when they dissenegrate.

Any idea where and how to install?

If your engine was making some funny noises you should probably check the compression to verify the valves are seating and not burnt.

I think they were parts of the impellar running through the engine. Is there a way to check for pieces in the engine?

Can you give me steps to check the compression? Do you just pull one plug out, install compression gauge, fire up engine, record reading and perform for all cylinders.

pretty much except you don't want it to start. i pull all the plugs first (or you can ground the distributor but, you don't want it starting) and then check each cylinder. once the gauge is in, hit the starter for about 5 revolutions...you'll see the gauge jump each time that cylinder comes around. after 5 or so spins it shouldn't go any higher, record the number. repeat 7 times on the rest of them.

ideally, your numbers will be above 100 and none will be more than 10% higher or lower than the others.

i've seen pics on here by someone who put a sea strainer after the impeller to catch any future pieces.

Wilson:

There are two common failures related to overheating:
1) the rings can sieze, which pretty much messes up the engine right away. If the compression checks out okay or even if the boat runs okay afteward then this probably didn't happen.

2) The heads can warp or crack: Depending on how bad it is cracked or warped it may or may not be obvious that there is a problem. If it warps bad enough the head gasket will fail and then you won't have compression in one or more cylinders. The gasket may not fail right away, however, so this could pop up some time later.

If the head is cracked then it may not show up on a compression test at all but it may suffer from overheating, oil/water contamination, vacuum leaks, etc.

The compression test is certainly a good idea and doesn't take too long. If that checks out okay then take the boat to a lake and try it out. If it runs okay, temperature is okay, oil is okay aftewards etc. then relax. If there are any problems then better plan on some major repair work.