Recommendations after SD 260 "overheat". Not cool.

BC-Sea

New Member
Aug 4, 2022
2
Boat Info
260 Sundancer 2004 trailered behind "Big Red" an 05 LLY Chev Duramax
Engines
350 Mercruiser Mag w/ SS props on Bravo III
Hey Experts,
New guy here! Hopefully I'm following forum etiquette. Though I consider myself a capable DIYer, I'm still learning boats as I probably always will so appreciate a little help. We own a 2004 Sundancer with the 350Mag-Bravo 3 combo. While trying to get her out on the water for our first outing of '22 on a hot Summer day, alarms started going off but we were fortunate to be close to our fresh water launch being we didn't get far. Crap, day ruined. Drifting and waiting for cooling temps isn't fun. She is raw/open water cooled, (I wish not) has between 5-600 hours but is 18 years old. I pulled the raw-seawater pump and found the impeller fried, torn to bits and jammed into the port. The backplate is pretty grooved up but shaft bearing spins ok without play. My question. Should I just buy a water pump repair kit? New pumps especially Mercs quicksilver pretty spendy but then what isn't on a boat right. Also found a completely torn exhaust bellows so bought a rebuild kit and will replace all the bellows and seals etc.
I know too long. I'm just wanting help with what else should be replaced. Thermostat? Should I snake the hoses for impeller chunks too? Other suggestions for parts replacement?
Thanks in advance, I appreciate your knowledge.
 
In any overheat situation, the stat should be replaced, as they tend to get wonky afterwards.

On the raw water pump situation, which style do you have? If it's the plastic one, then by all means, replace the pump housing / body, since BBQing the impeller has probably compromised the plastic body, too. I am a big fan of the Harding Marine S/S pumps. Have converted to them on all the 7.4 and 454 Mag Bravo 1 or 3's I have owned and never had a problem with them, and they are basically bullet proof, but a tad pricey. https://www.hardin-marine.com/

The chunks of the impeller will flow down stream to 1st likely stop, the oil or PS fluid cooler. Any considerable pieces will be in the 1st cooler and will need to be cleaned out. Pull hose off inlet and get a shop vac hose in there to pull everything out.
Anything that gets past that is probably small enough to get stuck in stat housing or puked out the exhaust.

Also on an overheat, check ALL the hoses connecting the exhaust system inside the boat AND your exhaust flappers inside your "Y" pipe, as the tend to fall apart if they get too hot.

Good luck
 
Last edited:
Thanks for the information Bill, much appreciated. I forgot to mention my WP housing is all brass. I went to Hardin Marine's website, their pumps do appear bulletproof.
I kept shutting her down before temps climbed near boiling so hoping things aren't too bad.
I'll continue to do research while hoping my damage report stays minimal.
Thanks again for your support.
 

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