In our 1999 Bavaria 50 Cruiser, both Suunto compasses (model F-116/Sail) started leaking mineral oil at about the same time. After doing some research, I found out that this was not an uncommon problem. Unfortunately no replacement parts were to be found as this is an older model (and also regarded by some as a sealed unit and not repairable).
The general consensus seemed to be to buy new ones. But new units are expensive, and didn’t seem worth the price for how little use they get.
Luckily, using my 3D printer I were able to produce tools to make it easier to disassemble it, as well as designing a replacement for the broken bellow. Since disassembling the original unit requires a vise and special tools, I designed new parts to make it easier to reassemble with only a screwdriver. I also made a small holder for a red LED-light, as ours only had an old light bulb glued on.
Getting the old compass apart is best done by dipping the lower “cup” in boiling water for about 30 seconds to soften the plastic, and then placing it in a wise with the 3d printed tools. This way the cup is squeezed off the compass body, and will pop of rather easily when enough pressure is applied.
After getting it apart, clean all parts before starting to assemble again. I rinsed them in water, and cleaned them up with lint-free cloth. To not touch the compass dial though, this is very delicate and can easily bend. Any white spots or discoloration on this that shows up when it dries are invisible when the compass is refilled, so don’t worry about them.
Then its time to reassemble. Putting the new bellow on, ensuring that it fits well, the newly printed part to ensure a tight fit is put on and tightened with a screwdriver, using A4 stainless screws which are not ferromagnetic.
For replacing the old mineral oil, fragrance-free baby oil were used. A syringe were needed to get the oil through the small refill-hole. Filling the compass and refilling the syringe takes time and patience, so one can save some time by filling the compass nearly full before putting on the clear acrylic dome. Then the rest of the oil is filled through the fill-port, tilting the compass so one can get the last bubble of air out before replacing the seal.
Turn it around some times to make sure there aren’t any small bubbles stuck under the dial or elsewhere. My experience is that very tiny bubbles will dissolve after a day or so in the mineral oil.
So both compasses are now good as new. Hope this can help other who have given up hope on these compasses.
Due to there being some demand for these, the drawings are available at thingiverse. Since printing these are rather difficult due to the very flexible filament (and not everyone has access to a 3D printer) you can now buy the complete kit from me