Bilge Pump

[Guest]

At the end of last season we took on a fair amount of water due to blocked cockpit drains whilst not onboard. The bilge pump didn't work when we got there and hence we assumed we needed to service it. Having removed it and tested it at home it works absolutely fine....which is puzzling us.

Has anyone any ideas as to what could be wrong? Air block, debris (not likely as the hose end has a filter attached to stop this),....???

All ideas appreciated.

Richard

 

[Guest]

Does the hose loop up above the pump? This could cause airlock. Does the pump need priming when you test it at home? This is unusual for a bilge pump as they are normally self priming, but it could be the case.

 

[Guest]

If the inlet/outlet valves are old/losing flexibility they may not be making a seal against the pump body. This can especially be the case when a pump hasn't been used for some time. There may also no water in the pump to help with making the seal. Can be temp cured by priming with some water but it's worth stripping the pump and checking the valve flaps to see if they are resting against the pump body or have hardened and perhaps curl away from their seats. Quite cheap to replace.

 

[Guest]

Richard, you don't say what 'activates' the pump. Most bilge pumps are very robust and its the switch that activates them that becomes the problem.

There are a number of different switch types. If you have an all-in-one pump and switch you will find that it will have either two sensors (which activate when the water flows over them both) or a mercury tilt switch.

Both types give problems. The sensor type get covered with bilgex or oil/diesel and lose their sensitivity and the float switches get small items caught in them.

As you have the system stripped out I suggest you contemplate having the pump and switch separate. Put the pump somewhere accessible for cleaning and maintenance and go for an air activated micro switch in the bilge. (Par make one)

 

[Guest]

Re: Switches

I assume it has a tilt switch. Its NOT been wired in AFTER the battery isolator switch has it? (Obvious but ive seen it done).

 

[Guest]

You mentioned that you took it home.

Could it be that the wiring connections had corroded enough to break the circuit. Then when you took it home the action of disconnecting and reconnecting (for test) was enough to make contact again?

Bilges being damp/wet are prime areas for this type of corrosion.

Suggest you make sure that ALL the wiring is in good condition.

The previous owner of my boat had it sink (8 hours) at mooring. As a result I learned the lesson and I have TWO bilge pumps each connected to separate batteries and one battery connected to a solar panel.

 

[Guest]

Re: Switches - Tilt or Sonic type?

If its a tilt, the circuit is easy to test - put a multimeter on 20volt range across the Pump connectors (or rig a 12v bulb if no meter) then hook a wire under the tilt switch and lift it. If the light lights, or meter registers 11v or more the pump should work! If no light/volts either tilt switch or wiring is open circuit.

If its a sonic switch you will either have to put water in the bilge to test the auto side of it, but you can test the rest of the circuit with the manual override switch. (You should have a manual override switch wired across the tilt switch also).

 

[Guest]

If the pump motor is "on the way out" it might operate when at home with no head to lift the water, but fails when there is back pressure caused by trying to lift the water any height.

Switches - Johnson pump switches have a small magnetic float inside an enclosed housing. when the magnet rises it operates an electronic switch. No environmentally unfriendly mercury! not much chance of fouling by bilge rubbish.

johnson pumps available at www.yachtbits.co.uk

 

[Guest]

Richard, Is your pump protected with a fuse? If so have you checked it? This could explain the pump working at home but not on board! Good luck, BarryD

 

[Guest]

I should have said a little more,clearly that the pump is unfortunately 100% manual! Hence no fuses, electrical connections or the like.

We'd wondered if it cold be as simple as an air bubble in the pipe...?!?

 

[Guest]

Check instructions.

Does it have to be primed first ?

Is the line from bilge to pump too long?

Is there a hole in the line from bilge to pump?