Discussion: Repairing a Silva thumb compass

I have a Silva thumb compass that has a hairline crack in the compass housing, hence no fluid. Is it possible to refill the compass housing, and if so, how, and what is the best fluid to use?

Unfortunately I don't have a solution for you, but I do have what-not-to-do.
I had a crack in my Silva thumb compass also and I figured I'd fill it with some alcohol since it has to withstand freezing temperatures sometimes. Well, not thinking it thoroughly, I used the first alcohol I could find. It was this liquid used in to lower the freezing point of the windscreen wiping water. Apparently some part of it (might be propylene glycol) reacted with the compass' plastic and made it all grey (almost opacit). And after that the plastic was really fragile.
If you'll come up with using something other than water, I would suggest to test that liquid onto some other part of the compass and not the housing.

In this old O-Net issue from 1996 someone came to the conclusion that the compass fluid is most like kerosene. Then two years ago we discussed compass bubbles on A/P.

I have tried injecting kerosene into a bubble through a small drilled hole which I then sealed, but found it extremely messy. The fluid seemed to mix with the kerosene however, with no damage to the compass.

OK, I don't know if this is good or bad but you might want to look at this link:
http://www.aircraftspruce.com/catalog/inpages/repa...

What's your plan for sealing up the crack? Personally, I wouldn't bother to try and fix it, but you maybe enjoy this kind of challenge.

I dont know much about fluids, but if rotating bezel of a base plate compass is too stiff, it is not good idea to use insect oil to lubricate it. I tried that once. Bezel rotated nicely for couple of minutes but soon got stuck for good. But the compass has been insect free ever since.

Silva compasses are guarranteed for life. Check the website for details. I have sent broken compassess back in the past, and they were replaced right away.

I had the same problem with a bubble forming. I just drilled a hole in the back. Popped the top and cleaned out all the oil. After gluing the top back on it works just find.

Does the guarantee cover ones that you smash on rocks??

By which, of course, you mean "spontaneously shattered into four pieces under normal usage conditions"? Why yes, it probably would. :)