Water temp runs 15 degrees high
 

Boat was in storage for almost two years. First run I noticed water temp at about 175 when it was at 160. Pulled the t-stat, which looked a little crudy, and put a new one in. Also found that it had the wrong t-stat as the manual calls for a 140 degree. Also replaced the water pump impeller which was fairly chewed up. The temp guage now runs at 155. 15 degrees too high again. While running the boat on the hose, I saw a couple drops of water come flinging up at the front of the motor. I thought prob the water pump going but it stopped immediatly and I could not find any water around the pump. I ran the boat for nice cruise Friday night and noticed today a small amount of water in the bilge. It was dry when I went out. The only things I can think of are the water pump, but why would that give me a consistent 15 degree high reading at idle or wide open. The other being a pretty good chunk of the impeller was missing. It wasnt in the t-stat housing and I woould think the water pump would destroy it. It was a piece about half the size of one of the blades. ANy thought on this would be appreciated. Tomorrow I will let the boat run on the pump awhile and check for leaks. I leave w/boat on 12 day vacation on friday and need everything woking properly.

Check for the piece of the impeller in the inlet of the oil /powersteering cooler. just follow you cooling lines and you'll locate the cooler.Also the engine will run a higher temperature than the thermostat temp. Hope this helps

My 454mag has a 140 t-stat and has always showed 150-155 on the Faria guage. I wouldn't worry about it. If the temp stays consistent at 155, its fine. Mine would also creep up to 165 at the initial start up and after a hard run.

Have you checked the guage to be sure it isn't 15 degrees off? Is this a closed cooled engine?

OPen cooling system on a 10 year old OMC King Cobra 454. I thought about the guage being off but I guess I would need another guage to check it?

A thermostat doesn't start to open until the temp on the stat. Then its fully open at about 15 degress more.

Its normal for an engine to run 10-15 degrees higher then the thermostat rating. If you have a 140 degree stat all it means is that the stat will open at 140 degrees. The actual water temp will vary depending on conditions and where you measure the temp at.

Ron