Bilge Pump Check Valves

[William Miller]

I'm having problems with my Bilge Pumps.
The floats work and the pumps turn, but often they don't pump.

During my warrantee period, the dealer did a few things, but never really solved the problem.

The pumps are mounted between the stern drive engines.
One about a 1' from the transom and the backup about 6-8" in front of that.
The float for the primary is on a little flay spot on the hull and the float for the secondary is mounted a few inches higher on the stringer.
The primary is switched on the dash and also works automattically.

The outlet hoses run aft to the transom, bend up along the transom and then horizontally above the rear of the engine to the starboard side outlets. My guess is that the lift is about 3 feet.

Both hoses have BLUE check valves mounted vertically in the hose about 1/2 way up the verticle section.

After my complaint to the dealer, the check valves were replaced.
That didn't work and later they drilled a tiny hole (Maybe 1/8") near where the outlet fitting hits the base of the pump.

The problem seems to be that the pumps end up with air trapped below the check valve which might prevent the pump from self priming.
The second theory is that the check valves are getting stuck.
Next is that the weight of the water sitting on top of the check valve prevents it from getting enough head pressure started.

While playing with them (Hose in hand) I have to get 3-4" of water in the bilge. The float will close and startthe pump. I have to manually twist the float down and let it gurgle a bit and then allow the float to raise and start the pump again.
After doing this a few times, it will usually begin to pump as it should and drain the bilge pretty quickly.

So I have several questions:
What are the check valves for?
1. prevent the left over water from washing back in the bilge?
2. Are the outlets too close to the water line so they added these as additional protection to prevent water from siphoning into the boat?

Are the check valves mounted in the right spot?
Could they be removed?

Any other ideas, tips, tricks appreciated.

I'm considering relocating the pumps a little further forward so I can service them easier.
The wires are long enough to get me 6-8".

These are the blue, red and white Rule Pumps.
Is there something known about this problem?

Thanks!

 

[Big Billy]

What I found with the check valves is the pumps don't have enough head pressure to push the water that the check valve has kept in the line. I took mine out and the pump works fine. It does leave more water in the bilge, whatever is in the hose, but that's no big deal.

Bill

 

[William Miller]

Thanks for the reply. Do you think the check valve is just there to keep the water in the hose from back flowing into the bilge or is it for a true safety reason? I recall an older boat that I had where the bilge hose went way up and had a loop in it to help prevent siphoning.

Sort of like the risers on the exhaust manifolds.

Bill, what boat do you have?

Thanks again!

 

[mvoellinger]

Can you try removing the check valves to see if they work without them? If they do, put the check valves in making sure there is no water in the hose from the thru hull outlet to the check valve. This will test the water column creating too much pressure theory.

If they work with the check valves out, but not with them in even with no water, then its that the check valves are too restrictive or defective.

If you can verify they work (try blowing through them each way? Im not sure how much pressure they need to operate) then you have three options - replace the pumps with stronger pumps to overcome them, replace the valves with ones with less resistance (probably easiest if you can find some), or reroute the hoses to not use check valves. The last option would probably involve a loop in the house above the water line to prevent a siphon, but would need to be done carefully (need to look at the height above the water line for the thru-hull output etc)

 

[William Miller]

Thanks,
All good ideas.
Both pumps work fine once they get going.
Part of the problem is that air seems to get trapped in the hose below the check valve and also in the pump while there is water in the bilge.
The bubble of air prevents the valve from "self priming"
The pumps are strong enough and pump very well (past the check valves once water actually gets to them.

 

[douglee25]

I believe the problem is the check valve. To overcome the pressure of the valve, you need a sufficient supply of water. If the pickup on the pump is only partially covered, the pump will not build the required pressure and hence the problem you experience.

Removing the valves should solve the problem but keep in mind, you will have some drain back into the bilge.

Doug

 

[William Miller]

Thanks,
At times, the pump will get totally submerged before it clears the air bubble and starts to pump. Other times, I have to force the float switch up and down a few times by twisting the knob that sticks out. Then it will gurggle burp and start to pump.

Drain back would not nearly be as big a puddle!

 

[jdhatch]

I am glad I found this tread. Maybe it will solve my bilge pump problem that has been addressed 5 or more times since Junuary. I printed it out and gave it to the mechanic.

 

[Scottster]

I just bought my 2004 340 Sundancer a couple of weeks ago. I was down in the bilge this weekend looking around and checking oil levels etc. I noticed there was a blue valve in the aft bilge pump line that goes overboard. The valve was hidden by the blower ducting. The valve was broken in several pieces so I removed the entire thing. I got home and stumbled on this thread talking about the very valve I just removed. Should I replace it or just leave it out? Is there a better valve to install. Any advice? I don't think the more forward bilge pump has this check valve.