prime raw water impellers?

[g36]

i have f-32 just purchased and am having my boat pulled for bottom job. i read somewhere that the raw water system needs to be primed when putting the boat back in the water so as not to burn up the impellers, because they are not self priming is this true? and how is the easiest way to do this? i have the lm318 225hp chryslers with sherwood raw water pump g5. any suggestions thank you.

[JuiceClark]

I just replaced them on the 454s in my F-36 and did not prime them. But it's not a bad idea - now that you mention it I wish I had. I'd say just disconnect a hose above the pump and pour water in there.

Tony in Ft Myers, FL

[Coralkong]

I don't know if you can fully "prime" them, but it wouldn't hurt to try, I guess.

Also, a good thing to do is lube the new impeller with liquid dish-soap. A bit messy upon reinstallation if you get it all over your hands, though.

It helps to keep it slippery on the first startup, until the impeller primes up, and also you can instantly tell if you're pumping good water out the exhaust from the bubbles.

I did mine and didn't prime them with water, but I DID do the dishsoap trick. It worked wonderfully!

[jddens]

While on this subject.....is there a rule of thumb as to how ofen raw water impellers should be changed? My boat is in fresh water......Thanks!

[Danny Bailey]

The maintenance manual for the first Cummins 6B I owned said to coat the impeller with silicone spray or silicone grease when installing it new or for long term lay-ups. Silicone keeps the ozone away from the rubber which is what oxidizes it, and keeps the impeller from sticking to the housing and pulling off blades upon start up.

[duchess]

I dont change mine on a regular basis but i keep spares for all pumps on the boat with gaskets etc. if one begins to fail i change it and the other one on the other engine , i keep a kit with the impellors, gaskets . lube etc in my spare parts box under the v berth in my f 36 the kit also includes spare hoses cut to size spare wire set spare racor filters plugs coil,bilge pump belts for both engines etc.