Engine overheated and seized up

[Bobo]

I just purchased an 84 Nautique, took it out for the first time, ran it for about 3 minutes at 25 MPH, looked down and the temperature gauge was at 260. I shut the engine off immediately, opened the engine box and there was black smoke and alot of heat.

Now it won't turn over at all.

We're going to remove the plugs and spray some oil in them and try to turn over by hand in the morning. I'm really just concerned with getting it running again at this point. If anyone has any other advice, suggestions or diagnosis, I would love to hear them. Only if it's good news of course ;-)

[Onevw2go]

RE: Engine overheated and seized up

i had something similar happen. don't panic! I was freaking when it happened to me, but chances are the motor 'Hydro-locked' simply put, when it got hot, then you shut it off, water back fed through the exhaust into the motor. once one cylinder fills with water(water doesn't compress) the motor wont turn. Best advise I can give is... Pull the plugs and replace them with new ones. Change the oil, and a little fogging oil in the cylinders won't hurt. Good luck.

[Bobo]

RE: Engine overheated and seized up

Thank you for the advice and glimmer of hope.

Did you figure out why it overheated in the first place?

[bchesley]

RE: Engine overheated and seized up

There are about a hundred ways one can over heat. Did you have alot of water in the bilge? If you were not pumping water to the motor you most likely fried you exhaust hoses. Start by checking all hoses and engine plugs, then check the colling components ie water circulating and fresh water pumps.

Brad

[Fredk]

RE: Engine overheated and seized up

Replace the water impeller! It is the most likely reason for the overheating in the first place. No water coming in to cool engine down = overheating.

[Bobo]

RE: Engine overheated and seized up

Replace the water impeller! It is the most likely reason for the overheating in the first place. No water coming in to cool engine down = overheating.

Yup, ordered one this morning from skidim. I'm worried that I caused the problem by starting the boat a few times in my garage. I never let it run for more than 5 seconds, but from what I've read that might be enough to cause some impeller damage. I'll find out this afternoon when I check it, hopefully that's it.

[Bobby]

I had this exact same thing happen to my old 84 MasterCraft. My advice is to throw some Marvel Mystery Oil in through the spark plug holes, get new plugs, change the impeller and all that stuff, then turn it by hand until it loosens up.

[Onevw2go]

my overheating prob was caused by a clogged water filter. sucked some sand into the intake and it clogged the wire mesh, so no water could get through. good luck with your boat, and let us know what the final diagnosis was/is. I would be curious what it cost$$ to get it up and running again if you don't mind posting that info when you get done. my cost was around 1700$ when all was said and done.

[Bobo]

Onevw2go was exactly right. We removed the plugs and water spilled out of a few of the cylinders.

So, we replaced the oil and cleaned up the plugs and it's turning over again. We haven't fired the engine yet, but it looks like everything is okay. We opened up the impeller housing and the impeller was completely chewed up. There wasn't a single blade left on it. So, I'm gonna head to West Marine in the morning and hopefully get a new one if they carry them there. Otherwise, I'll have to wait til Monday to get mine in the mail to really test it.

Thanks to everyone for their suggestions and help. I'll post again after I put it in the water and fire the engine.

[jthooker]

As Brad said, you most likely fried your exhaust hoses. Even if they don’t leak or even blow out the next time you run the boat there is a good chance that one or both of them will fail in the near future.

[darrel409]

I think you are going to want to get that motor started up as soon as you can, run it to burn off the water inside and change the oil again. Good Luck!!

[Bobo]

I think you are going to want to get that motor started up as soon as you can, run it to burn off the water inside and change the oil again. Good Luck!!

We ran the boat for about 4 hours today and everything looks good. It took awhile to get it started again, but once she was running she sounded great. Temperature stayed around 120 and we never saw any signs of any problems. I'm going to keep an eye on the exhaust hoses and probably replace them plus a couple other hoses over the winter.

[darrel409]

120 temp? are you running a t-stat?
4 hours sounds good but it needs to heat up more than 120 to dissapate the H20.