1999 Sylvan deck boat water temp issue

[TriLakes boater]

I have a 1999 deck boat with a GM 4.3 liter motor and Volvo Penta outdrive. Lately, my water temp has been higher than normal. Last year it would peg around 175, but this year it is a little higher and has come close to 250 before going back down. My immediate thought is replace the thermostat as it sounds like it is sticking. It seems to be worse if the boat is idling in the water. There is no grease indicating a water pump failing.

 

[alldodge]

When was the last time the raw water pump impeller was changed?

 

[TriLakes boater]

I just bought the boat last September and I have no service records. I think the impeller is on the front of the engine under the harmonic balancer. If so, it seems like a straight forward job.

 

[alldodge]

I just bought the boat last September and I have no service records. I think the impeller is on the front of the engine under the harmonic balancer. If so, it seems like a straight forward job.

Yes, that is one of the first things to replace when you get a boat. Then replace every 2 to 3 years afterwards, I replace every 2 years

 

[TriLakes boater]

Any special tools need to replace the impeller?

 

[alldodge]

No, just regular stuff.
Do not use oil or grease on impeller to reinstall, use liquid soap or glycerin (KY jelly)

The impeller rotates clockwise facing the motor, so make sure the impeller blades bend that way (rotate the blades clockwise when installing)