Low pressure WP testing.

[offshore]

I have just recently finished an overhaul of a vintage SeikoDivers.

Movement service and new crystal, dial, hands, bezel insert, crown,stem, and seals of course.

To WP test it I ran it through a Test 2000 vacuum tester, and then through my Bergeon and tested it to 3 Bar. It came through with no sign of a leak, so I called the owner to collect it.

I was surprised a couple of days later, when the owner showed up with a watch with obvious signs of water ingress inside the crystal.My 1^st thought was that the owner must have left the crown unsealed,however in questioning him, he was adamant that it was tightly sealed.

So I removed the movement, dried and recleaned and oiled it, and tested the case again, paying particular attention to look for the slightest bubble in the Bergeon. I again tested at 3 Bar, and then retested at 6 Bar. (I also retested it in the Test 2000 with a perfect result)

So once again it was reassembled, tested again and returned.

And two days later it was back on my bench with more water inside the crystal!

So now I was absolutely determined to find the source of the leak. The owner had said he had only used it in the pool, so having removed the movement, I resealed the watch, tested it, and placed the case in a laundry tub of water, with only about 9" of water over it, and the bloody thing leaked.

So I dried it, and put it back into the Bergeon, but this time I only pumped 0.5 Bar before immersing it. When I backed the pressure off,I did so very slowly, and detected a minor bubble coming from the crystal side under the bezel at around 2 o'clock. On stripping the crystal out, I noted a black stain in the O ring groove around the 2 o'clock area, so I placed it under the microscope for a better look. This staining was an accumulation of minute dirt particles in an area which looked rougher that the surrounds. After cleaning away the stain, further inspection indeed showed this area to be rougher,and I immediately started thinking of porosity. However I applied some polish to the area, and polished it with a Dremel for a couple of minutes, and the roughness disappeared, and all of the groove area appeared to have the same surface finish.

So once again I lubed the seals and reassembled, and tested in the laundry tub, and then at a number of lower pressures in the Bergeon. And it came through with no signs of water or leaks.

It is now cleaned, reassembled, and back on the wrist of the owner, who has reported back that he has successfully swum in his pool the last couple of mornings.

My take on all this, is that the leak was definetly from this rough area in the crystal O ring groove.

It probably was a build up over the years of something foreign, (maybe even in the grease?) maybe even from new, which marginally corroded the stainless in the groove.

The real learning curve here, was that the results from a Test 2000, and a Bergeon could not be relied on to detect a leak at very low pressure. I assume that when it was tested to 3 Bar the pressure applied, was sufficient to form a seal, and as one then just "backs off" the pressure, and removes the watch from water once the pressure dissipates, there was not enough time for water to enter before it was removed from the tester.

So the lesson learned, is that just because a watch tests as WP at 3 bar or higher, doesn't necessarily mean it can be used for surface swimming, and a "low pressure" test is also needed, to detect any leaks which are otherwise not present under the higher pressure.

Just some more grist for the mill.

Offshore

[FxrAndy]

Thanks OS, some thing to think about.

[kbh]

Very interesting reading. Thanks for sharing.

So my theory of throwing my reps in the deep end of my pool has some merit after all.

[Nanuq]

O/S ... I read about the history of the 1665 and when/why they added the o-ring beneath the crystal retaining ring. It was precisely because of what you found. Over time, corrosion and crud would accumulate between the case and ring, and eventually lead to pitting or a leak.

On my vintages whenever I have the crystal retaining ring off, just before I mount the crystal again I smear a very thin layer of vaseline at the outside surface of the very bottom of the crystal. Then as I press the ring back on it scrapes that layer and pushes it down, forming a grease seal between the ring and case, and between the crystal and case. Plus it helps the ring seat better.

Great writeup!

[AllergyDoc]

Very interesting, thanks for sharing that. Guess I've been lucky: I haven't tested any of the reps I've swam with and none have leaked.