Thermostat repair

Discussion in 'Mech Tech' started by Barry Haynes, Jun 12, 2020.

  1. As I was doing another one I thought I would do a how to this is the same procedure for any air-cooled thermostat

    (1) with a small hobby torch heat up the end of the thermostat that has the thread on and the end will come off, take a cotton cloth and while it is still warm wipe off the solder and clean the surfaces
    (2) the threaded bit is hollow heat this up and remove the solder
    (3) next take some flux paste and apply to both surfaces now clamp the thermostat in a vice and heat
    (4)now you need to take a syringe and add 2 ml of 99% isopropyl alcohol through the threaded tube
    (5) with the thermostat still in the vice carefully heat the threaded piece and seal with solder
    (6) job done test to see it it opens on the stove

    A type 4 thermostat opens at 85° and isopropyl alcohol opens at 82 ish so close, I've now done 3 and none have failed


    Sent from my Pixel 3 XL using Tapatalk
    iblaze, Coda, Surfari and 15 others like this.
  2. Think you need to get the Brasso out now Baz for the final topping .
  3. Where did the original alcohol go?
  4. What!!!

    I've just bought a new one from the US and I'm embarrassed to say how much it cost in total.

    If I send you my old one can you fix it for me to have as a spare?
  5. If I can do it you professionals will yellow snow it:thumbsup:
    Betty the Bay likes this.
  6. Good question.
  7. when they fail there is a hole somewhere so there, and also when you heat it up it will burn off, of the 3 I've done all were dry inside
    paradox likes this.
  8. Filled with London Pride .
    CollyP and Barry Haynes like this.
  9. Baz drunk it.
    Barry Haynes likes this.
  10. Found it, here is what I followed
    Mark Darby and paradox like this.
  11. Like it like it Rodney
    Faust likes this.
  12. Gingerbus, snotty and CollyP like this.
  13. I just had a re think this only applies to T4 thermostats because the isopropyl alcohol has a boiling point of 82, for a T 1 you will have to search the net for the correct alcohol
    JamesLey likes this.
  14. I love it when the unfixable becomes fixable. Gives me one less thing to worry about. Great skills btw.
    snotty likes this.
  15. Why thank you,
    The only problem I can see is when the bellows are damaged but Ratwell say that the majority of leaks are where they are soldered
    paradox likes this.
  16. You did that “How to do a white-eared elephant”, but that got deleted.
  17. Nicely done. I managed to fix mine after many attempts but I did not seem to have the hole in the side thread or I missed it! I filled from the end of the threaded bolt and that caused me my issues with the alcohol stopping the solder fixing.
    mcswiggs and Barry Haynes like this.
  18. There is a hole at the side at the bottom of the thread fill this first which should stop the alcohol them fill the top with solder, well done by the way:thumbsup:
    Chrisd likes this.
  19. I always presumed they failed because they had split and thought soldering them up wouldn’t last
    I didn’t realise most failed because the solder failed
  20. I've read many articles on this what is said time after time that the solder is the weakest part and most fail there
    Valveandy, paradox and JamesLey like this.

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