Tecma head overfilling

[Rocky Lou]

Just recently, I’ve noticed that after flushing the head, the bowl will overfill. It normally doesn’t fill pass the rim but stays at a level substantially higher than before. The indicator light is green so the holding tank is not nearly full. Anyone encountered this issue?

 

[BO-J]

On my 2018 R-27 it was the Joker valve that was cruded up, a 10 min job to replace and all was good.

 

[Rocky Lou]

Just recently, I’ve noticed that after flushing the head, the bowl will overfill. It normally doesn’t fill pass the rim but stays at a level substantially higher than before. The indicator light is green so the holding tank is not nearly full. Anyone encountered this issue?

Thanks, I read about joker valves in some earlier posts, however, the Thetford manual makes zero mention of 'joker', only calling out: Solenoid Valve and Lower Discharge Check Valve. Since this is the first time I've had to deal with this sort of crap (sorry), I have no idea which it is and, surprisingly, the Thetford manual has no part numbers. I presume you had to pull the the unit since both parts are located behind, and I don't know if that is included in the 10 mins. Although, as you can tell, I won't be breaking the record if I do it.

There's a YouTube vid. on changing a Tecma pump, but could find nothing on jokers.

If I could get a p/n and a bit of guidance on the replacement, I'd take a shot.

~Paul

 

[scross]

We experienced similar symptoms in our Dometic electric flush toilet last year. Take this with a grain of salt because it’s a different boat with a different toilet.
First repair was a new joker valve. That didn’t solve the problem. Turns out the hose from the toilet to the black water tank has a flat 7 foot long run. Over 12 years solid sediment (think rocklike sediment) filled up the hose and restricted the flow. New hose and problem solved. Talked to several sailboat owners who said it was a common problem after several years when the discharge hose has a flat run like our R-25 Classic.

 

[BO-J]

Here is a link to parts list, for the head you should have.
Parts under 10 have the joker valve included it is part 38866 - 38867 straight check valve or 90 check valve.
The Joker valve is the same in both, and you can most likely get the joker valve separate if you have the old one in hand, at a good marine store. They are fairly common.
https://marinesan.com/tecma-thetford-wi ... s-drawing/

 

[BO-J]

Here is a YouTube video that will get you to the joker valve. And beyond.
https://www.youtube.com/watch?v=jUokqayVUJU

 

[fishheadbarandgrill]

I would try rebooting your controller. Turn off your house batteries for 5 minutes and then try it again. Thedford customer service has been helpful for me in the past when troubleshooting head issues as well.

 

[Ralf H]

Hi Rocky,

Pretty good answers already posted here, but I will add to the chorus in mentioning that I would check the joker valve first (the check valve) That one is usually the problem with most backfilling issues. Looks like the parts info and solutions for further diagnosis have also already been posted. Hope this helps but let us know.

Cheers,

Ralf

 

[Rocky Lou]

Thanks for all the helpful replies. It appears that joker/check/duckbill valve failure is a common issue that I plan to look into. I appreciate the videos/parts list from user: BO-J and suggestion to do a reboot from user: fishheadbarandgrill

I also emailed directly with Ralf and understand that if the valve is still in good shape, you can simply clean and replace. I don't trailer so I'll be working in the slip and need to be sure the raw water intake is well closed before disconnecting any hoses.

My plan is to:
- Try the reboot and see if has any affect
- R/R the joker valve
- Report results

Unfortunately, while most toilet vendors sell only the valve, Thetford requires that you purchase a complete assembly, either 38866 or 38867, straight or right angle, in order to get joker valve. I spoke to them by phone to confirm.

 

[NwRecon]

You told us the problem.

Just recently, I’ve noticed that after flushing the head, the bowl will overfill. It normally doesn’t fill pass the rim but stays at a level substantially higher than before. The indicator light is green so the holding tank is not nearly full. Anyone encountered this issue?

Now add if the water in the full bowl has any color and if there is any odor? My understanding is the joker valve is a one-way waste solution valve. It is designed to let waste fluid and solids into the the holding tank and stop the back flow from the tank to the bowl. If it gets "gunked up" some fluid will be able to return to the bowl but it would have a color to it and an odor(especially if you are using any waste tank treatment).

If the fluid in the bowl is clear and has no odor, i doubt the joker is the problem.

Does the bowl fill while docked, motoring or cruising? Fresh or sea water flush?

 

[it4llc]

FWIW, I had a similar problem with the water backing up some and overfilling the bowl, which turned out to be the joker valve. There wasn't any odor and I wasn't 100% sure it was backflowing. I think the main reason was when we flush, I try to make sure everyone does a good flush to get all the waste all the way to the tank, so what was backflowing was the water left in the line below the high point in the line. I suppose one way to troubleshoot for sure might be to add some coloring to the water (that isn't waste). There was a prior thread on this, when I think Brian may have suggested that if you so change the joker, to make sure you flush very well, and potentially empty the tank, flush and empty again, so anything that comes out when you change the joker is as clean as possible.

 

[Rocky Lou]

Now add if the water in the full bowl has any color and if there is any odor?

In my case, we have color and odor, and I can also confirm unhappy wife.

 

[NwRecon]

Here is my other thoughts. If you take a three gallon bucket and drill a hole in the side near the bottom, sit it on a small chair, add a hose the same size as the waste hose to tank, run it about four feet to a five gallon bucket and install a 90 degree fitting in the end of the hose and hook it over the lip of the five gallon bucket. Support the hose to keep it level or a slight down hill slope. Now poor water into the three gallon bucket and watch as it will not back up unto the small bucket. Now add a block in the hose or at the fitting and you will see water back up into the small bucket but it will only fill up as you add more water. So, use your own bucket to measure one gallon at a time and poor it in the toilet bowl. If it backs up just the amount you poor in, you have a clog, not a back flow problem from the waste tank.

The joker valve could be stuck closed with junk buildup but you should be able to use a plunger to push it open and then clean with a chemical that does not cause rubber or plastic to swell, then flush flush flush with water.

I can see getting a full bowl if you have a clog and flush three times quickly, but that is not a back flow problem. Also as the water sits in the bowl it will cause a slight bit of pressure just due to the weight of about two gallons of water and then slowly seep through the slits in the stuck joke valve or through the clog. Come back in 15 minutes and all looks fine again. I guess you could take the toilet apart and manually clean the joker valve but I don't think you will need to replace it unless it is eaten up or deformed and then you would see back flow especially when your holding tank very full or you have a clog down the line towards the tank.

 

[BB marine]

I replaced the joker valve once a year after owning the boat for two years. Replaced three times in 5 years. I had fresh water flush which increased the life expectancy but I did not want to deal with a Joker valve failing while we were doing extended cruising. I would agree that the issue could be a Joker but I would go one step further to confirm that the tank vent is completely clear too. The joker valve is a rubber check valve with no moving parts. It relies strictly on having no back pressure to seal. If the tank vent is partially plugged or completely plugged each time you flush the waste tank builds pressure. If the pressure can not be relieved through the tank vent it will find the path of least resistance and sometimes that is the head. The Joker valve if at all fouled or hardened from salt water scaling will allow the waste to back up because of the tank pressure.

My point, sometimes the back flushing of waste is a combination of a marginal joker valve and a partially plugged tank vent line.Replacing the joker fixes the issue but only partially. When I replaced my Joker valve I would first do a complete waste tank cleaning. Flushing several times with fresh water. If you have a macerator I recommend using it after going to a pump out and flushing to confirm all waste is removed. Then do a continual flush several times using your macerator. This insures the system is well cleaned and exercises the macerator pump at the same time. Remove the vent hose at the hull fitting and attach a hose to it running fresh water through it to back flush it to the waste tank cleaning it and confirm good water flow so you know it is not restricted. Make sure the hull vent is free flowing with no restriction. Now replace the joker valve. There will be some back wash that leaks into the head as the hose is removed but because of flushing several times the water will be clean. Replace the valve and your troubles will be gone.

 

[NwRecon]

BB, I have seen photos of a waste tank install sent to me from RT and it looks there is a 90 degree fitting on the waste supply hose at the top of the tank. Do you know if there is a tube that drops down in the tank part way from the fitting or once it make it past the fitting is it just a free fall to the bottom of the tank or the level of waste in the tank? If it is a free fall, it is hard for me to understand how the waste from the tank can easily get back into the feed line unless the tank is full or very close to full. I can understand how a blocked vent would try to push the waste back up the feed line after a few flushes reaching the tank to build up pressure without being able to vent air out. If the vent was clogged, I would suspect problems during pump-outs since a higher volume of air would need to enter through the vent to the tank because of the high suction of waste out of the tank.

 

[BB marine]

BB, I have seen photos of a waste tank install sent to me from RT and it looks there is a 90 degree fitting on the waste supply hose at the top of the tank. Do you know if there is a tube that drops down in the tank part way from the fitting or once it make it past the fitting is it just a free fall to the bottom of the tank or the level of waste in the tank? If it is a free fall, it is hard for me to understand how the waste from the tank can easily get back into the feed line unless the tank is full or very close to full. I can understand how a blocked vent would try to push the waste back up the feed line after a few flushes reaching the tank to build up pressure without being able to vent air out. If the vent was clogged, I would suspect problems during pump-outs since a higher volume of air would need to enter through the vent to the tank because of the high suction of waste out of the tank.

It is free fall, the tank fitting on the waste tank in my C26 ( 30 gallon) stuck down about 1 inch. the fitting is 1/2" OD to match up with a vent hose that is 1/2 ID. To the best of my knowledge I have never had the waste tank 100% full but I know it has been within 2" of full several times while cruising. So I guess you're thinking is correct (Close to full) a 30 gallon tank is used to hold 30 gallons of waste. When cruising this capacity can be a limited capacity . We do not go to a marinas to pump out until we need to when cruising.I have had the vent restrict on my boat a few times even with being proactive. I assumed that some of the waste is floating in the tank and as I am cruising it sloshes around in the tank. The telltale for me is when removing the deck cap there is a slight amount of pressure that bleeds off. I have seen some boaters take the deck cap off and the pressure release causes waste shoot out of the deck fitting. The vent is normally blocked at the tank fitting or crud restricted in the low portions of the vent line. The only time I have seen the hull fitting restricted is from insects building nest. You are also correct that when pumping out it would be difficult to get the waste to pull from the bottom of the tank if the vent is plugged. I have heard some folks at a pump out say " the pump out doesn't work well " then I use it and it works fine for me. I Wonder Why? My thoughts are maybe their vent is plugged! In my years of working on boats you would be surprised at how many times I have fixed head and waste tank issues by flushing out vent line hoses that are kinked or plugged with _ _ _ _ . The biggest culprit is toilet paper wads. Most of the issues are the plumbing related not the head itself.


I'm just adding thoughts from my experiences.

 

[NwRecon]

I like BB's thoughts on flushing the head several times to clean the joker valve and line to the tank after pump-out and before second pump during tank rinse. Running a few gallons down the pump-out fitting helps to rinse the tank and line. Rinsing the vent is also a good idea also IF YOU DO NOT HAVE A VENT FILTER. I don't have one and did consider installing one, but mine would be installed inline behind my refrigerator that I would need to remove to service. I have decided to NOT install a vent line odor filter so I can back rinse the vent line from the outside during my pump-out procedure especially since my 2018 R23 has no waste tank level gauge or view sight window.

I plan to use the business half of an old outboard muff to attach to the fresh water hose so it will seal over the vent fitting on the outside of my boat. That should allow a good enough seal to push any TP or solid out of the vent fitting or line. I envision being able to use while on the water with the factory wash-down hose if on an extended cruise and a vent problem rears it's ugly head. Thanks for your experience and idea BB.

 

[Rocky Lou]

I have a 90° Joker valve on order. I removed the bolts holding the toilet into position. I also removed the clamps from the top of the joker valve unit and the bottom, 4 clamps. The problem I’m having now is removing the joker valve unit since it appears to be glued into a female PVC pipe that runs to the black water tank. It’s the final step for removal and then replacement with a new unit however it’s really stuck. Anyone have this problem or suggestions how to get it out? Only thing I can think of is to cut the bottom of the joker valve where it connects to the PVC.

 

[Rocky Lou]

I'm done for now but removing the Joker value was the 'job from hell', largely because of steps taken during the installation of the head. Here is what I encountered:
- The 90 degree Joker assembly was 'welded' into the white hose (female) than runs to the black water tank. Long story, but, my mechanic buddy, who owned an automotive business for 40 years and has removed every possible stuck hose, tried all his special tools and found that if you inserted any tool with force, the white hose cracked and there is not enough hose to cut it off. The joker assembly and hose bonded and I expect were epoxied together.

- We were then left with unscrewing the joker assembly, which should be a very easy procedure. However, in this case, we confirmed that someone had epoxied the two pieces of the assembly together. We had to saw, piece by piece, and pull the top part of the assembly off. I scraped off loads of brown glue, then, we replaced the joker value and top assembly onto the base unit. IT IS AMAZING THAT SOMEONE WOULD GLUE PIECES TOGETHER THAT WERE OBVIOUSLY DESIGNED TO BE SEPERATED. Once we had the two assembly pieces open, we ran lots of water directly into the black water tank to insure the line was clear. Instead of gluing them back together, we applied a dielectric silicone to make it easier to disassemble next time. We ran many leak checks and all was dry.

Of course, we could have tried removing the line from the black water tank. However, that was likely bonded and glued as well, like the connection at the head. I would then have to replace the entire hose.

While I'm glad to have a working head again, this job was vastly more difficult than it needed to be.

 

[NwRecon]

Well good news it is working now Rocky. Could you see any differences between the old and new valve? The last guy I talk with did not see much wrong with the old one but while there replaced it anyway. A lot of people seem to jump right to the joker valve since it is often easy to replace and talked about a lot. I assume once you received the new valve you had a better idea of what needed to be done to replace the old one. Thanks for the update.