Idling = Hot engine Under power = Cool engine - HELP

[Cowboyup]

I took my boat out for the second time yesterday after I changed the impeller and the belts on the engine. I was sure I changed the impeller the right way and put it back exactly the way it came off. I replaced the o ring inside, the paper gasket, and lubed up the impeller with vaseline before I put it together.

The first time I took the boat out, there were no issues with the temp. However, this time taking it out, whenever I was sitting in the water at an idle for more than a couple of minutes, the engine would heat up close to 200F. But whenever I got back under way and raised the rpm's up a little, it cooled right back down to ~150F which is the normal temp for the boat when cruising around. I checked the water strainer and the water inlet on the bottom of the hull and there was nothing blocking either place. I took back off the impeller housing yesterday to see if maybe I fried the impeller somehow, but it was still intact in the impeller housing. While cruising around the lake yesterday, I did notice a slight squeaking noise coming from the engine compartment. Could this be the signs of a dying water pump??? Please help me out. Thanks in advance for all the great advice.

[Flux]

RE: Idling = Hot engine Under power = Cool engine - HELP

Hot at idle and fine at cruising speed sounds like impeller or a blockage in the line.

[bobchris]

RE: Idling = Hot engine Under power = Cool engine - HELP

make sure the belt's good and tight and that your base idle isn't to low

[TRBenj]

RE: Idling = Hot engine Under power = Cool engine - HELP

Also check to make sure your strainer is on tight. If its slightly loose you may be sucking some air, which would cause the exact symptoms you describe.

[jedgell]

RE: Idling = Hot engine Under power = Cool engine - HELP

I've been having basically the same problem. I checked the impeller and it was fine, strainer was fine. So I ended up replacing a bunch of the water hoses, hoping that there was a small leak somewhere that was letting air in. Mine would only heat up when starting the boat. As soon as I would give it gas, about 3,000 rpms, the boat would return to normal temp and stay there until I turned it off. I'm heading to the lake tonight, so I'll find out if it worked.

[chris]

RE: Idling = Hot engine Under power = Cool engine - HELP

The strainer is the most common for this. It might seem "fine" but as little as 1/8th of an inch turn is enough tightening to fix the problem.

[jedgell]

RE: Idling = Hot engine Under power = Cool engine - HELP

Well, my boat ran fine last night, no issues with the temp. I'd double check the strainer, and replace any water hoses that look suspicious (any cracking). I ended up replacing about 1/2 of the intake water lines.

[Cowboyup]

Thanks everybody. And thanks jedgell. I think I have the same problem as you did. I remember that on one of the lines connected to the impeller pump housing, there was some cracking going on. I will replace all and should be good to go. I have checked the strainer and everything else too just to be sure. Thanks again. I will let everybody know how things turn out this weekend.

[porkchop]

cowboyup, let me know if those suggestions helped fix your overheat problem. I had the exact same problem this weekend.
Thanks.

[Cowboyup]

It sure did!!! The small hose going from the impeller housing to the engine had a crack in it. Before I changed the impeller, it must have been plugged up just right, but when I took all that off to change out the impeller, I made it worse. I got some new hose, and BINGO, no more overheating while at idle. The boat is actually running cooler than it ever has now. So yes, definitely check the hoses.

Thanks everybody for the great advice! I had an awesome weekend. Wakeboarded all day Saturday and Monday(before it got busy), and went to the Indy 500 all day Sunday. I dont know if it could have gotten any better.