Tolet flap stiff

[hallii]

It's a CS200 I think, I bought a spare cassette "just in case". In France a week ago I had a small leak on one of the seals so I switched to the spare cassette. It is very stiff when operating the flap opening lever, operation when not fitted is fine, the valve opens and closes smoothly and easily.

 

I tried lubricating the seal with olive oil and that helped a bit but it remains stiff, so stiff my wife cannot operate it!

 

My "normal" cassette is easy to operate.

 

Any ideas?

 

H

[Alanb]

Hi,

 

Just offering a thought based on the mechanics of the mechanism.

 

Do the bowl and cassette line up correctly when viewed through the bowl?

 

I am wondering if there is some misalignment between the end of the operating lever, and the rectangular top of the knob on the cassette, as would be the case if the cassette was either too far in, or too far out, or even sideways misalignment.

 

If for whatever reason the above is the case it would make the combination stiff to operate, while the individual components function OK.

 

Alan

[witzend]

hallii - 2017-10-04 8:20 PM

operation when not fitted is fine, the valve opens and closes smoothly and easily.

 

Do you mean the toilet bowl flap opens and closes easily when not fitted or the new cassette

 

A new cassette would be dry and stiff with it half full of water put in some liquid soap turn it upside down and give it a good shake don't spare the lube around the control for the flap

[Alanb]

Another suggestion. Is the sliding flap on top of the new cassette jamming? You could check this by removing it. It is not an essential component.

 

Alan

[Derek Uzzell]

The attached photo is of a cassette for a Thetford C-200 toilet,.

 

When the yellow knob (with the gloved hand on it) is rotated, this opens or shuts the ‘flap’ in the top of the cassette. Closing the flap involves two stages, with the flap initially moving sideways beneath (but not contacting) the cassette’s rubber lip-seal and - when fully under the lip-seal - finally moving vertically upwards. Opening the flap is vice versa - the flap first moves vertically downwards until it is clear of the lip-seal, then moves sideways.

 

With the cassette removed from the cassette locker, it should take little effort to manually rotate the yellow knob so that the flap is opened/closed.

 

If the knob on the old cassette can be manually rotated easily, but the knob on the neew cassette is difficult to rotate, the stiffness problem lies with the cassette.

 

If the knob on the new cassette can be manually rotated easily when the cassette is out of the locker, there must be a conflict of some sort between the new cassette and the toilet’s mechanism that links the operating lever to the cassette’s yellow knob.

 

(The plastic piece that slides across the top of the lip-seal when the cassette is extracted from the cassette-locker, although not essential to the toilet's operation, does have a useful purpose. Water will collect inside the lip-seal above the 'flap' and the 'slide' prevents this water from coming out if the cassette is carried by its handle. And should the cassette's opening/closing knob be accidentally rotated so that the flap opens, and the cassette has waste in it and is carried by its handle, the slide should stop the waste pouring out. I polish the underside of my cassette's slide to ensure it's moves easily across the lip-seal.)

[hallii]

Thanks all, I have lubricated the seal well and it made little difference, as mentioned, if the flap operating knob moves freely when not fitted then there must be some sort of alignment problem when inserted..

 

It slides in easily although the last mm or so needs a bit of a shove to engage the latch, but then that's the same with the original cassette.

 

I will check alignment and if all is OK I think I will swap the flap seals over. I wonder if the new seal is a bit to thick.

 

H

[Alanb]

hallii - 2017-10-05 10:06 AM

 

It slides in easily although the last mm or so needs a bit of a shove to engage the latch, but then that's the same with the original cassette.

 

I will check alignment and if all is OK I think I will swap the flap seals over. I wonder if the new seal is a bit to thick.

 

H

 

I cannot see why the lip seal could be the cause of the problem, as it is quite flexible and engages wiith the bottom of the bowl, and the flap valve.

 

Your statement that its a bit of a shove to engage the latch, set me thinking. I have previously suggested possible incorrect alignment in the X, and Y directions, but what about Z - vertical direction.

 

When looking over the top of my in situ cassette with the aid of a torch, I can see what I think is about 1mm of clearance between the operating fork, and the knob on the cassette. I think that a lack of any clearance here could give rise to your problem.

 

You could perhaps compare your two cassettes in this respect.

 

Alan

[Derek Uzzell]

I agree with Alan’s view that the lip-seal should have no effect on how difficult it is to operate the toilet’s ‘flap-opening’ lever.

 

Is the new cassette the latest design with wheels and an extendable handle? If so there’s the potential for the type of alignment problems Alan mentions.

[hallii]

The cassette is the old type, no wheels etc. I will be having a careful look at the clearances and alignment when I get a chance, just back from France and the lawn took all afternoon to make it look like a rough hay field!

 

I can appreciate that if there is pressure exerted on the operating fork and "button" it could make it bind.

 

I should get time tomorrow to have a look, the ironing can wait :-)

 

H

[hallii]

SORTED! The new cassette has a different vent valve, the original has a "vent to outside" fitting the new one has just a simple vent.

 

The valve was catching on something on the operating arm, you can just see the rub mark.

 

Thanks for your help, it was indeed a problem of things not fitting and interference etc.

 

Now I need a new valve.

 

H

 

[Derek Uzzell]

H

 

Thetford’s ‘outside-vent’ option for C200 toilets not only involves fitting an automatic pressure-relief valve that differs from the standard valve, but (as will be apparent from the link below) a different operating ‘arm’ must also be installed.

 

http://www.jacksonsleisure.com/caravan-and-camping/toilets/cassette-toilets/thetford-outside-vent-for-c200-cassette-toilets/

 

The solution in your case is to replace your new cassette’s standard automatic pressure-relief valve with the type of outside-vent automatic pressure-relief valve fitted to your original cassette.

 

http://tinyurl.com/yawvxy23

 

If you don’t do this you’ll be risking damaging your toilet’s operating mechanism when you use your new cassette.

[hallii]

Derek Uzzell - 2017-10-06 4:21 PM

 

H

 

Thetford’s ‘outside-vent’ option for C200 toilets not only involves fitting an automatic pressure-relief valve that differs from the standard valve, but (as will be apparent from the link below) a different operating ‘arm’ must also be installed.

 

http://www.jacksonsleisure.com/caravan-and-camping/toilets/cassette-toilets/thetford-outside-vent-for-c200-cassette-toilets/

 

The solution in your case is to replace your new cassette’s standard automatic pressure-relief valve with the type of outside-vent automatic pressure-relief valve fitted to your original cassette.

 

http://tinyurl.com/yawvxy23

 

If you don’t do this you’ll be risking damaging your toilet’s operating mechanism when you use your new cassette.

 

You are (as usual) right Derek, the mechanism is fouling the standard pressure relief valve and that is what was making the lever stiff to operate. When I bought it I trial fitted it and it seemed OK, I didn't try opening the flap though. Anyway, new bits ordered and on the way. The flap opening bit (bright yellow) has a seal that has worn, hence the slight leak. The seal must cost at least 10p to make, but I have to buy the complete gubbins, I will make sure the new one is lubricated with some Vaseline, might last a hundred years :-)

 

H

[Derek Uzzell]

Petroleum grease (eg. “Vaseline”) can damage natural rubber. Although the seals used on Thetford cassettes are likely to be made of synthetic rubber - that should not be harmed by Vaseline - you’d be better to use silicone grease just in case. (example here)

 

http://tinyurl.com/y9f3vul2

 

As the blade opener rotates, the seal will be vulnerable to wear, but other cassette seals that do not involve rotation (eg. the seal on the automatic vent valve or on the air-release push-button) can start to leak due to scale buiding up on the surface of the ‘faces’ that the seal contacts and on the seal itself. Treating the leaking component and the contact-faces with a citric acid solution to remove the scale will often cure the leak and avoid buying a replacement component.

[Derek Uzzell]

The Thetford C200 automatic vent-valve mismatch issue has in fact come up before

 

http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Thetford-C200-cassette-query/42059/

 

The benefit of the C200 ‘outside vent’ kit is that, even if the cassette-locker is not properly sealed from the motorhome’s interior, stinky odours should not enter the vehicle’s living area.

 

My 2005 Hobby motorhome’s cassette-locker had yawning gaps that led directly into the shower compartment and the resultant smell inside the vehicle was soon evident. To combat this I chose to seal the cassette-locker properly and fit a SOG ventilator. Hobby buyers must have complained about the smell as Hobby 2006 models were fitted with the C200 ‘outside vent’ option with the vent-hose leading to an outlet in the cassette-locker door.

[monique.hubrechtsgm]

As most motorhomers have on thetford and dometic.Have a clear view on a explosion 3d diagram. And how to reach the seal. Ask the brands how to do it. And praise the lord the progress on improvement to get away from this agony and have a inttelligent tank system for a week or so.

[monique.hubrechtsgm]

As long we have it : keep it clean inside the tank cassette of about 20 ltr. By cleaning vinegar and hot water. or a mixture of soda poudre, called caustic soda. and let it stand in different upside- down posiions for a day. Unscrew the bajonet sliding top and inspect the result. Thetford is some degrees of the sliding main seal disc. dometic is not turning.They are factory assembled whit silicone based grease which is a must to have if you maintain a motorhome. Check the mainseal for flatness in his recess to keep the O/C flap easy to operate. Dometic recommend to this every month on heavy duty. And renew the fill water tabs afther 4 days .