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Universal Engine Cooling (Fresh Water)

GMaurer

Member II
A lot is made in the Manual regarding the raw water pump impeller replacement (including detailed instructions), but nothing is stated regarding the fresh warter pump, which is belt driven.
It would seem that this pump is just as vital as the salt water coolant pump - is it bullet-proof, and therefore maintenance free?
If this is not the case, are there recommended spare parts?
 

Ray Rhode

Member III
I think the freshwater pump is the same as the water pump on your car. It is a centrifical type pump and the most prevalent failure mode is a leaking shaft seal. The raw water pump impeller must remain flexible in order to pump correctly and the vanes become brittle and break off or wear and lose their seal and therefore lose their pumping ability.

An idea I saw in a book full of ideas was to install a strainer in the raw water line between the pump and the heat exchanger. Then when you loose a vane it will not clog the heat exchanger.

Ray
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Closed Cooling System Pump...

When I re-hosed my engine (M25XP) I asked a tech at Universal-Westerbeke about the pump, and he said that as long as the shaft seal is not leaking the pump should last until around 4500 hours. It is an iron impeller pump, as others have pointed out.
I have about 1500 hours on the engine now, and have no leaks...

Loren
Olson 34 #8
 

jreddington

Member III
If you have a Universal M-15 and it has been converted from raw water cooling to closed loop cooling, you probably have an impeller on the coolant loop. Mine came with identical Sherwood raw and coolant pumps. Raw has been swapped out for an Oberdorfer. However, retained the Sherwood for the coolant loop. The coolant pump is on the back side of the enginer. The Oberdorfer is too big and will not fit in the small space between the block and the bell housing. In fact, the Sherwood is so tight you cannot pull the cover and replace the impeller in place. You have to unbolt the entire pump, slide it out, replace the impeller and then reinstall the pump.

While I inspect the raw water pump impeller at least once a season, because of the tough access, I'll go three seasons with the coolant pump. And then I just replace it even if it looks good. A new impeller is cheap compared to the trouble of inspecting or replacing. Not sure what the normal life of the coolant impeller would be. On one hand, it is not exposed to salt, grit, etc like the raw water impeller. On the other hand, it is circulating hot fluid which could accellerate rubber aging. So far, when I pull the impeller every three years, it is pristine. Not going to push it to four.
 
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