How to Repair A Scamp Toilet (Dometic 711-M28)

How to Repair A Scamp Toilet (Dometic 711-M28)

IMPORTANT — make sure to order the correct flush ball / spring cartridge / shaft kit for your toilet. I was originally given incorrect information on the type of kit, and the black faced cartridge in this video should not have been used for my Dometic 711-M28. I was told by Dometic a toilet with a metal lever has to use a white faced spring cartridge and toilets with all plastic pedals use a black faced spring cartridge. The spring cartridge cams are placed in different locations depending on color which will affect rotation. Additionally, the plastic shaft has been switched to brass for better wear. Here’s the kit I switched to after this video.  This is an essential tool which makes the job much easier.

When placing the seals on the toilet, make sure the cutouts on both seals are stacked on top of each other (the lower seal saying “This Side Up” and both stacked seals are aligned with the cutout on the toilet base). Also, the screw on the metal clamp band should be at the very back of the toilet (otherwise, there is a risk of seepage).

What happened to our toilet?
Our 2020 Scamp 13’s toilet has worked really well until very recently.  Two days into the start of a twenty day trip up the California coast into Oregon, the flush ball stuck on our Scamp’s toilet.  The white plastic ball is the main barrier between the toilet bowl and the black tank which sits below (preventing odors from coming into the bathroom).  The flush ball opens when the flush pedal is depressed (which also causes water to be released into the bowl simultaneously).  In the past, lubricating the seals around the ball with silicone has worked well to get it moving again after being stuck.  This time though, the ball was really stuck and I put a rubber glove on and forced it open.  Unfortunately, this resulted in the ball becoming completely inoperable.  We made it through the rest of our trip by plugging the hole at the base of the ceramic toilet bowl with a rubber toilet bowl plunger (saving us from having to cancel the trip).  This solution worked really well, but was only temporary.

What Else Can Go Wrong?
According to the Dometic parts list, there are 23 parts to the 711-M28 model toilet.  So, there are a lot of possible points of failure.  However, the usual culprits of toilet problems are a cracked water valve (results in leaking toilet), broken spring cartridge and/or rotor shaft (results in flush ball not opening/closing), and a dirty or damaged flush ball and/or bowl seals (results in flush ball not opening/closing, water not holding in bowl).  Dometic has a handy trouble shooting guide on page 6 of its handbook.

How can these issues be repaired?
Fortunately, it’s not impossible to trouble shoot and take apart the mechanisms of this toilet.  And, parts can be ordered online.  I’ve created a step by step video showing the disassembly of the toilet.  Often, just the first few steps will be necessary if one just wants to clean or replace the seals (flush ball seal and bowl seal) between the toilet and the base (e.g. for when the toilet bowl stops holding water or the flush ball becomes stuck).  To repair other parts though, the flush pedal cover and mounting screws may need to be removed to provide access to the water valve, spring cartridge, rotor shaft, and flush ball.  Make sure to dump and flush the Blank tank and turn off the water supply when working with the toilet.  Note:  be careful not to overtighten metal clamp (just tighten until snug and toilet bowl is secure and stable).  If the clamp is too tight, the flush ball may be compressed too much against the seals and the flush ball may get stuck, water may leak out of the bowl and/or the plastic half clamps may crack.

How to diagnose what’s wrong?
In addition to reviewing Dometic’s trouble shooting guide, the company has great customer service and will be happy to assist (800-321-9886).  Our issue was a little strange (inverted flush ball) and we were referred to a local tech center.  The guy who answered the phone was extremely helpful and answered all my questions.  In the end, no one really could explain how our flush ball became inverted.  The advice was to get the Flush Ball & Shaft Kit and replace the flush ball, rotor shaft, and spring cartridge.  After this repair (as documented in my video) everything worked great!

How to prevent toilet issues?
First, always keep water in the toilet bowl when travelling (except when driving) to prevent odors from coming up from the black tank and also to keep the seals between the toilet and its base from drying out.  Additionally, since one of the most common issues is the toilet flush ball getting stuck and/or the toilet bowl not holding water (e.g. water drains quickly into the black tank even though the flush ball is closed), a good preventive solution is to use plumbers grease and toilet seal lubricant regularly between trips to keep the seals from drying out and the flush ball moving smoothly.  One of the first signs of trouble is if the toilet bowl can’t hold water.  As noted above, water is important in the bowl because it keeps black tank odors from escaping.  Additionally, water draining from the bowl when the flush ball is closed can indicate dry or dirty seals or even damaged seals.  Before taking the toilet bowl off its base though, try using plumber’s grease and toilet seal lubricant (as shown at the end of my ten minute video).  If that doesn’t work and the toilet still can’t hold water, then remove the toilet from its base and try cleaning both seals (or replacing the seals if they appear damaged).  The company says the seals can last 15-25+ years, so it’s likely the seals will just need a good cleaning with soap and water and a toothbrush.  It is recommended to occasionally remove the seals between the base and the bowl when not holding water.  Soak them in warm water with a little dish soap to loosen any calcium scales, iron deposits or dirt build-up.  Let dry, then spray very lightly on both sides with silicone.  Note:  put seals back in same position with notch in the 4 o’clock position and the seal that says “This Side Up” under the black seal.  Also, make sure plastic half clamps come together at front of toilet bowl (they will have a gap at the back) and make sure the metal band screw is at the very back of the toilet (at the gap of the plastic half clamps).

Helpful items:

Toilet Seal Lubricant
Thetford RV Toilet Seal Lube & Conditioner

Plumbers Grease
Slik Seal Plumbers Grease

Dometic 711-M28 Toilet Parts:
Flush Ball & Shaft Kit:  Part #385318162
Genuine Dometic

Dometic Seal Kit:  Part#385311462
Genuine Dometic
Generic Version

Water Valve Kit:  Part#385314349
Genuine Dometic
Generic Version

Disclaimer:  You will get the same great Amazon price by clicking on the links here compared to buying directly on Amazon, but by buying here you will also be supporting the continuation of this website as we get a small commission from each sale.  These are products and procedures we use for our own Scamp that we selected and developed from our own research and experiences.  However, we do not endorse any specific product and cannot guarantee that the products we use are exemplary and the procedures we use are complete, accurate, detail the correct recommended procedures, or apply to your model small travel trailer.  It’s always best to double check with your manufacturer or operation manuals to ensure you are doing everything correctly.