06 340 assault water temp issues

[Broke Pilot]

I posted this on the supra forum, but we all know how hopping it is over there! Lol
while we were out yesterday my water temp gauge starting acting weird. We were headed back to party cove on Conroe and was on plane running around 3700RPM... I started feeling what felt like cavitation (kind of pulling the boat back) off and on as we went over a shallower spot in the lake, I figured the currents were swinging and pulling on the boat. When I looked at the helm I noticed my water temp gauge was around 130*ish. It never got back above that mark the rest of the day, but the boat ran just fine.
What do these 340 engines normally run temp wise? I see online people sayin 140-160*, but aren't the thermostats 160*? Mine usually sits around 180 idling and a little cooler when moving.
So in Yall's opinion, should I be looking more at the temp sender or the thermostat? I'm going to replace both, but I wanna do it one at a time and figure out of the t-stat stuck open or the temp sender is dying... Thanks!

[icemanftr]

Always fix Thermostat first. That is the one that can fu** your motor. A sensor issue isn't gonna cause your engine to overheat, as it's just a simple sending unit.

Yeah those supra guys aren't chatty at all.


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[Poison]

My 2007 340 CAT/ETX sticks right at 180. It's held steady at that temp since the day I bought it. I remember reading a long time ago that the CAT/ETX engines run hotter than the regular ones, and that it is normal. I was always concerned after reading that most boats stick to 160 deg, but mine has always stayed at 180 on the dot after warming up.

[MJHSupra]

My 2007 340 CAT/ETX sticks right at 180. It's held steady at that temp since the day I bought it. I remember reading a long time ago that the CAT/ETX engines run hotter than the regular ones, and that it is normal. I was always concerned after reading that most boats stick to 160 deg, but mine has always stayed at 180 on the dot after warming up.

160-180 would be normal. Getting to 200 would probably start trouble on water cooled motors.

Therm would be cheap and easy to change now


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[Broke Pilot]

Well, I'm gonna stop by Rinkers and grab my new tower foot pads and a thermostat if I can ever get home from this trip...

[dusty2221]

Better get it straightened out, the jam is coming quick!

[Broke Pilot]

I know... And I have so much work to do! New amp for the rev410, tower foot pads, cleaning, and the list goes on. Anyone wanna come work on the big girl for me?!? Lmao I'll provide the beer!

[dusty2221]

I know the 24 like the back of my hand, if you were further north I'd be on my way!

[Broke Pilot]

Trust me, I'm looking forward to meeting you. I have some questions about your stereo install you did on yours.

[Broke Pilot]

Update...
Well I solved the issue where I thought the boat was hesitating or losing power at speed. My fuel pump was dying. Went out Saturday and as soon as we got outside the no wake zome and gave it gas it choked out and tried to die. New pump and filter and she's back up and running stronger than ever!
While I was out though I was getting temp fluctuations. It didn't indicate over 140*, but every now and then it would rise to 170ish at idle and then drop back down. Now it's time for a new t-stat...

[dusty2221]

Glad you found the issue!