Mike The Red Posted November 13, 2007 Share Posted November 13, 2007 Hello everyone, I have a problem with the vent seal in the cassette of my Thetford C2 toilet, when I try and carry the cassette when it is full, the contents are pouring out of the tiny vent hole! I am assuming the seal has gone. The diagram on the Thetford website is a bit simple and I can not see easily how to replace the seal! I remember seeing a detailed schematic diagram of the insides somewhere but can't remember where. As you have to do this job blind with your hand in the guts of the cassette I would appreciate all the help I can get! any suggestions would be greatly received cheers Mike Link to comment Share on other sites More sharing options...
Terrytraveller Posted November 13, 2007 Share Posted November 13, 2007 Hi Mike, The site you want is link http://www.thetford-europe.com/web/show/id=91559/langid=42 The PDF files cover every aspect of strip down and repair, with excellent photo illustrations. Regards Terry Link to comment Share on other sites More sharing options...
Brambles Posted November 14, 2007 Share Posted November 14, 2007 The vent and seal assembly are a bayonet fit. Turn it anti-clockwise and lift it out. I suspect it may just be covered in crud preventing it sealing. To take the vent assembly apart, press down the plunger and then grip the seal parts and press in slightly and turn anticlockwise gently and pull out. Now this can get crudded up so much inside you may have to work it back and forth, but be careful not to force it. It should come apart easily and force may twist the plastic rod that holds it together and break it off. Watch out for springs. You can off course just replace the whole assembly as a unit. Hope this helps. Jon Link to comment Share on other sites More sharing options...
Derek Uzzell Posted November 14, 2007 Share Posted November 14, 2007 This is something I wrote a while back for a motorhome club magazine: Thetford cassette cleaning – SAVE MONEY! The following method for cleaning ‘scale’ from the interior of toilet cassettes is based on Thetford’s own recommendations. Dissolve 100g of citric acid crystals (available from chemist-shops) in 3 litres of warm water. Pour into cassette, replace spout-cap, leave solution in cassette for at least 5 hours (in fact, the longer the better) tilting, rotating and inverting the cassette regularly so that the acid solution contacts all interior surfaces especially the upper one. This works brilliantly – after a 36-hour soaking the inside of my cassette was just like new, though a couple of scale-related problems remained. My Herald motorhome is fitted with Thetford’s trusty C2 bench-style toilet. Recently, the cassette had started to leak slightly through the Air Release Valve (ARV) (When you stand the cassette on its end the Yellow Press-button object near the base is the ARV.) This was irritating and clearly unhygienic, so I popped along to a caravan dealer for a replacement seal. That’s when I discovered a C2’s Air Release Valve is sold as a complete item comprising plastic body, button, spring and seal-holder (and in my case costing £8.50). Fortunately, having de-scaled the cassette and fitted the new ARV, that leak was cured: unfortunately, the cassette now leaked from the Automatic Holding Tank Vent (AHTV). (This is the other ‘push-down’ thing, nearer to the spout end, that is opened when the cassette is inserted into its locker.) June1993-onwards bench toilets and C200 swivel-bowl models have similar-design AHTVs that are quite easy to remove and take apart (the pre-6/93 AHTV is quite different). Having disassembled mine, I realised that the rubber seal was in excellent condition, but both it and the plastic component it sealed against carried heavy scale deposits. So I soaked all the bits in the same strength of citric acid solution for several hours. With all scale removed the AHTV no longer leaked. I then turned my attention to my original Air Release Valve. At an NEC leisure show Thetford’s rep had demonstrated to me how to take a C2’s ARV apart, but I had always been reluctant to try in case I broke it. Now, with little to lose, I pushed in the yellow button and pulled hard on the seal-holder to free it – sure enough, copious scale deposits on the mating surfaces. After a good citric-acid soak and re-assembly it no longer leaked and I could have saved £8.50 OK, now for some practical advice. If your post-6/93 cassette’s AHTV leaks, it’s worth taking it apart (because it’s easy) for citric acid cleaning. Even if you bought a new seal the AHTV still might leak unless you got rid of all scale where the surfaces meet. I suggest you don't attempt to take leaking C2 Air Release Valves apart, as there is a knack to it. You have to pull the seal-holder in the right direction and there is a fair chance of breaking it. (I notice that the seal-holder in my new ARV is differently made and is marked with a directional ‘bump’.) It’s much safer to remove the ARV, jam the yellow button down (use a couple of strips of wood and some wire) so that the valve is fully open and soak the complete ARV assembly in citric acid solution. ARVs on C200 swivel models have no separate removable housing - you need to shove your hand inside the cassette to pull the bits apart and there is a high risk of breakage. I suggest you try jamming down the yellow button (use your initiative!) and then dribble citric acid solution around it. This will take longer to remove scale than straightforward soaking of the individual parts but should still be effective. As Thetford cassette ARVs and AHTV seals seem to be stock items on most caravan dealers’ shelves I assume that leaking is a common problem. My recent experience suggests that scale-deposit is the probable cause, rather than failure of the actual rubber seals, and that citric acid cleaning will cure such leaks at minimal cost. (Postscript - when I last visited a local chemist’s shop to obtain some citric acid crystals, the pharmacist gave me a searching look and demanded that I tell her why I wanted them. I’ve often wondered what was behind this interrogation, but now I know. Apparently it is common practice for heroin addicts to dissolve the drug in citric acid prior to injecting it. I am now viewing the advice in my motorhome’s handbook to “visit your dealer” in a totally new light!) Link to comment Share on other sites More sharing options...
Mike The Red Posted November 14, 2007 Author Share Posted November 14, 2007 Thanks Derek, I have seen the valve you refer to but the one i have is just a small hole about the size of an old half penny piece, you can see it in one of the illustrations on the link kindly provided above, but the pics on the thetford site are now very clear! I am sure i have seen better somewhere? cheers Mike Link to comment Share on other sites More sharing options...
Brambles Posted November 14, 2007 Share Posted November 14, 2007 http://www.thetford-europe.com/web/show/id=51498/langid=42 Here are the repair instruction on Thetford site. All the pdf files down right had side. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.