Jabsco toilet backflow from tank into bowl

[Jimongee]

Suddenly we have occasional air bubbles and waste flowing back into the toilet bowl. The lever for dry bowl or wet bowl still works perfect. I closed the thru hull just to make sure raw water wasn't siphoning in. No change. I suspected a spider clogged tank vent next. It was a bit restricted, but after correction-I still have the problem. I'm 100% comfortable dissembling and replacing what ever, but if anybody has had this ocurr and figured it out. I'd appreciate your tips. Thanks

[a64pilot]

Joker valve is my bet.

[BjarneK]

I had the exact same thing happen to my two Jabsco toilets. I took the pumps apart, carefully removed all the calcium buildup, and lubed the valves with heavy grease. The grease was important to make the joker valve work well. No problem since.

[GordMay]

Check out “Diagnosing backflow ...”
Here ➥ Jabsco Tech - Let's Solve Water Supply Problems

[rgravitte]

I had the same thing happen a couple of months ago. Changing the joker valve fixed it.

[topmast]

Besides the choker valve there's the flopper in the base of pump unit. Leak back can happen if it dosen't seal. Calcium lumps, string, crud. even the riveted weight can fall off .When occasionally adding veggie oil ,a dab on the extended shaft helps to O ring.

[jamesdavis]

Had the same problem. I bought the entire pump assembly off Amazon for $52 (free shpg.) I did not have the pump with the lock-down handle and wanted that as well as no fuss replacement having bought the boat recently. Replacement took about 40 minutes.
I went by the video Gord's link pointed to...Jim

[Seadoc777]

Took out my Jabsco four years ago and installed an Air Head composting toilet. No problems since and no smell perfect solution.

[Jimongee]

Thank you to all who provided the helpful info
Jim

[thinwater]

a. If there are bubbles coming back, that suggests a clogged vent. If they don't have a way to get out, no joker valve will stop them. Blow it back into the tank with a water hose. A failed valve will NOT cause bubbles, since the gases will go up and out the vent.

b. We're all assuming the hose dumps into the top of the tank. Thus, the waste is just in the hose. Flush enough strokes to move the waste all the way to the tank, then a few more to blow most of the clean water through. There should be little waste in the hose. This is different than flushing a home toilet; when the bowl is MT you are not finished. I believe this is explained in the instructions... which we all read, right?

c. Use a Raritan PHII joker valve. It fits perfectly in your Dometic manual head and last 2-3 times longer.

[YellowcakeMan]

I had the same symptoms from a one year old system. After taking the whole thing apart, it turned out that the joker valve had become deformed. Who knows why. I'd try putting in a new Joker before you troubleshoot further.

[boeing1]

I agree on the joker valve, also be careful what you use to clean the toilet, some cleaners can ruin the joker valve

[thinwater]

Leakage = bad joker valve and probably poor flushing procedure. Poor hose routing can contribute.

Bubbles = blocked vent. Why else would bubbles force their way up through the water trap? They would not.

Deformed joker valve. There are several possibilities:

• Someone used a plunger. This will turn them inside out. Unlike household toilets, they can't flow backwards.
• It was installed sideways. The lips need to be vertical. Otherwise, they sag over time.
• Back pressure due to blocked vent. See "plunger."
• Flushed something that you shouldn't have, including many bowl cleaners and some additives (anything containing formaldehyde).

I've done a lot of head testing. Too much. I would replace the joker valve (it's probably due), but I would expect contributing factors. It is probably not just one thing.

[jamesdavis]

Any idea as to which cleaners might be the best.?

[SouthernPride]

Move the swirl control switch from North to South then back again.

Depending on where you are boating the centrifugal equatorial magnetic forces will cause a reversal swirl of toilet water creating the bubble action you are referring too.