On my boat I have a Vacu-Flush system. I have a forward and aft head. The pump will pump ait out of the system, then when you press on the flush pedal this breaks the vacuum and pulls the waste down the pipe, then the pump takse over and pumps the waste into the tank. The it keeps pumping until a sensor tells the pump to shut off and the system has vacuum for the next flush. First the issue was the system was bleeding down every few minutes, thus turning on the pump.
I had to buy a special vacuum gage. I started at the pump and disconnected the hose. Yep crappy, smelly job. The pump held the vacuum. I was also replacing the rubber line as it was hard and most likley over 20 years old. Then back up the line I took the hose up line from a "Y" pipe on the aft head line. At this point is where the aft and fwd head come together to a single line to the pump. I checked the vacuum and it checked good. This tells me the fwd head is good and the leak is in the aft head. As I was putting it all back together, I crack the "Y" pipe and had to order another.
Once I received a new pipe I installed new hose from the outlet of the vacuum tank to the "Y" pipe. The next test is at the inlet of the vacuum tank. This tank also hold the shut off sensor. It checked good and the pump shut off. Vacumm was held for several hours. So the leak is ether in the 30' of hose to the aft head another horse shoe pipe or the base of the head. When I went to reconnect the hose to the vacuum tank, I had cut it too short! Uggggggg. This will suck as I would have to remove the line that runs some 30' from the aft head throgh the engine room to the tank under the galley floor. Off to West Marine and bought 30' of new hose. This is the same time we were having 26f nights and 30f days! The pipe is hard and not pliable.
Kay helped me pull the new line which took about 3 hours. She came up with an idea to soften the line by heating it with our buddy heater. It worked! Then I could get the line to lay flat in the engine room! Ugggggg again! Kay suggested that I start the engines and heat the engine room up! Great idea sweetheart. It worked.
I hooked up the hose to the vacuum tank and tested the line at the aft head. Checked good. Then I installed the horse shoe pipe, tested and checked good. Installed the base of the aft head checked good! Well then I guess the original leak was in the 30' of hose. Installed the head bowl and then system was tested and operates as advertized.....Below are some pics.
Aft head with hose removed and horse shoe pipe
Aft head bowl
Old 30' hose and yes it was cold outside
Installing new hose through engine room
Heating the end to soften the hose
Vacuum testing new aft hose
Vacuum testing aft head lower base
Before installing bowl, there are two rubber gaskets this is the first or thin gasket. Notice the notch?
Second rubber gasket. This is the thick one and aligned with notch. You can see the different color between the first gasket (grey) and the top one (black)
Installing bowl centering over flush ball
New bowl clamp. Per the instructions, the tabs go on the front with a gap in the back.
Holds water? Good to go.
Adding the blue stuff
Ready for use....