# Thetford C3 Cassette not flushing....what to check



## riverboat2001 (Apr 2, 2009)

Hi All,

We only just got our old motorhome the other day (new to us)
It's a 1993 Fiat Ducato AutoTrail Mohawk

The blade was stuck and wouldn't turn, so i took it all apart and gave it a good clean and put olive oil all over the moving parts, left it for a while, wiped the excess off and now it's working lovely.

BUT, the next bit i'm stuck on is that it isn't flushing.

I don't actually have much idea of how it works, as i've reading conflicting web pages about fuses and pumps etc.

As far as i can make out, there is no water tank, so it must draw water direct from the main motorhome tank.

I've taken the cassette out and put a mirror and torch in there and can't see any little black fuse holder, it all looks in very good nick.

What can i check?
Is there a pump with an impeller?
where are the fuses (if any)?

Any help to this newbie would be greatfully recieved.


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## Dick1234 (Jun 15, 2008)

Hi Buddy

I am no expert on toilets but when we had a caravan (around the year of your motorhome there was a hand pump to flush to the side of the bowl? Are you sure you don't have top tank filled from the exterior access door?


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## riverboat2001 (Apr 2, 2009)

No, def no top water tank...!

There are quite a few wires in the area where the cassette sits, so i assumed that they may have something to do with an electric flush


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## sideways (Jun 2, 2008)

pull out the toilet roll holder, the pump sits under there its held down with a screw you can get one at most caravan shops, cut the wires, you join the wires with connectors you get with the new pump and then heat the sleeving with a hairdryer to seal the joint.


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## riverboat2001 (Apr 2, 2009)

sideways said:


> pull out the toilet roll holder, the pump sits under there its held down with a screw you can get one at most caravan shops, cut the wires, you join the wires with connectors you get with the new pump and then heat the sleeving with a hairdryer to seal the joint.


I may be being very thick here, but, as there is no flush water holding tank, i assumed there would be no pump.

Can some ome post a picture of the pump to confirm what it looks like please.

Many thanks for all your help so far


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## sideways (Jun 2, 2008)

some campers flush from the main water tank(mine does) i dont know how to post links but if you Google thetford you should find a picture. its just a small white cylinder with a spigot on one end.


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## Fatalhud (Mar 3, 2006)

There are 2 basic types of flush 
One has its own header tank which is filled either from an external hatch or a filler funnel which is swivelled out above the cassette, This type can have flush additive added and has its own pump operated via the flush switch.
The other type uses the motorhomes fresh water tank to flush, On this type a solenoid (magnetic valve) operates via the flush switch and the drop in pressure kicks in the fresh water pump

Is your toilet a bench fixed type or a swivel bowl type


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## Bobfiggis (Mar 30, 2008)

Hi 

On a C3 the water comes from the main tank.

You don't say if, when you press the flush button, you can hear the pump working in the main tank ( i.e. it's a water supply problem) OR you can't hear the pump (i.e. electrical problem).


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## LeoK (Apr 21, 2006)

Thetford C3 models are connected to the vehicle's water tank.

Once you have established if your problem is with the water system or the electrics you may find that the information available from Thetfords web site is valuable.

There is an owners manual

There are installation instructions 

There is repair information

There are maintenance tips

There is a spare parts list for when all else fails.

Oh, and citric acid crystals (powder) from a supermarket or fleabay mixed with water makes a superb cleaner for the bottom tank. Mix it, pour it in, shake it then leave it to work. 
It doesn't end up smelling of roses, but at least (mine) looked and smelt clean.

Regards ... LeoK


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## riverboat2001 (Apr 2, 2009)

Hi, no mine has no holding tank, and as such must be fed from the main water tank. It's the bench type.

I assume i'm looking under the toilet roll holder.

There is what appears to be a black electrical connecter, with spades on it, this looks snugly connected, could be a relay. Slightly to the left of that there are some hoses. I struggled to get my head at the right angle to see what else there is. I'm going to take a few photos asap and post them on here, but in the meantime, going on the info on the Thetford site:

http://www.thetford-europe.com/web/show/id=51498/langid=42

It doesn't actually mention a pump for the C3, so i had assumed it was gravity fed from the main tank!

However it DOES mention a 3amp fuse and despite using mirrors and a torch, i cannot for the life of me see it.


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## sideways (Jun 2, 2008)

I,m sorry i misled you, the instructions for getting at the pump apply to a bench type with its own flush tank. Obviousl as the O P says without a flush tank the vehicles main pump operates the flush.


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## riverboat2001 (Apr 2, 2009)

sideways said:


> I,m sorry i misled you, the instructions for getting at the pump apply to a bench type with its own flush tank. Obviousl as the O P says without a flush tank the vehicles main pump operates the flush.


Well thats the strangest thing, as my per my previous post. Iassumed it was gravity fed. As the main pump (located in bottom of wardobe) only has 
2 x red and 2 x blue hoses, 1 set each for handbasin and shower, i didn't notice any other hose which would feed the toilet flush .


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## riverboat2001 (Apr 2, 2009)

Gonna try and post some pictures to see if anyone can spot some problems.

This particular bit is just under the toilet roll holder


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## riverboat2001 (Apr 2, 2009)

This is the bit where the blade control slides in underneath. I'm assuming that the little metal sticky out bit is a contact bit that makes sure you don't flush the toilet whilst the cassette is not in.

Again it all looks in good condition


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## riverboat2001 (Apr 2, 2009)

This is the electrical connectors in the cassette holding compartment.
Again, it looks nice and clean and tidy


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## riverboat2001 (Apr 2, 2009)

Model number if it helps


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## erneboy (Feb 8, 2007)

Hello, I know this has been discussed, but we had a Mohawk with a bench type loo and it had a seperate tank for flushing the toilet. I can not remember if I could see the tank but I am sure it was filled from inside the toilet compartment. Of course different builds of the same model do vary, Regards, Alan.


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## riverboat2001 (Apr 2, 2009)

erneboy said:


> Hello, I know this has been discussed, but we had a Mohawk with a bench type loo and it had a seperate tank for flushing the toilet. I can not remember if I could see the tank but I am sure it was filled from inside the toilet compartment. Of course different builds of the same model do vary, Regards, Alan.


Oh, Wow, I haven't found anybody else that has ever heard of this model.
Have you got any info or brochures that you could pass on.

I've got another picture that shows the compartment itself, yes i know it's rusty but i'm going to dig it all out and replace it with something else.


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## Fatalhud (Mar 3, 2006)

Leok has already posted links giving info

Have you located the fuse
it is either a blade fuse or a screw capped 20mm glass fuse


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## riverboat2001 (Apr 2, 2009)

Am i missing anything in here.
There doesn't seem to be any way there is a water tank to fill up


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## riverboat2001 (Apr 2, 2009)

Fatalhud said:


> Leok has already posted links giving info
> 
> Have you located the fuse
> it is either a blade fuse or a screw capped 20mm glass fuse


I've had a mirror in there, i've been on hands and knees poking about, and i've taken loads of pictures, and i cannot see anything resembling a fuse, either blade or glass.


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## Fatalhud (Mar 3, 2006)

It shows it here


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## erneboy (Feb 8, 2007)

Riverboat2001, Sorry, it is over five years since we sold that van. It was our first and we thought it a very fine van indeed. I am afraid any info we had went with it. Just to be sure mine and yours are the same, on ours the habitition door was well to the front and inside it towards the rear there was a swivel armchair. Is that it, Regards, Alan.


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## Fatalhud (Mar 3, 2006)

Hi 
Your toilet does not have a header tank
It does not have a pump

It has a solenoid (the first picture you posted)that operates via a relay when you press the flush 
The drop in pressure starts your habitation fresh water pump using water from your vans fresh water tank

The first job is to find the fuse and check it
Alan H


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## Fatalhud (Mar 3, 2006)

Hi riverboat
I have sent you a PM

Alan H


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## riverboat2001 (Apr 2, 2009)

Fatalhud said:


> Hi
> Your toilet does not have a header tank
> It does not have a pump
> 
> ...


Cheers for all the help, i'm sure we will get there in the end.
1/ The pump doesn't seem to have any hoses going to the toilet, just the handbasin and shower


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## riverboat2001 (Apr 2, 2009)

Fatalhud said:


> It shows it here


Yep, i downloaded that page too.
It says its for C2 version 1, perhaps i have a different version.
After looking at the attached pdf and this picture, you can see that i don't have anything down the left hand side of the sliding area for the fuse to be.

It's totally smooth....there is no fuse there


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## riverboat2001 (Apr 2, 2009)

This is another close up showing that there is no fuse holder there


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## Fatalhud (Mar 3, 2006)

Did it flush before you worked on it
Have you got water in you fresh water tank

Try unscrewing the pipe feeding the solenoid to check for water

Alan H


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## riverboat2001 (Apr 2, 2009)

Fatalhud said:


> Did it flush before you worked on it
> Have you got water in you fresh water tank
> 
> Try unscrewing the pipe feeding the solenoid to check for water
> ...


don't know, think we were very niave and took sellers word that it worked.
And we didn't know the first thing about motorhomes.
At least we are learning how they all work, going to stand us in good stead when on the road and something breaks :?

Definately got loads of water in the tank


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## Fatalhud (Mar 3, 2006)

Are there cables at the back right :?: 

If so the fuse should be around there

Alan H


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## LeoK (Apr 21, 2006)

Hi again riverboat2001

So, lots of water in the tank and, obviously, the main pump is working.

You have accesd the 'flushing water valve', where the electrical connections look good.

Can you hear the valve operate when the flush button is pressed ?

Have you access to the flush button electricals ?
Are there volts available ? If so, do they get to the actuator of the water valve when you press the button.

Probably a red herring, but I discovered that the electric controls of our C2 didn't work unless the correct switch was 'on' at the zig controller. Turned out that the toilet electrics shared a fuse with an equipment which I did not expect. Made oursw work by switching the right switch. Could your problem be that simple ?

If there are no volts to the flush button and / or the flush vater valve you are still looking for an electrical solution.

If there are both volts and water at the flush valve it's time to remove the valve and give it an internal clean.

Please keep us posted on you progress.

Regard ... LeoK


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## Bobfiggis (Mar 30, 2008)

The pipe on the left of your photo 242 is the supply pipe. Follow it back and you will find it will branch off the cold water supply pipe to the washroom tap somewhere - probably in the cupboard under the basin.

You still haven't told us if you can hear the pump working when you press the flush so I'm still not clear if it is an electrical (fuse ?) problem or water supply (air lock?)


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## riverboat2001 (Apr 2, 2009)

Bobfiggis said:


> The pipe on the left of your photo 242 is the supply pipe. Follow it back and you will find it will branch off the cold water supply pipe to the washroom tap somewhere - probably in the cupboard under the basin.
> 
> You still haven't told us if you can hear the pump working when you press the flush so I'm still not clear if it is an electrical (fuse ?) problem or water supply (air lock?)


nope, no pump sound at all


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## Fatalhud (Mar 3, 2006)

Do you have a volt meter :?: 

Alan H


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## riverboat2001 (Apr 2, 2009)

LeoK said:


> Hi again riverboat2001
> 
> So, lots of water in the tank and, obviously, the main pump is working.
> 
> ...


Hi, thanks very much LeoK

I'm really sorry, but as far as testing for volts and electrics etc, thats out of my league 

Water in tank, main pump working fine, don't think we have a "zig" unit, but all switches under the bunk are on.

Going to have another root round when hubby gets home from work in about 2 hours.

Fatalhud, has kindly offered his phone number to talk us through checking all the points to check.

I have thankfully got a "contact" who eats and breathes campers, but i can only get in touch with him on Fridays....so i am determined to have a real go at checking all that i can.


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## riverboat2001 (Apr 2, 2009)

Fatalhud said:


> Do you have a volt meter :?:
> 
> Alan H


If i had one, i wouldn't know how to use it 

I'm going to try and get my mechanic to teach me how to use one, but trouble is he's always so busy....Still there's always google and youtube!


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## igglepiggle (Nov 7, 2007)

hi riverboat dont know if i miss some think. if u have push down flush .
under neath is a mico switch + have u turn on all switches on control panel


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## riverboat2001 (Apr 2, 2009)

igglepiggle said:


> hi riverboat dont know if i miss some think. if u have push down flush .
> under neath is a mico switch + have u turn on all switches on control panel


So if i unscrew the flush top, there is a micro switch below, yes, but 
a) how do i reach the microswitch?
b) nothings gonna drop off the end and get lost is it?


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## LeoK (Apr 21, 2006)

*Thetford C3 Cassette Toilet*

Riverboat,

Please dowmload and print the Thetford spares for C3 file.

It is not an engineering drawing but it does give a pretty good idea of how the parts of the C3 fit relatively to each other.

Page three represents the toilet unit 'out of it's box' and turned upside down. The black item 57, shown above a corner of the upper 'blob' is the fuse holder cap. In the installed toilet this will be at a corner nearest to you and will point up, rather than down. When you find and unscrew it the glass fuse should drop into your hand. It should be a three amp fuse.

Alternatively, yours may have the three amp blade fuse indicated as item 58A (see the circle with detail also on page three). This, alternative, fuse would be fitted, from below, into item 52 (the saddle). The flushing switch is also within item 52 but is not shown in place on the illustration. You will need to remove the switch cover (56) to access this fuse and the flushing switch.

I suspect that item 52 (the saddle) may be rotating below the housing when the Flush Knob (12) is turned to open the blade. This raises the possibility of broken strands within wire 55, which would prevent the flush from working when the knob (12) is pushed down. Sorry but you will need a meter to check that.

As before, download the repair instructions for ...

The Flush Knob removal and refitting.

The Switch Cover removal and refitting.

The Switch removal and refitting.
and
The Elecric Valve removal and refitting.

These instructions have pictures which help to understand exactly what you have to do.
It's well worth downloading the whole set to make your own 'handy' service manual. (I now have the C3 set on my computer and I don't even have a C3).

Please keep us posted. Regards ... LeoK


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## chrisjrv (May 7, 2007)

Hi,
for the attention of the dripping loo man, griffly 16?


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