Peggy: The forward head pump in our Beneteau 393 was replaced late last season by the dealer. It seemed to work OK and I winterized it by pumping potable antifreeze through the inlet thru-hull into the holding tank and also out the discharge thru-hull. This season, it seems to work OK when I pumped clear water out the discharge thru-hull, but when I pump into the holding tank, I get back pressure pushing the handle up after I'm done. The seat cover in the 393 covers both the bowl and the handle so I've been leaving it down to hold the handle down. Over an extended period, the pressure seems to dissipate. Could it be a clogged vent to the holding tank? I opened the pump-out, but there seemed to be no built up pressure and it didn’t relieve the pump back pressure. Could it be the diverter valve? I'll have to check this weekend for the gurgling sound of water flowing into the holding tank. If it is the valve, how difficult is it to change that out? Any advice would be appreciated. Fred
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Problem has to be downstream of the toilet
If something were wrong with the toilet, it would happen when you're flushing overboard too. And I think you've narrowed it down to the two most likely culprits--tank vent or y-valve. Tank vent is the first thing I'd check...'cuz while opening the pumpout cap would relieve any major pressure, the discharge fitting is at the bottom of the tank...covered by the tank contents. So it would take a lot of pressure to push air in the tank above the surface out the vent. Check the vent thru-hull and vent fitting on the tank. If that's not it, it's either the y-valve or a clog...and I'm betting on the y-valve--especially if it's a Jabsco. 'Cuz the "valve" is actually just a very flimsy little "gate" that the handle moves from one outlet to the other..if a bit of TP or something you've eaten (apple seed, watermelon seed or even smaller) gets caught under it, it can jam it...it may only be able to slightly open to the tank side. It's not hard to open up to check it and clean it out if necessary.
If something were wrong with the toilet, it would happen when you're flushing overboard too. And I think you've narrowed it down to the two most likely culprits--tank vent or y-valve. Tank vent is the first thing I'd check...'cuz while opening the pumpout cap would relieve any major pressure, the discharge fitting is at the bottom of the tank...covered by the tank contents. So it would take a lot of pressure to push air in the tank above the surface out the vent. Check the vent thru-hull and vent fitting on the tank. If that's not it, it's either the y-valve or a clog...and I'm betting on the y-valve--especially if it's a Jabsco. 'Cuz the "valve" is actually just a very flimsy little "gate" that the handle moves from one outlet to the other..if a bit of TP or something you've eaten (apple seed, watermelon seed or even smaller) gets caught under it, it can jam it...it may only be able to slightly open to the tank side. It's not hard to open up to check it and clean it out if necessary.
It appears to be the Joker Valve
I cleared the vent with a hose as you suggested, but was still getting the back pressure and some gurgling blowback. My good friend Rudy had had a problem with the Joker Valve on his Jabsco, and sure enough, when we removed it, the valve was inverted (pushed through and facing the pump rather than the hose. We pushed the valve through the right way, reinstalled it and it seems to be working well -- no back pressure, no gurgling.
I cleared the vent with a hose as you suggested, but was still getting the back pressure and some gurgling blowback. My good friend Rudy had had a problem with the Joker Valve on his Jabsco, and sure enough, when we removed it, the valve was inverted (pushed through and facing the pump rather than the hose. We pushed the valve through the right way, reinstalled it and it seems to be working well -- no back pressure, no gurgling.
Joker valves don't turn inside out by themselves..
It's the back pressure that turns joker valves inside out, Fred. And it takes a LOT of backpressure to do that, which you prob'ly relieved by clearing the tank vent. If you didn't, it'll build up again...and enough backpressure to turn a joker valve inside out is also enough to crack a tank...or--if you're lucky--just an eruption in the bowl that rivals "Old Faithful." So a reversed joker valve is only a symptom that something downstream of the toilet is pushing back, hard! That you were able to clear the vent and/or remove the discharge fitting from the toilet without an eruption only means that the pressure was able to escape through the reversed joker valve...so keep the vent clear. 'Cuz next time, you may not be so lucky.
It's the back pressure that turns joker valves inside out, Fred. And it takes a LOT of backpressure to do that, which you prob'ly relieved by clearing the tank vent. If you didn't, it'll build up again...and enough backpressure to turn a joker valve inside out is also enough to crack a tank...or--if you're lucky--just an eruption in the bowl that rivals "Old Faithful." So a reversed joker valve is only a symptom that something downstream of the toilet is pushing back, hard! That you were able to clear the vent and/or remove the discharge fitting from the toilet without an eruption only means that the pressure was able to escape through the reversed joker valve...so keep the vent clear. 'Cuz next time, you may not be so lucky.
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