www.iFourWinns.com

Hello I have a 97 horizon 200 GXi EFI. When I am at idle in the water the engine temp gauge sits right in the middle 150 degrees. When I get up to plane the engine temp gauge goes way down, like it is not even registering, it is a slow drop takes a minute or so. I dont think that it has to do with a bad gauge, I think that the engine is really running that cold at plane. Is this something to worry about? I have been told that the engine should stay at appx. 150 degrees or in the middle of the gauge even at plane. Any ideas on what I should check?

Thank you
Tom

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Tom MacLean
Fremont, california

The first thing I would do is replace the thermostat. They are cheap enough. Also, at the same time, I would replace the raw water impeller if it hasn't been replaced in the last 200 hrs or two years of use.

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Jvalich
http://www.badcock.com

'04 FW 288 Vista "Mental Floss"

Check the temp of the engine. Maybe where the cooling jacket is or at the pipe. If the engine is warm after the gauge reads cold, look at the guage and/ or sending unit. If the engine really does cool down, then I'd guess a bad thermostat?

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2007 Horizon 200
4.3L GXi/ SX 225 HP

its a bit normal so see a little dip but one that large is not right plus you should be reading around 175-180 so I would say the thermostat is stuck open. I wouldnt worry about the impeller because it looks like it is moving water just fine.

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Four winns 180 horizon

I have a 2002 5.0GXI and it sounds like yours is doing the same thing that mine is. I replaced the raw water impeller and the thermostat and it's still doing the same thing. Normally I wouldn't really care that it's running too cool except that the engine cuts in and out when you go past 3/4 throttle because it thinks it's too cool to operate at the high of speed until it will warm up which it never does of course unless you sit and let it idle for awhile. Let me know if you find the cause of the problem and I'll do the same. Mine is in the shop right now and they are scratching their heads with it.

Thank you very much for the suggestion of changing the thermostat. Once I replaced that the temp gauge stayed pretty much right aroun 150.

Thanks

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Tom MacLean
Fremont, california

I had the same issue with the temp gauge, changing the thermostat solved it. I found that with raw water cooling, they get sticky after a while and don't close all the way, and tend to open and close slower than a new one will. Tested new and old side by side in a pot of boiling water with a car radiator testing thermometer.

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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

My boat would warm up at idle and bottom out when I shoved it down to go. The thermastat was the first to get replaced. Didn't fix it. I also replaced the raw water pump and engine circ pump. I didn't think either one of those would fix it. They needed it anyway. Here is what I found: Chunks of raw water pump in the thermastat housing. It must have been redirecting water some how through the engine instead of the exhaust. It must have been from an old raw water impeller. The one I replaced was perfect. I just wanted to help. Thanks James C. Gorman 1997 18' Horizon RS Volvo 4.3GI SX drive

150 degrees at idle is fine. If your not overheating when the engine is under load then this should be of no concern. When your idling the cooling system is not circulating as much water through the engine causing the temp to rise. You could bump up the idle slightly and this would correct the issue.

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1986 Horizon 190 - Fully Restored