Replacing Thermostatic cartridge -temp control housing stuck

[Phil the Fluter]

I'm attempting to replace an ultra SASF2 – M thermostatic shower cartridge but, having removed the temperature control knob from the housing that incorporates the temperature 'stop' mechanism, I cannot pull this housing free from the rest of the assembly.
I can see no circlip holding it in position but it simply will not be pulled away from the main assembly.
Using a screwdriver as a lever, I can rock it slightly moving it may be 2 or 3 mm at the top – but it will not move further.
What can be holding it in position?

 

[Knappers]

Looks like it's pretty well cemented onto the spline.
Maybe try a big socket that just fits the hole and a tap with a hammer to break the bond with a bit of a shock?
Might need cutting off....
You could pull it till it breaks and replace it if necessary?
If I was to cut it off I think I'd use a holesaw about the same size as the hole to remove the bulk of body and then a multi-tool to get what's left off the spline...?
Good luck!

 

[Phil the Fluter]

Thanks, Knappers,
I've managed to pull and prise it off. The silver (outer) part came off first but left the rubbery centre section still stuck firmly in place but I then managed to pull and prise that off too. Hooray!
I've removed the circlip holding the flow control in place but, unfortunately, the flow control too appears to be firmly stuck.

 

[Phil the Fluter]

Good news, Knappers! I've managed to get the bl**dy thing off!
As you suggested, the housing for the temp control was expendable and so, if I smashed it to bits, it wasn't the end of the world.
However, the flow control handle and housing are not available anywhere these days and suppliers say there is no suitable alternative - so that meant that, if I smashed it during my attempts to remove it, it was game over for the whole shower unit.
Luckily (I'm almost tempted to say 'miraculously'), after a bit of very careful and relatively gentle pulling and prising, it came off'
Many thanks for your help. Apart from the practical advice, it's great to have somebody supporting you when you're very much a non-plumber and struggling with a job like this.

 

[Knappers]

Thanks & Well done persisting. I know the feeling when your pulling on something and wondering if there's a grub screw or something you've missed.
The main body actually looks OK.

 

[Phil the Fluter]

More problems!
I removed the 3 bolts but the cartridge was stuck fast into its housing. After some prising and pulling, it finally came free.
I offered up the new cartridge but it wouldn't go completely into the housing, and remained sticking out by about 1/4 of an inch. No amount of wiggling would make it go in completely.
I removed the new cartridge and decided to see how easily the old cartridge would slip back into place.
To my surprise, it wouldn't go in completely. It went in, all but the last quarter of an inch.
After some turning and wiggling, I found that if I put the top bolt hole in the 9 o'clock position, the cartridge would slip forward and fit properly (almost as if it were keyed, which it isn't).
I then spent a lot of time trying to get the new cartridge in but no amount of turning and pushing will get the last quarter of an inch to move forward so that it fits flush with its housing.
The problem isn't the back end of the cartridge assembly (the spring and temperature sensor) because I've tried leaving those out and trying again with the main cartridge body – but still it won't go in all the way.
The interior of the housing looks perfectly clean – no corrosion – and I can't see any blockages whatsoever.
I note that the bolt holes in the new cartridge are a different shape from those in the old but, otherwise, the two cartridges look almost identical.
I've sent the attached photographs to the supplier to ask if they are in fact identical (for all practical purposes) and they have just replied saying that the two cartridges are the same.
Any ideas?

 

[Ben-gee]

The new one on the left looks shorter if anything, but I guess this is due to how much the temperature splice has been rotated.
Make it as short as possible.
Make sure all o-rings are properly in their grooves.
Grease up the o-rings with silicone grease, that bottom one looks quite proud of the brass and so could be very tight when new.
Then, if you’re sure there is no keying, push it in. Use the bolts to draw it fully home if necessary (tighten them down gradually in sequence- by which I mean don’t fully tighten A then B then C ; rather tighten A a bit then B a bit then C a bit, then back to A etc etc)

 

[Phil the Fluter]

Hello Ben-gee. Many thanks for your interest and your advice.
1. You're right about the two cartridges looking different lengths in the picture and, again you're right about it being due to the rotation of the 'cogs'. When both cartridges are brought to their minimum length, they are exactly the same length below the 'waist'.
2. You're also right about the bottom O-ring. As a test, I removed it completely and offered up the cartridge to its housing. It went in perfectly - as easy as pie.
3. I then greased the O-ring and replaced it on the unit. When offered up to the housing, it wouldn't go in fully (of course) but I did what you suggested with the three bolts and that worked a treat. I then removed the cartridge, added the rear unit (spring and temp sensor) and put the full assembly back in to the housing. It looked perfect and I was very happy indeed – until I turned the mains water back on and found that the shower just wouldn't turn off. No matter what I did with the flow handle, the water simply continued to pour out at full flow. Do you know why this happened?
4. I removed the cartridge, spring and temp sensor, then put the cartridge alone back into its housing and, when I turned the mains water on, the flow handle worked perfectly. The only problem was the shower would not get warm.
5. I then tried again to install the full assembly (cartridge, spring unit and temp sensor) but, since my first success in getting the whole assembly into the housing, I have not been able to get the cartridge anywhere near the bolt holes with the spring unit and temp sensor installed at the back of the housing. Also, even when offering up just the cartridge (with the O-ring in place) it will now not go all the way in and, even using the three bolts method', I can only get it to within about 1/4 of an inch of being fully flush with the face of the housing - at which point, the bolts will not tighten any more and the cartridge will not move any closer to the face of the housing.
6. As I write these words, I have the cartridge minus bottom O-ring, spring unit and temp sensor, installed in my shower. That allows me to turn the mains water back on and, as a bonus, the showerhead isn't dripping. Sadly, there's no chance of a warm shower unless I get back on the job and somehow make it work. ;(

 

[Phil the Fluter]

CORRECTION: I stated above that, after my initial success following your three bolts method, I am currently unable to seat the cartridge fully with the bottom O-ring fitted. I've just discovered the reason for that is that I didn't have the lower (brass) part of the cartridge fully retracted. I have now fully retracted it and the cartridge has just seated properly and easily with the bottom O-ring fitted. So we have made some progress. ;-)
As I said in my previous post, I was able to get everything installed on ONE occasion (but, while doing that, I'd somehow stopped the shower being able to turn off) but on all subsequent occasions, I couldn't get everything installed because the cartridge wouldn't go in far enough. I'm just wondering whether or not, on those later occasions, I'd somehow expanded the lower (brass) part of the cartridge.
If I try again, with it fully retracted, it might work – but I still don't know why the shower wouldn't turn off.

 

[Phil the Fluter]

UPDATE: with the cartridge adjusted to minimum length, I have now managed to install all the components again but – exactly as happened when I did it this morning – the shower runs at full flow regardless of where the flow handle is set. It won't turn OFF.
As before, I have again now removed the cartridge assembly, set aside the spring mechanism and the temp sensor and re-inserted the cartridge (complete with bottom O-ring). The flow handle now works perfectly but, as before, the water runs cold all the time.
What am I doing wrong?