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Last March I replaced the impeller on a 1958 Evinrude 18 HP with a Sierra 18-3002 impeller ($23.50 USD). Ran the motor for one month from June 13 to July 12. Before I took the pump apart I noticed that effort to turn the driveshaft was high. The pump was clearly dragging. Took the pump apart yesterday and the vanes are set (curved permanently). Here is a photo.
Heard that replacing the impeller every 2 years is recommended. The vanes are still pliable although set.
Should I replace this impeller after one month of service? Would appreciate any comments from people with more experience.
The impeller probably is OK. I’d consider that pump housing to be worn out though. Your choice.
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“Before I took the pump apart I noticed that effort to turn the driveshaft was high. The pump was clearly dragging.”
Possibly you got one of those fat impellers Sierra has.
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I had a 1954 Johnson CD-11 5.5 hp that had an almost new Sierra impeller, so when servicing the motor, I decided not to replace it. Sold the motor to an acquaintance.
The guy called me up and complained that it took him two hands to pull the motor over, so I offered to fix the problem. Just as others have stated, the Sierra pump was the problem. It was too tall and rubbing hard on the impeller plate as well as the housing.
When comparing the Sierra impeller to an OMC impeller, there was clearly more of a step-up from the brass hub to the rubber on the Sierra. I sanded the impeller on a lapping stone with 220 gr. until the rubber was nearly even with the brass hub on both top and bottom. Problem solved.
Most Sierra parts are just fine, but the impellers and points not so much.
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I had a 1954 Johnson CD-11 5.5 hp that had an almost new Sierra impeller, so when servicing the motor, I decided not to replace it. Sold the motor to an acquaintance.
The guy called me up and complained that it took him two hands to pull the motor over, so I offered to fix the problem. Just as others have stated, the Sierra pump was the problem. It was too tall and rubbing hard on the impeller plate as well as the housing.
When comparing the Sierra impeller to an OMC impeller, there was clearly more of a step-up from the brass hub to the rubber on the Sierra. I sanded the impeller on a lapping stone with 220 gr. until the rubber was nearly even with the brass hub on both top and bottom. Problem solved.
Most Sierra parts are just fine, but the impellers and points not so much.
I had one of those CD Johnsons and it became to hard to pull. It turned out to be the shock absorber was broken. It was to long and it was pressing on the water pump housing.
My experience with impellers on OMC motors goes like this. I put the impeller in the housing. Move it to the side where it would be if installed on the leg. If the paddles don’t touch the housing I change it.
dale
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big improvement to say the least .. should work but I am not a pump expert I just wirebrush them.. never had a problem. apply a touch of grease when reassembling.
Joining AOMCI has priviledges 🙂
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Charlie,
The pump looks much better after machining.
David Bartlett
Pine Tree Boating Club Chapter"I don't fully understand everything I know!"
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