Holding tank hose or vent plugged?

[Bernie Soostmeyer]

I had our holding tank pumped out today and noticed that the usual suction sound from the toilet bowel was absent and the waterlevel in the bowel lowered very slowly after the tank was empty. Tank indicator showed empty, whereas before it showed full and the clear vacuum hose showed flow indicating that the tank is empty. I have noticed that the pumping action changed somewhat intermittently during the last several dozen uses. Instead of an even force resistance in the up and down pumping strokes there is a springiness in the downstroke action which disappears when holding down the handle. Water in bowel stays clean and waste gets pumped into tank although slowly. I recently lubricated the pump with a squirt of cooking oil. Its hard to imagine that this would be a plugged vent since the whole tank volume would be in compression. Any ideas?

 

[Peggie Hall/HeadMistress]

My guess...

If your tank vent were plugged, you wouldn't be able to empty the tank. In fact, unless the tank vent can't allow enough air into the tank during pumpout, there shouldn't be any hissing in the toilet bowl...that's a sign that the tank is trying to get air from any source it can BECAUSE it's not getting enough through the vent.If your toilet is a Jabsco manual, I suspect the wet/dry valve has failed--a VERY common problem in Jabsco toilets...it hangs, creating backpressure when you flush. The cure: a replacement wet dry valve. Pouring anything down the toilet to lubricate the pump is a never ending battle...because anything thin enough to be poured down the toilet just washes out in a few flushes. If you want to do it right, and only once a season as preventive maintenance, buy a tube of thick teflon grease (Super Lube is the best), remove the screws that hold the top of the pump on and remove the top, put a healthy squirt of grease in the pump...pump a couple of times to spread it all over the inside of the cylinder...put the top back on...you're done. Takes all of 10 minutes. Or, you can pour something down the bowl every week or two and rebuild the toilet twice as often.