www.iFourWinns.com

Problem. Since it came out of winterization, it has been having a strange temperature problem. With the boat at idle in the driveway (muffs on), it will climb to around 150, and stay there. At the lake, after running at speed for about 30 minutes the temp will still be around 150. After this point, the temp will slowly rise up to around 200. Then it will go back down to 150 randomly. Then climb back up to 200. The highest it has gone is about 210. The gauge goes to 240. It seems like it goes down when giving it more throttle, but it very difficult to tell. It will continue to move the entire time. The thermostat was replaced a year ago, and impeller replaced two weeks ago. The needle is not jumping, it is slowly rising and falling.

Thoughts are thermo, water pump, debris somewhere, exhaust, blown head gasket

Suggestions?

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1990 Horizon 200
5.7L OMC Cobra 260HP

Overall, I say start simple and work from there. Do you have one of those fancy temp guns? Verified gage accurate, etc.

Let's start with Debris first by disconnecting some cooling hoses and blowing out with air, then water.

Next the T-stat... I would pull and check the T-stat (put in water on stove, yadayada)... seems almost like it's got an "automotive" setpoint, as it apears to be "regulating".

I hate doing the water pump on the B1, hence it would be last to check.... especially since done recently; but what about the engine mounted water pump?

Just thoughts... no real answers. Best of luck.

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Walt B
"Debt-Charged"
Black '07 H210SS
6.2L Bravo One turning a 21P HIFive
Wakeboard Tower with Perfect Pass Stargazer version
Missouri River; Kansas City, Mo.

Alright everyone, turns out the problem with the overheating was a tube inside the outdrive that was put on crooked during the install of the new lower unit. Found this out after replacing impeller, circulating pump, thermostat, and thoroughly inspecting manifolds and exhaust risers. found out water was not entering thermo housing at idle, which meant something in the outdrive was messed up. FINALLY everything is complete and running great. Ready for (hopefully) a smooth summer.

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1990 Horizon 200
5.7L OMC Cobra 260HP

Thanks for the feedback, it helps to know what the solutions to problems are. On mind, because it gets moored in salt water, I have had barnacles growing in the drive water intakes. I usually break them up with a really small screwdriver and blow out the bits of the shells with compressed air and then back flush with water. Have never had an over heat, even with some small barnacles in there.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II