2002 225 OX66 overheat alarm at high speed

I was fishing a tournament in Missouri this past week and my boat was running fine. I hadn't run it wide open, for the most part I was running 55-60 mph, around 4300 rpm. On the last day of the tournament I drew 2nd boat out so I decided to run hard to get to my fishing area first. I was running around 73 mph for approximately 5 minutes and the overheat alarm came on. I shut down and started back up. Ran around 60 mph and the alarm did not come back on. Any ideas? I bought the boat this spring and have not had this problem before. Thought I would change the thermostats first. The water pressure was running around 15psi.

Re: 2002 225 OX66 overheat alarm at high speed

In addition to thermostats, Check the water bypass valve. Its an aluminum cap with two bolts and a hose attached to it. Its located on the back of the block , between the heads down low below the CDI computer box. There is a check valve and a spring in there. There is an updated check valve (black plastic part). The updated part is smooth on one side and no longer protrudes into the rubber grommett. When the aluminum corrodes the grommet swells and grabs the check valve making it slow to open or stick all together. Water pressure at high speed opens this valve to provide more water bypassing the thermostats.

If you don't know the service history or last time the water pump was serviced replace that as well. A marginal impeller will not keep up at high speed.

ddog

Re: 2002 225 OX66 overheat alarm at high speed

Thanks for the feedback. I'll make these checks also. I'll plan to have the water pump replaced over the winter. I won't get much more time on the water until spring.

Re: 2002 225 OX66 overheat alarm at high speed

Perhaps you were trimmed out to high and water was not getting in your motor??

Re: 2002 225 OX66 overheat alarm at high speed

I thought about that also. I don't really know though. It has a manual jack plate but I haven't adjusted it. It gets on plane quick and rides very well so I didn't want to mess with it. I'm not sure how far the motor should be in the water when it's all the way trimmed down. Another question I'll need an answer to.