Cooling system woes continue

Carl

Well-known member
Staff member
Changed out the impelller on my Merc 25hp this morning. Two results:
Does not shift into gear, I think I have the shift linkage and lower unit out of sync. Easy fix , just gotta drop the lower unit again.

However, with new impeller, it?s still not peeing. I will blow out the cooling system with air and water when I re-drop the lower unit. Will try to pull off the thermostat too.

Any other advice from the brain trust on both issues??
 
Carl, I've got a limited experience with OB cooling systems but have replaced a couple of impellers over the years - my thoughts:
1) Linkage issue is separate from cooling system.
2) Are the impeller vanes installed correctly? Once you have the lower unit off, turn the prop while watching the impeller to confirm.
3) Are you running the motor in a barrel, bra & hose or off the boat? If with a bra make sure your hose is fully ON. Then rev to a bit higher RPMs to get the water moving.
4) Certainly blow air through the system.
5) With the cowling off can you see water anywhere?

Had an issue with my Honda 9.9hp this spring not peeing. Just replaced the impeller a year ago. Did all the above - the result? Hose wasn't supplying enough water to the intake (after taking everything apart........twice :)
 
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Linkage was an easy fix. I didn?t line up the connection correctly

Cooling was too: tube from thermostat to pee hole was clogged with shell fragments and sand.
Ran it in a tub of water for 5 minutes, good strong stream of water now. And I adjusted the idle too.
Back in business.
 
Carl said:
Linkage was an easy fix. I didn?t line up the connection correctly

Cooling was too: tube from thermostat to pee hole was clogged with shell fragments and sand.
Ran it in a tub of water for 5 minutes, good strong stream of water now. And I adjusted the idle too.
Back in business.

Hey Carl -

Great feeling when you fix an issue isn't it.

In regards to the pee hole. I used to have similar issues where the hose to the pee hole would get clogged and cause problems. On my Evinrude, the hose from inside ran to a fitting that then connected to the hole in the cowling. This connector reduced the diameter of the hose and thus caused a restriction of sorts. I was told to just remove the fitting and pull the hose directly through the hole in the cowling and I would have no further issues. I did as suggested and they were right - no issues.

Just passing along.

Mark
 
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