Forward head losing pump suction

[Timm]

1978, 53' YF - I have had the boat about a year now and have not had many opportunities nor the need to get it up on plane. Each time I have done so though, the forward head appears to lose the supply pump prime requiring me to break the discharge connection at the thru hull valve to finally get water flowing again. I can't be sure but I am guessing the hull intake for the head comes out of the water when the boat reaches plane which is causing the system to become airbound.

This a factory Galleymaid system. It appears as if the supply line from the seawater strainer has been replaced. The hose takes a bit of a dip as it comes from the sea strainer (below the level of the strainer) before it goes to the GM pump.

I am wondering when they replaced the hose if it didn't get routed according to the requirements for the system and gets an air lock somehow that the pump can't overcome after the bow comes back down?

Anyone experiece this problem before or have any thoughts?

 

[MikeP]

Our 53s forward head does the same, it will not pump water into the head if it's on plane but when the pointy end "falls" back in the water, it self-primes immediately. There is maybe a 3-4 second delay before water flows into the head on the first flush after returning to the displacement mode.

So it SHOULD self prime without any problem. Obviously an air bubble is forming that cannot be forced out through normal pumping. In our boat the intake hose runs directly from the water intake which is maybe a foot or thereabouts forward of the waste tank, on the port side maybe 18"- 2 feet above the bottom of the "V" to the intake side of the pump. The hose does not have an antisyphon loop which, according to all info re installing heads, it should. But since it works fine, I certainly see NO reason to mess with it. It looks completely OEM but I can't be sure. The pump is located below the water line in the genny room on the port side.

If the entire intake system is below the water line - pump, intake, intake hose, I can't see how it wouldn't self prime but I am no expert re this subject.

 

[Pascal]

i dont' know about GM head but assume that like the water pump they are not self priming. If this is the case, then just like AirCon pumps you need an uphill hose run from the strainer to the pump. If you have high / low points in the line, they will not prime after a haul out (or a run at speed if the intake comes out)

try to re route the hose to eliminate the high/low points.

 

[captddis]

Adding a spring loaded check valve at the intake helps a lot.

 

[Angela]

I never had to reprime any of my GMs after a haulout. Perhaps because they were all located below the water line?