Temperature warning

[Rogcapital]

I have a 2007 RZ2. Lately when I’m surfing I get a high temperature warning and the boat starts to slow. Not great combo when someone is surfing behind the boat. When I rev the engine the temperature cools down I have changed the impeller but still getting the warning and the boat slows down every time
I take the boat out. Any suggestions? Could it was a faulty sensor? Anybody else experience this?


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[Semi-Pro-ish]

Have you checked to see if the intake is partially blocked?

[SurfinSnipes]

Definitely check to see if the intake has debris and then move on to disconnecting the raw water hose from the trans cooler and checking the inlet side of the trans cooler for debris. Seaweed and other gunk loves to collect there. I have an 07 22ve with the marine power engine and my average surfing temps are around 160-165 degrees.

[Semi-Pro-ish]

There are helpful youtube videos on how to do this.

[boatwakes]

Also consider the thermostat may be sticking. Super easy to replace but BE SURE TO GET A 160* THERMOSTAT AND NOT THE 140*!!!!!!!!!

[freeheel4life]

Check to make sure thru hull valve is fully open. Make sure there no cracks/loose hoses on the intake side of impeller/raw water loop. Can suck air instead of water....

[BrentP]

Also consider the thermostat may be sticking. Super easy to replace but BE SURE TO GET A 160* THERMOSTAT AND NOT THE 140*!!!!!!!!!

So question on this. A 140 would make the engine run colder. Is this inherently bad?


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[freeheel4life]

So question on this. A 140 would make the engine run colder. Is this inherently bad?


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Yes, that's bad. Cold engines will use more fuel/run rich, will leave behind carbon build up on plugs, and dump excess fuel into the exhaust.

[SurfinSnipes]

My 2007 22VE was running "warm" and I looked deeply into why my boats operating temp was much higher than the advertised operating range. Turns out, I have the 160* thermostat installed.

IIRC Marine Power delivered these engines with a 143* thermostat and then silently recommended the update to the 160* thermostat. However, all of their literature related to the raw water cooled MEFI-5 5.7L engines suggests the use of a 143* thermostat. Oddly enough, using their owners manual as reference ( https://marinepowerusa.com/wp-conten...ERS-MANUAL.pdf ) they suggest three slightly different operating temps of 143* (PG. 8), 145* (PG. 37), 142*-160* (PG. 41).

Bakes Marine calls the 160* thermostat a direct upgrade over the 143*. The operating range of the 160* thermostat should be 160*-185*.

I couldn't imagine using a 143* thermostat in these boats, my engine runs extremely well and is more efficient than I could have hoped for. Our engine is cat-less and with a fresh air exhaust we have zero exhaust smell while surfing.

[boatwakes]

We've come across several engines recently, Mercruiser, Marine Power and a Volvo Penta with the 140* stats installed and they should not be used. The ECM stays in warm up mode until approximately 140* (doubles injector pulse width and retards timing to aid in warming the engine up faster). Although MP's literature does list a lower temperature range for it's raw water cooled engines (which is odd because no other manufacturer does this), it is imperative ALL EFI multi-port injected engines run the 160* thermostat, closed loop or raw water cooling, it doesn't matter. Only the non-computer controlled carbureted engines should run the 140* degree kit.

[KoryStewart]

I'm new to this forum, just got my first boat, it's a 2004 21i. (5.7 liter Marine Power). Been dealing with a mystery overheating issue, impeller has been replaced, had a mechanic backflush the raw water coolant system. The overheat is intermittent, will run the boat for several hours at normal operating temperature, then at idle it will overheat. I'm thinking to replace the thermostat next, any other recommendations?
I found this thread while shopping for the 143 degree thermostat recommended in the marine power original owners manual, I see I should replace it with the 160 degree stat. Anyone know where I can find this part by chance?