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Topic: 1998 Microphor toilet leak and valve cycling (Read 644 times) previous topic - next topic

1998 Microphor toilet leak and valve cycling

Hey all,

The Microphor toilet in our 1998 u320 4200 started cycling over and over just recently. When flushed, it often just keep flushing again and again. I used the switch in the back to turn it off and checked to see if any wires/connections were loose, but all seemed good.
It stopped doing it, so I chalked it up to a bad connection that was working now.

Just happened again, and continues to cycle. Looking at it in the light of day I could now see that it has also been leaking a very small amount. Upon more detailed examination it appears that the vacuum breaker (from what I found on a topic here :-)) is the most likely culprit. Following directions on that topic I popped the top off the vacuum breaker and find that it is indeed wet under the top as well as down where it is connected to the plumbing line.

I'm guessing that the leaking water might be causing the repeated cycling (two problems occurring simultaneously generally makes me suspect a link), so I'm focusing on fixing the leak first and see if that straightens out the cycling.  In the topic I found here, it's mentioned that the vacuum breaker needs to be removed and cleaned, with the likely cause being hard water.

So the first question is how you remove it.  Am I correct in assuming you just loosen the ring just above the metal plate that the vacuum breaker appears to be mounted on? Any gotchas or steps I should take first? Do I need to remove the entire assembly, or can I take off just the vacuum breaker?
I've turned off the water pump and manifold valve.   

Second question is how does one clean it? Soak it in CLR?

Any suggestions would be appreciated. :-)
James & Susan
Alex & Elizabeth
Tortie and Gigi ( the "Bird TV" cats )
1998 U320 42' Build 5298

Re: 1998 Microphor toilet leak and valve cycling

Reply #1 –
Attaching a picture of the vacuum breaker with the top off.
James & Susan
Alex & Elizabeth
Tortie and Gigi ( the "Bird TV" cats )
1998 U320 42' Build 5298

Re: 1998 Microphor toilet leak and valve cycling

Reply #2 –
Grab the vacuum valve body and turn counterclockwise (looking down from the top) to unscrew. It can be cleaned with CLR and reinstalled with a light coating of silicone grease on the inside.
The toilet is most likely cycling due to a malfunctioning limit switch and/or loose cam that triggers the stop switch.
The selected media item is not currently available.Bob & Faith Rozek
1997 U320 40'
Xtreme Remodel
2010 Scion XD

Re: 1998 Microphor toilet leak and valve cycling

Reply #3 –
I finally got tired of mine and replaced it with a Thetford Aqua High rise china manual toilet.  Uses much less water and works much better.
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: 1998 Microphor toilet leak and valve cycling

Reply #4 –
Same replacement as JohnS, very happy
Tim Fiedler    2025 LTV Unity MBL on Order
2000 Chevy Tracker 2 Door Convertible 4WD Now lifted 4.5"
1985 Citroen 2CV6 Charleston
Murphy Rebel on wheels with 175HP Titan
Cessna P337
1980 48' Westport MY (!/4 Share)

Re: 1998 Microphor toilet leak and valve cycling

Reply #5 –
Quote from: flite2010 –
Grab the vacuum valve body and turn counterclockwise (looking down from the top) to unscrew. It can be cleaned with CLR and reinstalled with a light coating of silicone grease on the inside.
The toilet is most likely cycling due to a malfunctioning limit switch and/or loose cam that triggers the stop switch.

That was very helpful, thank you. :-)

I cleaned it out with CLR but cannot locate my silicone grease. Will pick some up next trip to the hardware store.
It really looked like the ring at the base was the part that needed to turn, but you're absolutely right, the body itself unscrewed from the ring with just hand force. It's possible that it vibrated loose a bit over time and was no longer keeping the O ring at the base of the vacuum breaker body compressed, and that is where the leak was coming from. After cleaning I re-used the O ring as it appears to be in perfect condition. Reinstalled hand tight and I am no longer seeing any leakage from the vacuum breaker (so far), so *hopefully* both of the problems are now resolved. After drying everything and letting it sit this afternoon while troubleshooting, the cycling seems to have vanished for now.

Leaving the top off the back of the toilet, and everyone on the rig knows how to turn it off if it happens again. For now I'll keep an eye on it and see if there is any more leakage and/or cycling over the next couple of days.
James & Susan
Alex & Elizabeth
Tortie and Gigi ( the "Bird TV" cats )
1998 U320 42' Build 5298

Re: 1998 Microphor toilet leak and valve cycling

Reply #6 –
Quote from: John S –
I finally got tired of mine and replaced it with a Thetford Aqua High rise china manual toilet.  Uses much less water and works much better.

Quote from: Tim Fiedler –
Same replacement as JohnS, very happy

Should things continue to become more and more of a PITA we will likely do the same. I'm seeing quite a few Thetford Aqua Magic High rise toilets on Amazon and other sources. Is there a particular model that you have had such a good experience with? Or are they all mostly the same under the hood so to speak?

I like the adjustable nature of the microphor we have atm, it lets me have two settings marked on the fill timer, one for dry camping and one for hooked up. Given the future focus on boondocking capability, if we do decide to replace it we may look at putting in a composting toilet and repurpose the black tank as a grey tank annex. That's a potentially non-trivial job though, so we might opt to just replace the existing toilet with one like you two have. :-)

James & Susan
Alex & Elizabeth
Tortie and Gigi ( the "Bird TV" cats )
1998 U320 42' Build 5298

Re: 1998 Microphor toilet leak and valve cycling

Reply #7 –
The continuous flush is probably caused by the cam slipping. The cam has an indentation on it that stops the flush by tripping a microswitch. May be as simple as tightening the Allen screw. Worse case is the cam is split from overtightening and needs to be replaced. The cam is beneath and to the right of the vacuum break and should be white. Not hard to replace but they don't give them away. I used an epoxy type cement to temporarily patch a split cam I had, while waiting for a new one to come in. The repaired cam lasted about a year.

Roland
1993 U280 4341
2010 Jeep Liberty
The Pied Pipers

Re: 1998 Microphor toilet leak and valve cycling

Reply #8 –
Quote from: Tigratrus –
Should things continue to become more and more of a PITA we will likely do the same. I'm seeing quite a few Thetford Aqua Magic High rise toilets on Amazon and other sources. Is there a particular model that you have had such a good experience with? Or are they all mostly the same under the hood so to speak?

I like the adjustable nature of the microphor we have atm, it lets me have two settings marked on the fill timer, one for dry camping and one for hooked up. Given the future focus on boondocking capability, if we do decide to replace it we may look at putting in a composting toilet and repurpose the black tank as a grey tank annex. That's a potentially non-trivial job though, so we might opt to just replace the existing toilet with one like you two have. :-)
There is a electric replacement I am not sure if it is Thetford or not. It was installed by a PO on my coach, works great
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: 1998 Microphor toilet leak and valve cycling

Reply #9 –
$400 for the part?  That's what drove me to replace the toilet!!
Tim Fiedler    2025 LTV Unity MBL on Order
2000 Chevy Tracker 2 Door Convertible 4WD Now lifted 4.5"
1985 Citroen 2CV6 Charleston
Murphy Rebel on wheels with 175HP Titan
Cessna P337
1980 48' Westport MY (!/4 Share)

Re: 1998 Microphor toilet leak and valve cycling

Reply #10 –
The one JohnS and I have (referenced earlier in the post) is electric
Tim Fiedler    2025 LTV Unity MBL on Order
2000 Chevy Tracker 2 Door Convertible 4WD Now lifted 4.5"
1985 Citroen 2CV6 Charleston
Murphy Rebel on wheels with 175HP Titan
Cessna P337
1980 48' Westport MY (!/4 Share)

Re: 1998 Microphor toilet leak and valve cycling

Reply #11 –
Try 1 (866) 840-4944 for parts.
John Duld
1995 U320C SE 40'