What's your thoughts on this Rolex Sea-Dweller, ref. 16600, calibre 3135 project?

[VWatchie]

Yet another Rolex has landed on my bench — this time a Sea-Dweller, ref. 16600, equipped with the trusty calibre 3135, the same calibre as the last one I worked on. The time and date settings are completely dead. I guess the yoke has slipped out of engagement with the sliding pinion. It remains to be investigated. If that is the case, it certainly makes you wonder how it can occur, considering the outstanding quality of these movements. Perhaps it was subjected to trauma? Perhaps a sloppy assembly of the keyless works?

However, it is running very well. A you can see, the maximum delta is seven seconds. The maximum acceptable delta for this movement, as specified by Rolex, is 10 seconds. The average rate fully wound in five positions (crown down, left, up, dial up, and dial down) is 1.8 seconds per day. The rate tolerance as specified by Rolex is -2/+4 s/d. So it's all looking pretty perfect.

What's very strange, though, and something I can't get my head around, is that the first time I measured it on my timing machine, fully wound (I could hear the mainspring slip in small steps while being wound), it performed quite poorly. The rates and beat errors were fine, but the horizontal amplitudes were around 235°, and the vertical amplitudes were all below 200°, which is the minimum amplitude as specified by Rolex after 24h. Performing that poorly, being fully wound, I felt it wasn't much use to measure it again after 24h. However, to be thorough, I nevertheless did and to my astonishment, I got the results as seen in the table above - "Fully wound minus 24h (Not Serviced)" - At that point, I decided to give the watch another full wind and take another measurement, and I got the results as seen in the above table - "Fully wound (Not Serviced)". If anyone has any idea about why I got such a poor performance the first time around, please let me know!

As can be seen, the oil beneath the cap jewel is noticeably depleting. If it wasn't for the faulty date and time setting, I think this amazing watch could have been left alone for another year or two, but considering it has to be repaired, why not service it as well? Especially considering the funny behaviour in amplitude I described in the previous paragraph. What do you think? All opinions are appreciated, but if one of our much-appreciated pros, such as  @Jon, @JohnR725, @nickelsilver, or @nevenbekriev could weigh in, I'm sure it would be appreciated by many.

The fit between the bracelet ends and the lugs was very tight, and I couldn't get the bracelet out by simply pressing the spring bar from one side through the drilled lugs. I'm sure there's an original Rolex tool for it unavailable to enthusiasts, and even so would cost a small fortune.

During the years, I've bought a small fortune worth of tools. Some of those tools have been a complete disappointment and a waste of money, such as the spring bar tool in the picture, which I've never used and have been meaning to resell for a long time. However, as I couldn't get the bracelet out, I came to think of it, and cut myself two pieces of brass rod, deburred and polished the ends, bent them and inserted them in the tool. It worked like a charm. I’ve got to say, I’m kind of proud of this little bit of brilliance. If I’d read something like this when I was just starting, eight or nine years ago, I would’ve been super impressed. Especially considering I could barely tell which end of a screwdriver to use back then. Okay, maybe I’m exaggerating a bit, but you get the gist!

I just hate it when you can't unscrew the case back by using a rubber ball. Is it really necessary to screw the case back on so hard? It's a sincere question. Maybe it is necessary for a true diver's watch like this Sea-Dweller. Fortunately, I had the right size, a number five Rolex die in my set.

Getting the case back off, I had to bring out the "Big Gun". Even so, I had to apply what felt like an insane amount of force. I actually worried the tool might break, and it was not a pleasant experience. So, two thumbs down for the previous repairer, who...

...also decided it was necessary to scratch up the inside of the case back lid, which likely halves its market value. I wouldn't be surprised if the same guy caused the setting problems by being sloppy while assembling the keyless works. We shall see!

I’m really looking forward to hearing your thoughts on my questions and musings!

[Kalanag]

There might be something wrong with the mainspring. I don‘t hear any slipping when I fully wind my 3135.

[VWatchie]

18 minutes ago, Kalanag said:

There might be something wrong with the mainspring. I don‘t hear any slipping when I fully wind my 3135.

That could be another sign it's up for some TLC. Perhaps too much, too little, or the wrong type of grease was applied to the barrel walls. Perhaps it occasionally slips too much, which could explain the funny initial timing machine readings. Thanks for the input!

On second thought, probably not, as it was doing perfectly 24 hours later... Hmm...

Perhaps there is some debris floating inside, getting caught and uncaught between some teeth and pinion leaves!?

If there is one thing I’ve truly learned over the years, it’s that you must be extremely meticulous about cleanliness and observant of different types of debris that can end up in the movement, such as dust, skin flakes, clothing fibers, etc.

Edited yesterday at 03:11 PM by VWatchie

[JohnR725]

6 hours ago, VWatchie said:

Is it really necessary to screw the case back on so hard?

isn't it nice to have a decent case open or when the case doesn't want to be opened? In the case of a Rolex watch that supposed to pass specific water resistant testing you probably do need to tighten the back down. But they shouldn't be tightened so much that they risk stripping the threads out. Then the other problem that comes up is the gaskets can start to disintegrate and then getting the back off can be quite a challenge unless you have a really good tool and perhaps some penetrating oil to loosen things up.

Yes really nice case marking. When I was in school we were taught to mark the cases and  the American watch and clockmakers Institute even had a? So if you joined at one time they would give you an identification number. They were explaining or giving an example of if the watches ever found in you have a unique number they can perhaps figure out the history of the watch or identify the body it's attached to for instance not that that probably comes up that often. So you got a unique number and even made a special metal stamp that you can purchase. It wasn't a super big aggressive stamp but still it left a mark in the back of the case.

Then I heard from people at work on Rolex watches they were using a felt pen indelible but later on they decided that was bad because apparently the ink could release  chemicals although it seems like once it's dry that shouldn't be an issue. Then of course today was nice is you can keep computer records sealed have to mark anything at all I personally find it's best to leave no reference behind that you were even there. Especially when you have a beautiful watch that has no markings at all and now it has your scribbling all over it not good

6 hours ago, VWatchie said:

but considering it has to be repaired, why not service it as well? Especially considering the funny behaviour in amplitude I described in the previous paragraph. What do you think?

typically if there is a typical and watch repair?  a lot of minor repairs you don't need to do a complete servicing. But beyond a certain point you're going to have to take apart a lot of stuff you're going to disrupt the lubrication even if it looks perfect right now and yes you might as well just go ahead the service the whole thing. also in a watch like this where a lot of things seem to be going on the complete service would be better then you'll know exactly where you stand versus dealing with unknown mysteries for prior repair.

[VWatchie]

Thanks @JohnR725! Everything you say makes a lot of sense and is encouraging to read.

[SwissSeiko]

What are your thoughts @VWatchie on adding your service marks to the inside case? I have 2 methods. The first being, if there are already engraved marks from previous services, then ill add mine engraved as well. Kind of tells a story. The other being, if I'm the first one to service it, ill use a fine point sharpie instead, so as not to be the first one to scratch it up. I do like when there are service marks, as it can kind of help me gauge how much I should be examining the movement, before I send my quote out. I found 13 on a vintage Hamilton I service recently, so that's the current high score.

[ColinC]

On 4/27/2025 at 3:35 PM, VWatchie said:

"Fully wound (Not Serviced)". If anyone has any idea about why I got such a poor performance the first time around, please let me know!

How long had it been without any wind before you first put it on the timegrapher?  Perhaps there was some debris / old lubricant that loosened up while you were waiting to do the 24 hour reading?
I recently serviced a Seiko 6319 that immediately after service was absolutely horrible on the timegrapher - 24 hours later (without me doing anything) it was rock solid!  I was a little surprised by this (as I have seen improvements in amplitude after letting it run in but never a watch going from useless to great!).

I was suspicious that some dirt must still be in there so I took it apart and cleaned and lubcricated it again and had exactly the same experience - snow storm that after some hours turned into a nice straigh line with good amplitude 

Edited 2 hours ago by ColinC

[VWatchie]

35 minutes ago, SwissSeiko said:

What are your thoughts @VWatchie on adding your service marks to the inside case? I have 2 methods. The first being, if there are already engraved marks from previous services, then ill add mine engraved as well. Kind of tells a story. The other being, if I'm the first one to service it, ill use a fine point sharpie instead, so as not to be the first one to scratch it up. I do like when there are service marks, as it can kind of help me gauge how much I should be examining the movement, before I send my quote out. I found 13 on a vintage Hamilton I service recently, so that's the current high score.

Well, my fundamental stance is that I want to go in and out without leaving any trace other than a shining, perfectly running movement. So, no scratchings on the inside of the case back lid, no marred screws, no debris, no fingerprints, and so on. That is, my goal is to make it impossible for the FBI to track me down.

As a professional, I suppose you might want to keep track of returning watches, but as @JohnR725 mentioned, we can keep detailed computer records without marking the watch at all. That may not be true for every watch, but luxury and COSC-certified movements do have unique numbers. John also says it’s best to leave no sign you were ever there, and I couldn't agree more.

Now, suppose the Sea-Dweller I'm working on is one day scrapped, and you want to sell the case-back separately (perhaps the case was destroyed in a plane crash). Then the scribbles on the inside no longer reflect the current movement inside the case. Also, the engraving will likely halve the market value of the case back.

59 minutes ago, ColinC said:

How long had it been without any wind before you first put it on the timegrapher?  Perhaps there was some debris / old lubricant that loosened up while you were waiting to do the 24 hour reading?

It had been "sleeping" for about a week and a half.
Yes, the "debris/old lubricant" theory is my hypothesis as well!
It will be interesting to see what I find once I have time to start disassembling the movement.