Overheats while Cruising

[Memmer99]

Took my boat out over the weekend and was cruising to the cove. I looked down and it was over 200 degrees. once I slowed down to idle speed and the engine started cooling off. The impeller is new so I'm thinking a stuck thermostat or maybe some crap in the inlet? Can you guys think of anything else to look for?

Thanks,

[Chuck Yager]

I imagine that you have already done this, but it seems like I remember hearing something about a loose hose being able to do that very thing.... I would look everything over and make sure that all the clamps are good and tight and that none of the hoses have any holes or kinks in them... Hope that gets you pointed in the right direction!

[tg0824SSVGG]

Did the old impeller have any missing parts? If so - sounds like one of them is stuck somewhere ...

[cadunkle]

If you have a raw water strainer check that. Also check your pickup under the boat, and the trans cooler. I've found some weeds and such in my trans cooler every fall when I winterize. If you get enough in there it will restrict flow and overheat at higher speed/load but not at idle and lower RPM. Not sure what type of thermostat housing the 351w uses, but my last boat with Chevy 350 had a rod with a ball and spring on each end restricting flow to the manifolds. This was junked up and didn't move freely, causing overheating. Also check your thermostat to be sure it's opening fully. You can pull it and boil in a pot of water, you will see whether it's working or not.

[Memmer99]

Last night I pulled the thermostat and it was all rusty so I went out and bought a new 180 degree thermostat from O'Riley. Thing is they look very different but it fits. Now I just need to make a new gasket and test it out.

@Chuck, I'll double check all the hoses thanks!

@TG, The old impeller was 2 years old and still looked new. I saved it just incase.

@cadunkle, I looked at the pickup and it is not clogged up but I have not taken any hoses off. I will check that tonight. thanks for the tip!

[wotan2525]

Squeeze the hoses coming in and out of your water pump. They should feel "hard" when the engine is running.

You may have put your waterpump housing back together upside down. This is a pretty common mistake. Much more common than a stuck thermostat (stuck closed, especially!)

[jsandy]

The 180 thermostat is WRONG for your boat. Take it back and order one from skidem. I had the same problem and a new MARINE thermostat fixed it.

[oldman]

I agree with jsandy, I run a 143 degree from skidim and my engine runs around 160 degrees give or take.

[Memmer99]

Thanks for everyones comments and help. Last night I found that the tranny cooler had a bunch of junk in it. I took it off and back flushed it and hooked it back up. I bet that's what the reall issue was. Anyway I'm going to West Marine today to pick up the correct thermostat. We're going camping this weekend so that will be the real test. Hopefully it doesn't overheat or it will be a extra long weekend.

[docdrs]

Thanks for everyones comments and help. Last night I found that the tranny cooler had a bunch of junk in it. I took it off and back flushed it and hooked it back up. I bet that's what the reall issue was. Anyway I'm going to West Marine today to pick up the correct thermostat. We're going camping this weekend so that will be the real test. Hopefully it doesn't overheat or it will be a extra long weekend.

you may want to get a strainer if you are picking up that much stuff

[Memmer99]

Doc,

I was thinking the same thing!