The OMC power steering & oil cooler are bigger than the single merc combo cooler off the 330hp motors so I'm still using the OMC coolers so the oil flow hasn't changed. I also replaced the impellor & housing just to rule it out... no change. I have the intake hose from the transom going to the top port on the sea pump & the lower port connected to the coolers/engine. This is a v belt drive sea pump so I believe this is the correct flow? Wouldn't it not cool the motor @ all if it was hooked up backwards?

Do I need to remove the drive to check for the "Bravo Fever" mentioned? Can someone walk me through how to check this.

If it hit 240 as many times as you said it did it would not be still running . I would put a 140 stat in it and start looking for a ground problem . just my .02 worth

Try flshing water from the inlet hose of the raw water pump out the drive. If you can't get good flow, then yes, you'll need to statr working on the drive portion. It can corrode & collapse at the transom or the belhousing connection.

The other possibility is that the hose between the transom & bellhousing is collapsing under suction. I've heard about that one.

But, before I started disassembling anything, I'd fix the electrical issue to make sure I knew what the temp was at all times.

What i was trying to say was check the incoming water volume coming into the cooler (apollard basically said it too) so I would dump it in a 5 gallon bucket and see how long it takes to fill up and garden hose or otherwise cool the system while you're testing. Those pumps should easily hit 20 gals per min. They're designed for 27 if my memory serves.

Russ

Still chasing this problem. Spliced into the wire harness & installed another jumper from the ground wire directly to the battery….no difference. The temp sender does have a sealent on the threads. Should I clean that stuff off & try it without any. Maybe that’s not allowing it to ground properly.

I ran water from the intake back out the transom / drive & the flow seems normal. I haven’t tried filling the 5 gallon bucket yet. I did have a inline hose adapter in that intake hose & wonder if its leaking & allowing loss of suction. I ordered a merc intake hose & will leave that adapter out & try it again.

The seapump is used primarily for cooling when the boat is idling or moving slow. At planing speeds water is forced throught the system by the movement of the boat. It sounds like a bad seapump to me.

That fricken hose adapter was causing the higher temps @ idle. Removed the swival for the hose & installed a plug, problem solved.