Remove old screw down crown seal

[familyguy]

I have a dive watch I purchased new, in the early 1970's with ETA auto wind movement, It's looking a bit sad and I would like to get serviced and looking nice again, it is I hope a good candidate as it was only ever serviced by a watchmaker, recently I tried to unscrew the crown, it was very stiff, when it came undone I noticed a black goo around the crown tube, looks as if the seal/o-ring has disintegrated, my question is how to get the goo out of the crown thread, is there a solvent I can soak it in. I did once have a winchester of benzene but was forced to get rid of it on pain of divorce - I'm sure benzene would have done it.

Edited December 12, 2020 by familyguy
Correct a typo

[oldhippy]

Its best to replace the crown with a new one if the old one is in that condition. 

[watchweasol]

Hi Ditto  old Hippy, having got a new crown then experiment removing the old goo the experience will come in handy for the future,   IPA, Ronsonol, benzine will probably do the trick, finding the correct cleaner will be handy as case back gaskets also get in this state.

[rodabod]

Do you have a photo of the crown? I think it could be quite tricky to fit a new gasket. 

[familyguy]

Here are pics of the offending parts, movement is an ETA 2783, this is the first time I have removed the stem/crown and I notice that the square section of the stem has a twist in it - is this normal ? I'm assuming it is, as the watch was only ever serviced by a watchmaker and I doubt the stem could transmit enough force to twist the square section, I feel the the stem would break at the thread - the thinnest part.

[rodabod]

I reckon you may be able to get a matching replacement from cousins if you are based in Europe. 

[watchweasol]

Somewhere in the recesses of my mind  I seem to recall that the stem is correct with the twist but will have to dig deeper. 

[jdm]

On 12/12/2020 at 4:39 AM, familyguy said:

I did once have a winchester of benzene but was forced to get rid of it on pain of divorce - I'm sure benzene would have done it.

I think you may have had benzine (motor petrol, gasoline) not benzene, the confusion is common among English speakers. Anyway the cleaning agent is not important because to replace the gasket in the crown you have to lift the top washer anyway, as said that's a bit of fiddly work but certainly doable. Or fit a new crown.

 

11 hours ago, familyguy said:

I notice that the square section of the stem has a twist in it - is this normal?

Yes it is, for period of time ETA was making movements with a twisted stem, probably with the idea these would help the clutch wheel pressing, then fortunately they stopped.

 

11 hours ago, rodabod said:

I reckon you may be able to get a matching replacement from cousins if you are based in Europe. 

Even if you're not, Cousins UK ships worldwide for the actual Royal Mail cost.

[oldhippy]

32 minutes ago, watchweasol said:

Somewhere in the recesses of my mind  I seem to recall that the stem is correct with the twist but will have to dig deeper. 

That stem is correct it is to help it to engage. 

[watchweasol]

Good to know the brain still works occaisionally    thanks Old Hippy

[Nucejoe]

Correct stem.

Soak in diesel fuel or boil the stem/crown in boiling water for 10 min.

The seal was originally molded by heat, 250-400 degree C  steam.