Another power loss quest.

[RBaum]

I have a 2006 Mercury 40hp (sn:1b235883), 3cyl, 4 stroke, mounted on a 2006 bass tracker, that has loss power at 1/2 to WOT. Here is some history about my engine. Last season I hit a sand bar here in beautiful GA that packed sand all the way up to the pee hole. We immediately cleaned all of the sand out, so I don't think it ran hot. To this day I am getting a strong stream coming out of the pee hole. When I run the engine in my driveway with the hose hooked up I can run it with out the dumby siren coming on. When I put the boat in the water I can run it all day at 1/4 throttle. As soon as I put it in 1/2 to WOT the dumby siren comes on immediately and the engine sputters (doesn't die completely) and there is no power. I am in the military and during deployments I have put stabihl in the tank. Now that I am retiring in two months, I am trying to get her right as I will be spending A LOT of time on the boat. What could be the problem?

Thanks in advance for all of your help.

 

[RBaum]

Re: Another power loss quest.

After talking with a friend of mine who's boat had the exact same problem, in a year newer model than mine. A mechanic replaced his water pump and his problem was solved. Well today I changed the whole pump assy. The stream from the pee hole was A LOT stronger. We took her down to the river and took her out for a test drive. The boat ran strong for 10-15 mins, like nothing had ever happened. I brought it to an idle and then gave it gas again, now I am having the same symptoms as before.

What could be the problem?

Thanks in advance!!!!

 

[RBaum]

Re: Another power loss quest.

I fixed the problem. The thermostat was corroded shut and the water jacket still had sand in it (from hitting the sand bar). I cleaned/flushed it out and replaced the thermostat.

Everything is good to go.

Thanks for EVERYONE's help!!!!!