97 Force 120 Thermostat Dead?

[anple]

Hello Everyone,
I recently got a 17' Maxum with 97 Force 120hp. Today, I took out the thermostat just to inspect if I need to replace a new one. I saw some small sand and rocks around the housing, so I cleaned up and sprayed some wd-40 inside the housing and thermostat and put it back in. Prior to that, whenever I flushed the engine with fresh water hose, I would get water to come out after 10-15 seconds from the peehole, hole in the back of the lower unit, prop exhaust, and hole that is close to the prop. But as I put the thermostat back in, I ran the engine for 10 minutes, the only water came out was from the back of the lower unit and the prop exhaust, and a little bit from the hole that is close to the prop. I did not get the water from the peehole and steady stream from the hole that is close to the prop like before. I then took out the thermostat to let the engine ran without it, I got the water pumped out like I used to. Is the thermostat dead? Is the water impeller working properly? Can someone please advise me what is happening to the motor and how to go about fixing the problems? Many thanks in advance! - Anthony

 

[Barnacle_Bill]

Re: 97 Force 120 Thermostat Dead?

Thermostats are cheap compared to repairs due to overheating. Replace it and be sure.

 

[anple]

Re: 97 Force 120 Thermostat Dead?

I put a new thermostat and old one in a pot of water and boiled it up, both opened at the same time. I'm thinking the old thermostat was clogged with sand and small rocks the whole time before I inspected it. That was probably why I would get the water from the peehole and others. Once I cleaned it up, it has been returned to the normal working conditions. However, I couldn't get the water pumped out like before because the water from my garden hose was too cold as I live in Portland, Oregon, and it never got to the temperature (140F) it needed to open up. I'm going to take it to the river for another test. Thanks - Anthony

 

[anple]

Re: 97 Force 120 Thermostat Dead?

With the new thermostat, I took the boat out to the river today. In about a minute after started the motor and shifted forward, the water stream came out HOT and steady from the peehole. I felt the motor run more quite and more powerful. It got on plane faster than before. Now I know the motor is running properly. Before that, it ran cold, less powerful. Thanks for the great advices! - Anthony

 

[jerryjerry05]

Re: 97 Force 120 Thermostat Dead?

If you have sand and rocks in the head then you have been pumping crud. That means the rocks and sand could have settled in the lower parts of the motor.You might pull the head and replace the gasket($35) to check for clogs. A clog around 1 cylinder will cause an overheat and carbon build up causing the cylinder to go bad.This could happen.Not saying it will.
The impeller should be changed.The housing and wear plate should be smooth no grooves.Use weedeater string as a probe in the pee hole.
Water should come out quick.J