Thetford toilet

Submitted: Sunday, Jul 06, 2014 at 12:54
ThreadID: 108622 Views:2096 Replies:4 FollowUps:5
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Hi Guys/ Gals, I,m having a problem with my Thetford model C-402C toilet, in that I can,t get the pump to work. I have power to the circuit board under the push on switch but I think I might have a faulty circuit board as I have 12v power from the black across all other contacts without pushing the button. So I disconnected the board, made up a short lead to power up the pump and I could hear the pump struggle to work. I have had a lot of black scale come through in earlier days when I used that pink stuff to add to the tank. Now I don't use it I don't have as much gunk coming through but the noise I am hearing now is consistent with a pump struggling and I believe it is either blocked with gunk or is there a filter on the inlet of the pump which is blocked. I tried to pull the pump out carefully but it seems to be caught on something and I am afraid of tugging too hard" is there something else I should be doing to get the pump out. I am confident that removing the pump will get whatever is blocking the inlet cleaned up but how to remove it --- please advise!!!
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Reply By: Member - Brian P (SA) - Sunday, Jul 06, 2014 at 13:11

Sunday, Jul 06, 2014 at 13:11
There is a screw to one side of the pump. Remove it and the hose. It should come out now. Cheers Brian
AnswerID: 535523

Reply By: Grumblebum and the Dragon - Sunday, Jul 06, 2014 at 13:17

Sunday, Jul 06, 2014 at 13:17
The impellor on the pump may be jamming with a bit of grit or gunk. Pull off the top cover of the control panel, disconnect the discharge end of the flush pipe where it enters the bowl (beware you need a small hand with 15" fingers to reconnect it - good job for the wife LOL)

Pull out the pump and see if you can free the impellor. If the impellor is free the pump may be stuffed and needs to be replaced. I believe the original impellor from Thetford are expensive, I did hear of someone who bought an identical item from Fleabay for about $10 -15 but I do not have the details.

I replaced my pump about five years ago and bypassed all the fancy control panel stuff - just a 'push to operate' switch beside the old flush button and a simple fuse. Been working fine ever since.

You can download the full workshop manual from Thetford on the net.

Regards John
AnswerID: 535524

Reply By: MEMBER - Darian, SA - Sunday, Jul 06, 2014 at 13:33

Sunday, Jul 06, 2014 at 13:33
Our pump is still happy after 5 years+ (touch wood) but we too had a problem with the control panel. In my view, that panel can't withstand the flexing it gets from pushing the various buttons. Like John, I bypassed the panel and installed a manual on/off waterproof pump switch - easy and simple to operate.... we can do without the waste tank level indicator. From what I hear, pump replacement is common - just another consumable. As for the pink stuff - no use in warm weather (algae) - we now use budget antiseptic from the supermarket (100ml Solyptol etc.) ...maybe 50ml to a tank - smells nice - no gunk in the flush tank..... all has been good on that plan for the last 18 months.
AnswerID: 535527

Follow Up By: Member - Niss42 - Sunday, Jul 06, 2014 at 17:02

Sunday, Jul 06, 2014 at 17:02
G'day Bill.
I have just replaced the pump in my C2 two hours ago.
I think it is the same pump as yours.
Beware of the price $115.00.
Comes out OK but very fiddly to re-install.

Sometimes you can free up a seized pump by trying to turn the impeller with a small screwdriver and a squirt of RP7, worked foe me a couple of years ago.

FollowupID: 819408

Follow Up By: Member - Alan H (QLD) - Monday, Jul 07, 2014 at 09:11

Monday, Jul 07, 2014 at 09:11
I use Napisan in main tank and nothing in the flush tank.

I like to empty every 3 days whether it needs it or not.


FollowupID: 819457

Follow Up By: Grumblebum and the Dragon - Monday, Jul 07, 2014 at 09:38

Monday, Jul 07, 2014 at 09:38

FollowupID: 819458

Reply By: bill m - Sunday, Jul 06, 2014 at 14:42

Sunday, Jul 06, 2014 at 14:42
Thanks guys, got the pump out and sure enough the impeller is seized, so will get a new one tomorrow. I'm also thinking of doing away with the control panel as my only hang up would be no water level indicator, and if I slip up and run the pump dry I'll be up for a new pump. Need to think about it a bit.
Thanks once again for your help.
AnswerID: 535537

Follow Up By: Member - Alan H (QLD) - Monday, Jul 07, 2014 at 08:25

Monday, Jul 07, 2014 at 08:25
I had to replace mine a short while ago. It cost 16.70 pounds posted from UK.

Had a look and these may give you a starting point.

8 litre pump is what you want. I got one and it fitted well so I bought another as a spare.

Trust this will help

FollowupID: 819453

Follow Up By: Grumblebum and the Dragon - Monday, Jul 07, 2014 at 09:42

Monday, Jul 07, 2014 at 09:42
Don't worry about the pump running out of water - it makes a totally differently noise when out of water - so easy to detect. When that happens we just use the flexible shower hose/head as a temporary flush until we refill the tank.

FollowupID: 819459

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