2002 SAN GT-40 overheating...thinking it's the thermostat? Looking for advice

[youngunz]

PCM Gt-40 over heating. Suspect it is the thermostat. When I dunked the boat I knew very quickly water was not folowing past the thermostat. Pulled the boat back home and took everything apart. Appeared to be seized.

Would assume that some part of it should open/actuate at a given temperature. Is that correct?

looking at replacement parts I wasn't too sure I should purchase the 143 or 160deg thermostat?

Is this standard, could it be purchased through Ford?

Thanks.

[nukemustang]

If you want a quick check, boil a pot of water and throw it in. If it doesn't open, you know you got a bad one.

143F is for carbed boats, 160F for EFI. http://www.nautiqueparts.com/search....ind=thermostat

[youngunz]

Yeah I tried the boiling pot of water, nothing. Crossing my fingers that the thermostat is the culprit. Would it also be in my best interest to replace the temper sender?

[DLafont]

Put my boat in this past Saturday, started up and I drove around the bay in front of boat launch, noticed the temp reading was quite high (plus with water relatively cold, this rang an alarm bell). Opened the cover and saw the intake hose to the strainer was loose and not much water was making it into the strainer. Tightened all up and everything ran fine afterwards. No clue if this might be what's happening with yours, but thought I'd share. Sometimes, simple solutions can be right in front of us. Good luck!

[nukemustang]

Yeah I tried the boiling pot of water, nothing. Crossing my fingers that the thermostat is the culprit. Would it also be in my best interest to replace the temper sender?

If you watched the temperature change, the sender should be okay. Usually if a sender fails, it will fail open or short out and read constantly high or low depending on the failure state. If you could watch the temp rise and rise, then I agree, you could be looking at possibly more blockage, but if the thermostat didn't operate, I would go there first.

[youngunz]

Luckily when we put the boat in the slip I used was free and I was able to stay in place. I knew something was strange when the rubber right before the exhaust manifold was getting really soft. After about 1min all I could see from the stern of the boat was white/milky exhaust. First thought it was burn off from winterizing, however when it continued I took precaution and turned off the boat. No leaks from what I observed around the water strainer. Water is very clean where I put the boat in.

Temperature gauge didnt move, although I didn't run the boat for long. When I shut the boat off I didn't see the gauge move at all, remained around the 100deg marker. When we disassembled the thermostat there was no water on either side. I expected that it wouldn't be on the downward side because it in fact didn't open, but what surprised me was that I didn't see water on the incoming side. Could there have been a air pressure block?

Waiting for parts, hoping all it is was the thermostat.

[Tom_H]

Do you have a valve on your intake, and is it open? If you have no water up to the thermostat, I'd be looking at the impeller/raw water pump before looking at the thermostat. Either way - it sounds like you weren't drawing water. In either situation, your impeller is likely hosed and will need to be replaced if the raw water pump was running dry. (might also look to make sure the pump isn't installed backwards (which wouldn't draw any water).

[youngunz]

Valve on the intake was open, and water was flowing in and thru the raw water impeller. Used some food colouring before starting the boat as a way of tracking. When we started pulling the hoses. If I understand the thermostat correctly, water flows up to the thermostat and has the ability to flow directly down one route, and secondly down another once the thermostat reaches a limit opening releasing water to the exhaust.

Everything seems to flow when we had the boat in the driveway using the garden hose to fill the lines.

[Tom_H]

The garden hose can overcome a bad impeller as you're pressuring the water in. If you want to check the impeller at home, best bet is pull your intake hose and stick it in a bucket of water and see if it draws the bucket down. If it does, your raw water pump should be in good shape.

[youngunz]

Just installing a new thermostat in my 2002 with a GT 40 ford engine and it shows to install the arrow on the thermostat towards the rad. But since I do not have a rad I assume that means to install it towards the transom/ exhaust.Looking to see if that is the right assumption.

[youngunz]

Was able to test the boat today after installing the new thermostat and temp sensor. Everything checks out, water cooled everything as expected. Temp gauge increased as the boat ran as expected. Although it was a delay, learned a lot and glad the boat can head up to the cottage.

Thanks for everyone's help!!!