Raw Water Pump will not prime?

[Mitchboom88]

I replaced the impeller on my Yanmar 3YM30 (Ranger 21EC) and the pump looked good. All seemed to go well but no water discharge at the exhaust when again starting it. I Quickly shut down. Is this raw water pump supposed to be self priming? I'm reluctant to let the engine run waiting to find out. Any suggestions as to how I can fill the water intake line to the pump since I must have drained enough water to let too much air in the line
Captain Mitchell

 

[bob daily]

You did not say if the boat was in the water or on a trailer, either way the pump will prim itself. If the boat is in the water after opening the seacock it will prime in a few seconds , if out of the water with the seacock closed and a jumper hose in a bucket of water it will take a little longer. Don't get too excited just rev up the RPM' s and it will be spitting water out the exhaust before the engin gets wormed up. Good luck Bob

 

[Mitchboom88]

Thank You, Bob. I will give that a try today. The boat is in the water. I do wish there was a way to introduce some sea water to avoid damage to a dry impeller. Perhaps I was just being too cautious.

 

[PanaSeaAh]

you are correct to be concerned about a DRY impeller. If you did not lubricate it during reinstallation, try this. If you can access the discharge hose from the pump, take off either end and put a generous squirt of dishwasher detergent in he pump so it hits or runs down on the rubber vanes. reassemble and be sure all valves are open. It should prime fairly quickly if you are in the water. Certainly before any damage is done. A dry and unlubricated impellor may be damaged in less that a minute. if you cannot do this, take the cover off the pump and push Vaseline into the impeller openings, close it up and fire the engine. (I know, I know, but it is not going to sit there)