Slowin' Down

[Carl]

My faithful GMT Master (1979 Root Beer) is losing about a minute each day unless I manually wind it. This has never occurred before, as I have had it serviced regularly over many years. I will admit it is about due for another service; however, I would like to know what I may be looking at with regard to repairs.

[SpaceWanderer]

Only the watchmaker would know for sure. If it's been a good long while since the last service, they'll overhaul it even if it's a fairly minor problem. I'd have my AD send it in and they'll give you an estimate. It won't be cheap (I have a rule of thumb that tends to work most of the time: 10 to 15% the value of the watch) but if it were my '79 I'd definitely go this route so it is good as new. Beautiful watch.

[perpetual92]

Some watchmakers oil the rolex mainspring beyond just putting some tepa on the barrel walls. When the old oil gums up with age it actually starts inhibiting the mainspring. Could be this or grime/grease on the escapement, broken GW pivot or just too much friction combined on dry jewels. I bet its just dirty/dry and needs a fresh mainspring. Are you sending your watch to an RSC or to an independent? I like independents for vintage watches but make sure that person is certified and has a rolex parts account.

When was its last service?

Get it in for a service.

[Carl]

Thanks, Gents!
Just checked my records and it was in for service (to Rolex) in October 2011. Wondering now if it is indeed a mechanical problem vice need cleaning.

[kanikune]

If it happens only when you don't manually wind it, sounds like there is problem in the autowinding system.
After wearing it few days (without manually winding in any occasion) if you leave it on the table, how long will it run?

[Carl]

I have not manually-wound the watch for a few days and will now stop wearing it to see how long the reserve lasts. It has lost -1-minute per day without manual winding. I'll let you know how long it will run off of the reserve.

[gbcecil]

Best guess is lubrication or it got magnetized. I think it would loose more time if it had a broken part.

[SearChart]

Originally Posted by gbcecil

Best guess is lubrication or it got magnetized. I think it would loose more time if it had a broken part.

Definitely not magnitized, it would gain or lose a lot of time in a short period and possibly not run at all. The balance hairspring is very delicate.

I'd say it needs a good clean and new lubrication, probably a new mainspring as well.

[Carl]

'Had to travel so I got a later start than planned on my test. It is now off my wrist and on reserve. I'll keep you posted.
Many thanks for the additional comments!

[Carl]

After being off-wrist and without winding the watch ran for 41 hours on reserve. My layman's opinion is that it simply needs routine servicing; however, I always value the opinions of this forum!

[dom_]

Service needed