How do you remove the manual pump assembly from the water flush tank on a Thetford caravan toilet unit ?

.There are a few different installation manual available through Thetford Download RV Product Manuals Support Portal Thetford
follow this link and select your specific model to download the manual you need.

problem is there is an RV for your system. you will need to do the following.
Drain all holding tanks, fresh water and sewage

1. Attach garden hose to fresh water fill and fill tank.
2. Turn on pump switch and open cold water side of all faucet/ shower fixtures. Leave open until water runs clear. Repeat for hot water side.
3. Flush toilet until clear water runs into bowl.
4. Dump tanks again.
5. Sanitize water system. use a water sanitizer
6. If a water filter is installed, drain lines, remove filter assembly, clean and reinstall with new filter.
7. When ready to use the water heater, turn by-pass valve to open position to allow water to enter and fill the hot water heater tank.

Here is a link I found to help you. I have fixed a few and replaced some for various camper and motorcoaches but not having it in from of me make it difficult to diagnose. This link gives a list for many issues.
http://howtomendit.com/search.php?keywords=thetford

this link is for the manuals available from Therefore.
http://www.thetford.com/customer-support/product-manuals/

There should be plugs underneath the camper to drain the water tanks. Remove them and let the water drain. There should also be a plug on the water heater, remove and let water drain. There is also a bypass valve on the water heater to divert water away from the heater, turn this to bypass. After the water has drained replace the plugs except the water heater plug. The heater plug can stay out. Fill fresh water tank with RV antifreeze, usually about 3 gallons or maybe a little more for larger RVs. Run pump opening faucets one by one till water is forced out and the antifreeze flows including toilet. When antifreeze is flowing out the faucets close faucets and shut off pump. When pump is shut off open faucets, the antifreeze may get slushy in very cold conditions but wont freeze and a little may drip out of the faucets. The water heater may still have a small amount of water in it but shouldn't be a problem if you leave the plug out. Make sure the blackwater and greywater tanks are empty, you can dump a little antifreeze down the drains and toilet to make sure the sink traps are free from water and the blackwater tank has antifreeze in it. Other than that just shut the propane tanks off and youre done. Try to leave a couple of windows cracked slightly to promote airflow and reduce condensation inside the camper

Keystone's have two water drains under the outside stairs unscrew those and most of the water will drain. once those have drained add your antifreeze to you fresh tank and run you pump. then make sure you add it to all drains. Do not for get to to unscrew you hot water drain. Very big socket.

ok, been a while so lets ee if I can get this all down.

1 - Drain water from your holding tank and remove drain plug in hot water heater. Drain holding tanks ( Waste )
2- turn on bypass for hot water heater ( instruction if needed )
3 - Get yourself some winterizing fluid ( can't remember exact name ) from your local Dealer . 2 or 3 gallons should be good
4- Poor this fluid into your water rez tank. All of it
5 - now go around to EVERY tap in your trailer ( one at a time ) and turn on cold water until water runs pink ( or what ever colour fluid you bought ) Close faucet them do the same for hot water tap. Repeat this at every faucet. Even the ones outside if you have any.
6 Don't forget to flush toilet in water runs pink.
7. Ensure all gas vales have been turned off ( tank vales included )

If you did everything right you should be good to go.

Plz double this list to make sure I covered everything

Pull bottom plug out of hot water heater tank let all water drain. Then open all water tank drain valves and be sure your RV is tilted so it will drain towards the valve. Go in RV access water heater valves put it in bypass so no antifreeze can enter water heater tank. Pump RV antifreeze with hose provided into all water lines throughout RV by turning on your main water pump after you have stuck the bypass hose in a new and full antifreeze bottle, then flush toilet until red antifreeze comes out. Open all faucets one at a time until red antifreeze comes out. I use 3 gal but some only use one, the more the better it’s cheap at Walmart. Don’t forget to run outside shower until red antifreeze comes out also, very important or it will crack in the cold. Finally make sure black and grey tanks are empty and flushed at your last camp trip before winterizing. Pour antifreeze in toilet and all drains making sure first that black and grey tank shut off valves are pushed in and closed. Get a quality cover and store RV, it makes a huge difference on protecting roof and roofs lap sealant! All RV antifreeze is non toxic and you just drain it all at your first camp stop after winter! Note: don’t forget to put water heater ionizer drain plug back in wrapped with new white Teflon tape and take water heater valves out of bypass! Draw a diagram of regular mode and winter bypass mode so you don’t forget especially hot and cold water heater blender valve between the two MUST be shut off after you unwinterize
or you will cool your hot water unwanted and have no hot water to use! Happy Camping folks!

There will be a couple of valves located on the drivers side of the unit. One will be a wide valve, 3", and the other will be a narrow valve, 1-1/2". The wide valve is the black water dump valve. Make sure you are connected to a dump station, open the valve and allow the waste to flow out. You can purchase a tank flush wand that will aid in the flushing of the tank. You connect it to a water hose and insert it into the tank through the toilet and flush the tank with the valve open.

Connect the trailer to the city water supply, turn on the water and open each faucet until clean clear water is present. Don't forget the toilet and outside shower if equipped. Next reinstall the anode rod (suburban) or drain plug (atwood) into the water heater. Go to the back side of the water heater and close the valve on the pipe that connects the cold (bottom line into water heater) and hot (upper line out of the water heater) and then open the bottom cold water line valve and, if equipped, the upper hot water valve. This will fill the water heater. Open the hot water valve at the kitchen faucet. When the water flow is steady the water heater is full and ready for use. If the unit is equipped with a water filer, after all is flushed out, turn the water off and remove the filter housing. Install a new filter and re-secure the housing and turn the water back on. If you are using the fresh water pump, it is possible that the winterizing valve for the pump was left open. If so, close that valve which will divert the pump back to drawing from the tank.

Contact your local service center directly or online here