Omega 2165 Calibre 26.5 Repair & Service

Willy gave me this watch for a repair and service. It is powered by the Omega Calibre 26.5, and was produced during WW2, somewhere between 1939 and 1944 according to its serial number. The watch belongs to his father in law, and will be a present for Willy’s son’s 40th birthday.

The brief was to keep the watch as original as possible, which is like music to my ears. Although this watch could be restored to near new condition, it has aged rather beautifully and it would be a shame to lose its character.

The watch came as a non runner.Omega-2165-service



I start be removing the strap. A lot of oxidation of the springbars here, I think I will fit some new ones!




I open the case. The caseback has the typical perlage finish of Omega watches. Upon inspection of the movement, the cause of the non-running state becomes clear: the balance is sagging slightly with too much end shake, so I am guessing it has a broken pivot.Omega-Calibre-26.5


I decide to address this first, so I source a new balance staff, and upon receipt of the new part I resume the work. I start by removing the balance assembly from the movement.




I strip the balance, removing the hairspring and the roller.





The staff is removed, this is quite a delicate step as it is riveted on the balance wheel.




And here we are, with new and old balance staff. It turns out both pivots were broken.






Clearly this is precision work, the parts are very small indeed.


I now rivet the new balance staff on the wheel using my staking set.Rivetting-balance-staff


I trial fit the new balance into the movement, initially with no roller or hairspring, just to check all is well. The endshake is good, so I can proceed further and complete the balance assembly.






With this out of the way, the service of the watch can commence. Hands and dial are removed.





This exposes the dial side of the movement. More perlage finish here on the plate.


You can see here the parts of the keyless work. They were machined from solid steel, and have a nice brushed finish.




I remove the lower endstone.






And here we are with the dial side completely disassembled.


Moving onto the other side, the balance is already out of the way.


Another very nice finish on the ratchet wheel.



The barrel bridge and train bridge are now off, exposing the train wheels.






I strip the balance cock assembly, so it gets a proper clean with the rest of the parts. The movement is not shock protected, so it is a bit more difficult and time consuming than on a modern movement.



I open the mainspring barrel. You can see this is an old style carbon steel mainspring, the bluish colour was left by heat treatment




The movement is now fully stripped.Calibre-26.5-Disassembled


After ultrasonic clean of the parts, I start by assembling the keyless work.


I then fit a new mainspring. Note the different colour, this is a “modern” alloy mainspring.


I then fit the train wheels and the associated bridge.


And I finish the assembly of the movement. The movement is ticking nicely with a very good amplitude.




I renew the caseback gasket before re-sealing the case.





The watch is now completed, and looking great with a new brown leather strap.Omega-Calibre-26.5-Service


I would like to thank Willy for giving me the opportunity to work on this watch which had great sentimental value to him and his family, it has been a real pleasure to get this watch going again for years to come.








2 Replies to “Omega 2165 Calibre 26.5 Repair & Service”

  1. Hi Olivier,
    Thanks for the amazingly detailed look into my Grandad’s watch repair. It’s so great to see it going again and to be able to use it every day. It’s like I’ve got a little bit of my Grandad back with me.
    Thanks again,
    (Willy’s son)

  2. Hi Alex, thank you very much for your kind words, it was a pleasure.
    All the best

Comments are closed.