Restoration Workbench Seiko Liner 14090 – How Resistant to Water were Seiko’s Earliest Waterproof Watches?

Seiko will claim that waterproof watch production started in earnest in 1965 with the 150M 62MAS, however in the years prior to the 62MAS, Seiko did experiment with water proofing other models. Many collectors will agree that Seiko’s first waterproof watch was the manually-wound Seiko Cronos ‘Sea horse’ from the Daini factory, released in December of 1959, but the 1960 Seiko Liner from the Suwa factory was not far behind

Our example is from 1961 and shares the same seahorse motif on the caseback as the Cronos. The seahorse was used on the back of waterproof manually-wound watches while the more familiar dolphin casebacks were used on the automatic watches, such as the waterproof Seikomatic. 

The seahorse motif indicates a waterproof, manually-wound Seiko

The waterproof Liner proudly proclaims its 30m rating on the dial, and while that does not sound like much today, it was a quantum leap for a company producing dress watches without rubber seals up until that point. That 30 meters of water resistance was achieved through the use of a pressure fit bezel sandwiching a robust crystal with a lip on the case and seals on both the crown and the caseback (which, however, still only snapped on). No screw-down back or screw-down crowns just yet – they would become common place as the 1960s progressed

Our example was sourced from a Japanese auction site as an addition to my early sixties Seiko collection. These are quite rare so allowances were made for the condition of the watch, which was not the best. I won the auction, paying more than I wanted but less than I was prepared to. While assessing the condition of the watch from the photos I missed one thing. You might notice it in the photo below, reproduced from the auction listing.

Original Auction Ad
A photograph from the original auction

Do you see it? Look closely at the bezel… it is cracked at 7 o’clock. Well, I didn’t notice that until he watch arrived in the US some days later. Typically, a cracked bezel complicates these restorations since, firstly, a replacement has to be found and they can be very hard to find. It’s not like anyone is making new case parts for these watches anymore. Secondly there is the concern that the crack is indicative of further damage within the watch.

Cracked Seiko Liner Bezel
Close up of the cracked bezel

Cracked bezels are not unusual on certain vintage models. For example, the 45KS King Seiko bezels are often found cracked. My guess is that the bezel to crystal tolerance on the 45KS is too tight for the thickness of the bezel and so eventually it succumbs to tension, perhaps exacerbated by steel that was not quite strong enough.

The cause for this Liner’s bezel failure seems to be different and has its roots in that water proof rating. Popping off the bezel, now easy with the crack, reveals a large amount of rust underneath. Did the rust cause expansion under the bezel cracking it, or did the cracked bezel allow water in to start rust? It’s a good question without a definitive answer, but I’m tempted to think this was a waterproof watch that was used underwater and the water ingress came first, causing rust expansion, which cracked the bezel.

Evidence of water ingress below the bezel
The extent of the rust underneath the bezel

As everyone knows, water ingress can be deadly for a vintage watch and so the sight of this much rust put me on edge a little. With so much rust in and around the case I was not expecting the dial or movement to have escaped moisture-free. I should have had faith in those Seiko engineers designing their first waterproof cases though. With the crystal removed, it was clear no water had breached the small steel wall on the inside of the crystal. Even with the cracked bezel, the crystal fit had been tight enough to repel the oxidized hydrogen invader.

Once the small particles of rust from the case were blown away, the dial proved to be almost perfect. I had been concerned looking at the original auction photos that the dial had yellowed which would clash with the monochrome and blue color scheme of the watch. With the crystal removed it was clear that the yellowing seen was the old the crystal not the discolored dial. With new glass, the silver-grey sunburst finish with its dab of blue will look as good as new.

Opening the caseback seemed to suggest that the waterproof case design had done its job here as well. The caseback seal was still a little pliable which is unusual for a watch this old. Clearly, the seal had stopped the water that had seeped under the caseback. The movement within its large steel movement ring looked clean, dry and shiny.

No sign of water ingress past the caseback seal (removed in this photo)

Two of the three waterproof features of the watch had done their job successfully. The tight crystal secured with the bezel had kept the water from the dial. The rubber caseback seal had kept the water out as well, but what of the third feature, the crown seal? Unlike every other Seiko Liner watch, the 14090 has a waterproof crown of Seiko’s regular 60s design, albeit without the typical SW signing. As we can see, the lack of rust on the crown tube shows that the seal was successful and had stopped any water from getting inside the movement past the crown.

Early Seiko waterproof crown
No water made it past the seal of the early waterproof crown

The 3140 movement is high quality but also very straightforward and so the strip down for service proceeds quickly. There was a large amount of oil on the barrel bridge under the ratchet wheel. I’m not sure why. There were no service marks inside the case back, but it looks like someone filled the barrel with machine oil rather than giving the watch a proper service. 

Seiko 3140 movement
The 3140 movement had been perfectly protected from the harsh environment

Disassembly proceeded quickly and uneventfully until removal of the center (second) wheel and corresponding cannon pinion. The center wheel had a tell-tale glint of purple on its arbor indicated a broken center jewel. Sure enough, the jewel that acts as the bearing to the center wheel (turning once per hour) as it passes through the main plate and attaches to the cannon pinion had cracked.

Fragments of the Seiko Liner center jewel
Fragments of the center wheel jewel
Remains of the Seiko Liner center jewel
Damaged center wheel jewel

The cracked jewel was removed and a replacement fitted before the movement was run though the cleaning cycle. 

Fitting the replacement jewel
Inserting the replacement center jewel

With the movement in the cleaner, it was time to turn my attention back to that rusty case. The plan was to remove the rust, treat the case to stop it returning and hope that the final pitting would not be so bad as to render the case unusable. 

Removing the rust around around the crystal revealed a surprise. Under the rust was the remains of a crystal gasket. This was another feature Seiko had added to this waterproof case. Few Seiko watches of this time period had crystal gaskets, most were just press-fit into metal bezels under compression. What the gasket had been been made from was unknowable from its state now. It seemed to have petrified to the point where I had to chip it away in chucks using an old screwdriver. 

The pitting of the case turned out to be pretty minimal. I won’t be wearing the watch in the water but I would not be surprised if the restored watch would still be able reach it’s 30m rating once it was cleaned up. A new bezel (p/n 8333-956) and crystal (p/n 338W01AN) were sourced and fitted to the cleaned up case along with new seals.

Seiko Liner 14090 case, crystal and bezel
New old old stock crystal and bezel fitted

With the case complete, it was time to turn back to the movement. Reassembly does not take very long with these 3140 movements. The tolerances are a little tighter than a standard Seiko Marvel but this only impacts reassembling the hands. The clearances there are minimal, so care needs to be taken. In particular, if the dial is not sitting close enough to the main plate, there will not be enough room for the hands.

Refitting hands to Seiko Liner
Refitting the hands to the movement after service

And after fitting the movement back into the renewed case, it’s finished. My finding a new old stock (NOS) bezel after I had not realized the original was cracked was certainly fortunate. It enabled a full restoration on this early attempt at a basic waterproofing.

completed restoration
The completed restoration

This early water resistant watch clearly spent time in a wet environment, but the movement had been kept demonstrably safe and dry. Ultimately the water damage was superficial and easily fixed, allowing this watch to be useful again, protected from the elements despite its rudimentary 1960s protections.