Master Head Gulping Air

[JLR]

My master head evacuates faster than it fills. It is a fresh water fed Gallemaid setup. Because it flushes faster than it fills, it takes a big gulp of air which requires a bit of burping to get it to evacuate again. Not a stator issue as she flushes just fine until she empties the bowl and sucks air in from the empty bowl. Is there any way to increase the fresh water flow rate or decrease the flush rate. Not a big deal but ther should be an easy answer. Local wrench has suggested closing the discharge sea clock a bit to slow the flush rate. That does not seem like the right answer. Any ideas?

 

[MVCaprice]

I have a similar issue with my master head. It sucks dry when I am running. I suspect it may be a scupper issue which I will need to check at the next pullout.

I have also noticed on occasion that the fill rate exceeds the evacuation rate. Have you tried using white vinegar in the line? Perhaps there is a buildup?

 

[MVCaprice]

My master pump is outboard of the starboard engine and the thru hull is right below it. Is your boat configured the same way?

 

[JLR]

It is a fresh water fed head. The pump is outboard of the starboard engine.

 

[dottieshusband]

You probably already know this, but the pump has 2 rotors and stators, the big end and the little end. The little end draws the water from the tank or thru hull. Mine are raw water, so this might not apply to yours. Mine sometimes get air bound. I open the bleed screw on the small end and listen for a rush of air and replace the screw as water begins to flow. If there is no water, then there is a blockage somewhere. I've actually had a fish impaled on the thru hull grate before. If I've got good water flow, then I close the thru hull valve and remove the small end of the pump to check the rubber.

 

[Pascal]

It sounds like you re not getting enough water in. Start with the simple stuff first like a kinked hose or a partially closed shut off valve.

As to the advice you received to partially close the discharge sea cock, this woudlnt do anything since waste goes to the holding tank... Stay away from whoever gave you that ridiculous advice..

 

[saltshaker]

You probably already know this, but the pump has 2 rotors and stators, the big end and the little end. The little end draws the water from the tank or thru hull. Mine are raw water, so this might not apply to yours. Mine sometimes get air bound. I open the bleed screw on the small end and listen for a rush of air and replace the screw as water begins to flow. If there is no water, then there is a blockage somewhere. I've actually had a fish impaled on the thru hull grate before. If I've got good water flow, then I close the thru hull valve and remove the small end of the pump to check the rubber.

I'd agree with this. Your water supply isn't adequate for the discharge. Do you have a separate pump for the FW supply or are you still using the supply side of the Galley Maid pump?

 

[Plan B2]

From the troubleshooting guide at raz:

The pumps are designed to evacuate more that is brought in, 7 GPM in and 10 GPM out.

Sucking some air is normal. I would first verify sufficient intake.

 

[JLR]

Thanks all.

Jack - I do not have a separate water pump for the fresh water side. It is being fed by the dockside water connection and controlled by a solenoid valve as far as I know. I suspect it is not involved with the GM pump at all--at least that is what I think. When underway, it is being fed by the fresh water pump.

Jim - I will check with Raz and ask for advice. You are correct. Most of my other heads also suck air but none of the other heads has as long a run to the pump as the master head.

 

[doc g]

John , there really are two ways to set up fresh flush, one is to use the flush side of the pump and feed the fresh water via a solenoid to the flush water side of the pump. Another is to bypass the flush pump and just go straight to the head with the fresh water . The latter is the way I did mine on my old boat but I put 1/4 turn ball valves inline to regulate the incoming water. I would check and see if there is a valve somewhere to control the flush water coming in........Pat

 

[JLR]

Thanks Pat. I suspect that I have the latter as well. I do know that on another head, the solenoid got stuck open a few years ago and without flushing the head, the water kept coming in. I'll check for a ball valve near the solenoid. Also, I spoke to the Raz folks. They said to check to see if there is a short clear crossover hose on the back of the head itself which is supposed to vent any air. I do not recall seeing one but I will check. Pat- do you recall where the solenoid for the master head is located--in the removable panel at knee level just before you get to the master? That assumes you have the layout with one master head vs. his and hers.

 

[MikeP]

It sounds as if the system is operating correctly - the output pump MUST evacuate more water than the input pump can supply. You wouldn't want it to be any other way!

Frankly, although you said it Isn't a stator problem, I think it could be - either bad stator or rotor. OR, if the input pump won't immediately pick up water, there could be some restriction in the input side.

 

[JLR]

there could be some restriction in the input side :

how about low dockside water pressure?

 

[doc g]

John,
What I was talking about was on my old (61CY) boat not the 74 SD I have now. I mounted the FW flush solenoid on the aft stb ER wall . I also set it up so you could just put the stators back, reconnect the RW flush hose and go back to RW if need be. Not sure where it would be on 74. I have the Headhunter heads on mine... Pat

 

[JLR]

Pat - thanks. I should be able to check it out more fully this weekend.
Mike - I am not sure how it could be a stator/rotor issue if it discharges fine and the intake stator is not used (I guess) since it is a direct fresh water feed. I am nhot saying it is impossible, I just do not understand it.

 

[dottieshusband]

My Galley Maids also used to "burp" but it turned out to be unrelated to waterflow. As mentioned in another post, there should be a little air equalizing line between two PVC elbows on the head. If it clogs, you'll get a big burping issue. I removed the line, cleaned the fitting with a piece of copper wire and put a new piece of vinyl tubing back on. Sometimes it is the simple things!

 

[MikeP]

I failed to note that you are not using the input side of the OEM GM pump. So, as you said, the input stator/rotor could not have anything to do with it.

 

[JLR]

Unfortunately, the back of the head is within a box. That box is wallpapered around and sealed. Although the box can be lifted, I am not inclined to mess up the entire wall on the hopes of finding a clear hose that if it exists, may be in need in cleaning. I am annoyed that the back of the head is basically, inaccessible. So, I need another way to skin this cat or learn to just burp the head using the silver button, as needed. I saw no vented loop in the ER for this head. Recall that the pump itself is basically inaccessible as well, and this was confirmed by Bruce Morrison who believes, as do I, that the issue is the gulping of air when flushing. So, at present, my choices are to mess up the wall, or cut a new hatch in the ER to provide better access to the pump, neither of which I am inclined to do. Any ideas would be greatly appreciated.

 

[MikeP]

That simple clear piece of tubing between two fittings on the back of the head is often the cause of the burping you are describing. Our master head did that and it DOES have the fitting/hose. I could even see water running through the tube so I ASSUMED that wasn't the problem. However, as has been described, when I removed the tube and cleaned out the fittings with a piece of stiff wire, the burping stopped. So if the tube/fittings aren't completely clear, the head may burp.

I understand that you don't want to change anything to get easy access to the back of the head and the pump but I think you should just bite the bullet and do so. With something like a Fein saw, it's pretty easy and not even very messy to cut an access panel.

I have found that cursing a lot while doing such work is very helpful.

 

[JLR]

Thanks Mike. Cursing helps a lot. I think I might just leave it until it gets South and then put the knuckle buster in the hands of my folks down there. The head works fine as long as you know to burp it with the silver button. As long as it is fixed before the Admiral uses it down South, I am okay. Sure wish I knew whether it had the clear hose.