Priming a manual bilge pump

[richardabeattie]

I've just had to strip down and reinstall a manual bilge pump (Chimp Mk 1 but the type is not relevant).
As the pump and the whole run of pipework to the bilge was empty pumping had no effect - the pump is not self priming and the pipes needed to be full. The answer was to pump with one hand and while holding my other hand over the outlet on the outside of the hull. My hand was now a flap valve, the air was expelled and the water followed.

 

[prv]

There should be a rubber flap valve doing the job your hand was, only better.

Our previous boat had a Chimp pump in it, which self-primed just like every other diaphragm pump I've used.

Sure there isn't a bit missing, damaged, or put together wrongly?

Pete

 

[pvb]

I've had a similar problem with a Whale Gusher pump, when the flap valves inside stopped sealing properly. They should be self-priming; after your strip down, did it work properly?

 

[Kukri]

I am old enough to remember “semi-rotary” pumps which were genuinely not self priming - you tipped a pint of water down a funnel to get them started, but once the pump was operating it took less effort than a diaphragm pulp because you didn’t waste energy distorting a sheet of rubber!

 

[lw395]

I've just had to strip down and reinstall a manual bilge pump (Chimp Mk 1 but the type is not relevant).
As the pump and the whole run of pipework to the bilge was empty pumping had no effect - the pump is not self priming and the pipes needed to be full. The answer was to pump with one hand and while holding my other hand over the outlet on the outside of the hull. My hand was now a flap valve, the air was expelled and the water followed.

Seems familiar. A little bit of dust or crud and it won't pump air.
Sometimes pumping very fast works, sometimes not.
Once the pump is wet, it's normally OK for the day.
One trick is to pour some water into the outlet.