2009 moomba outback v running hot

[Thrift]

My boat is runs hotter the faster you go! If you break down to an idle it will cool back off but putting it under strain run the temp up! It has a brand new impeller but it didn’t fix the prob! Thinking it has a clog somewhere but not sure where to look?? Any help would be appreciated

[zabooda]

The impeller operates at low speeds and idle. When you are up on plane, cooling is essentially hydrostatic flow so I would suspect a restriction somewhere. Probably at the intake or filter if you have one.

[Stazi]

Could be the actual engine water pump is bad, no, not the impeller, the water pump on the block. Also check any strainers for blockage with weeds etc. and also check inside the heat exchanger (for the engine oil) that is on raw water the feed hose from the raw water pump to the thermostat. That can clog with weeds and shit and well.


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[Stazi]

The impeller operates at low speeds and idle. When you are up on plane, cooling is essentially hydrostatic flow so I would suspect a restriction somewhere. Probably at the intake or filter if you have one.

This is incorrect. Raw water pumps works all the time. Hence why it’s directly connected to the crank. If it fails the engine will overheat, and also the exhaust manifolds will overheat first. As a lot of the raw water is expelled out of the exhaust to cool the jackets in the exhaust manifold.


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[VA LSV]

Check the transmission fluid cooler just after the raw water pump for weeds or debris. Could also be the thermostat not opening all the way.

[Stazi]

Check the transmission fluid cooler just after the raw water pump for weeds or debris. Could also be the thermostat not opening all the way.

Yep. Same thing I said.


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[mmandley]

Most Likely the thermostats, Trans Cooler, Heater, even exhaust manifolds are all subsystems.

Thermostat is the primary restriction point on the engine, also water being re-directed to the exhaust manifolds will not cause the engine to run hot. The engine running hot will cause the manifolds to run hot.

Don’t quote me as I have to look but from what I recall the Exhaust is cooled by a separate hoses from the water pump so technically it’s completely separated from the engine cooling.

[DOCDRS]

Over time the thermostat can accumulate oxidation build up and when open will no allow enough water to escape the engine. Check if your manifolds and exhaust rubber pipes are hot. How hot is your temp gauge reading? How long have you had the boat?

[Thrift]

I’ve had the boat for 2 years! I’m not sure how hot it will run but the longer you run the hotter it gets! I haven’t got it over 200 without backing off! When you drop back to an idle the temp drops pretty quickly

[Stazi]

Sounds like the thermostat might be stuck closed.

Have you check the oil cooler right after the impeller pump to see if it’s clogged?

What have you checked/done?!?!!?!!!?


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[DOCDRS]

Has this just started after winter lay up and summerization?

1 check all clamps and strainer gasket seal to ensure you are not sucking air.
2 check the tranny cooler
3 remove the thermostat and distribution housing and look for corrosion. Remove tstat and test it in water on the stove.

if all are good then the seal on the impeller pump could be going.