2005 150XL Saltwater: Runs Hot in rough water -only?!

[Gator167]

Issue: I hope someone can give me a direction, because I am stumped. I bought this boat and engine a week ago. Before buying, myself and the mechanic took it out on a big lake in Tallahassee for a test drive and everything ran great, cruised at top speed, let it idle, everything. So the next day I take it out to launch. Engine starts perfectly and we idle in a no-wake zone out towards the bay, where there is a moderate chop. We get there, I throttle it up and in about 15 seconds the constant beeeep alarms, that indicates overheating (gauge=175). I throttle back down to neutral and in a few seconds it stops. I try about 4 more times in the bay, same thing. Finally we idle back into the bayou to load up and I decide to go ahead and try it one more time. This time, its just like it was on test drive on the lake. No alarms, running 45 MPH, everthings perfect. We then changed the thermostats, took it out a few days later, same exact thing, I can run all day in smooth water, but hit some chop and the temp goes up and the alarm goes off.

Why in the rougher waters I am having a high temp alarm, and in smooth water everything is perfect? I have changed the thermostats and the impellor looks fine. I have also talked to two separate Marine Mechanics and both seemed perplexed why it would overheat in rough waters as opposed to smooth. Also, the boat is a 2005 Trophy 1903 CC and the engine is mounted in the exact same place it was mounted when new from the dealership, in the 3rd holes from the top. One mechanic looked at it and said it should have plenty of pick-up. Help please!

 

[CharlieB]

Re: 2005 150XL Saltwater: Runs Hot in rough water -only?!

Check the water pump lower half for warping. Works well SUBMERGED but once in the chop is un-covered with water and starts sucking air.

 

[Gator167]

Re: 2005 150XL Saltwater: Runs Hot in rough water -only?!

Ive got a new water pump on the way, should be here Tuesday. I have the foot off of the motor right now.What would a warped waterpump look like?Thanks for the adviced.

 

[Gator167]

Re: 2005 150XL Saltwater: Runs Hot in rough water -only?!

Bump.

I dropped the foot and took off the waterpump housing. Everthing looks pretty clean in there ( the motor looks about brand new, really) . However, when I pulled the gaskets off, the bottom gasket, the one that rests against the blue bottom piece, had a torn place sort of in the middle of the gasket. Could that be the culprit? Any help is appreciated.