Overheating Issues!!!!!

[Kmestep]

I've got a 94' Mariah Talari w/ 300 hours. It runs the Bravo III, Mercruiser 350. It's a great boat but the dang thing won't stay cool. I've replaced the SeaWater Pump, put a cooler Thermostat in, brand new Impeller and still have problems. One weekend it will run fine (stays cool). The next weekend it will run hot. Only after removing the SeaWater Pump and tinkering for a minute will it begin running cool. Anyone have any ideas?

 

[dallas T]

Re: Overheating Issues!!!!!

How did that impeller look before you repalced it?<br /><br />Maybe you have a sight blockage and/or some sand/junk/impeller parts etc. floating around the system causing flow issues.<br /><br />Maybe try backflushing. Not familiar with your set-up but if this is like my raw water cooled system, there are components on the exhause end (elbos etc) that corrode and get blocked too.

 

[Kmestep]

Re: Overheating Issues!!!!!

The previous impeller was, well, not in good shape. I removed all hoses associated with the cooling system and flushed them so I don't think (emphasize "think") there is any blockage.

 

[Kmestep]

Re: Overheating Issues!!!!!

The previous impeller was, well, not in good shape. I removed all hoses associated with the cooling system and flushed them so I don't think (emphasize "think") there is any blockage.

 

[tommays]

Re: Overheating Issues!!!!!

it sounds more like you have and air leak and its haveing trouble primeing<br /><br />how is the pump case and seals<br /><br /><br />tommays

 

[Kmestep]

Re: Overheating Issues!!!!!

Not very familiar with the Pump Case and related seals. I'll check them out in the manual though. As far as the Elbows, I never thought to check them. Any other ideas as to what it would be?

 

[rbezdon]

Re: Overheating Issues!!!!!

Risers (elbows) and manifolds commonly become severly rusted inside and clog or leak water into the exhaust chambers. hese need to be replaced every few years for a raw water cooled, fresh water boat and more frequently for a salt water boat.<br /><br />The pump case is the housing around the impeller you replaced. You needed to inspect it for damage from te old impeller.

 

[Kmestep]

Re: Overheating Issues!!!!!

All good information. I'll see where I get this weekend with repairs!

 

[michaelfagan]

Re: Overheating Issues!!!!!

If you have a heat exchanger, open it up and check it out for blockage.