Mercruiser Temperature Issue

[daceman63]

Originally Posted by beamie

I assume this is fresh water cooled and not just raw water.

No. It is only raw water.


How does it run under load? Last year I had an issue where the temp ran up to 180 and fluctuated back down to 140 before beginning the process all over again. There was at the time also a vibration from the motor. It turned out to be the raw water pump. That was replaced in the off season

Does the raw water first pass thru a oil cooler before going to your heat exchanger? May be plugged up. Without the thermostat in the water flow and exhaust is strong and steady. Is the oil cooler a big deal????



Belt isn't slipping? No, the belts are nice and tight...

Did the engine get very overheated at some point and you have head gaskets issues? Eroded impeller on your fresh water side? No fresh water side....as i said got to 180 last year. No water in the oil....it's nice and clean and at the correct level.

There was no blockage of your manifolds in 2001? That was a loooong time ago. Your manifolds are on the raw water side? That is a mistake right there. They should be fresh water cooled with a solid gasket going to the riser.

The manifolds were replaced in 2001. When we took them off they were clean and we hooked a hose to them and water flowed through freely. Could they be the issue?



150-155' seems a bit low operating to me? It's always operated like that since I got it...

I'm not an I/O guy but I assume the Bravo drive sucks raw water up thru the skeg. Yes

Is there a plastic piece going from drive, to hose, to into the boat? that may be cracked or loose s#^&#^&#^&#^&#^&g in air with the raw water causing fluctuations. I don't know. I'll have to pull the boat to see that...


Thank you for your help....

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