My steam altimeter knob is very hard to turn

[Doug Rohrer]

I parked my RV-9A outside for a week and someone removed my pitot tube cover. Water got in the pitit system during a rainstorm. Soon after, my altimeter started getting hard to set and no longer accurately tracked altitude. I am looking at it as I type: it is now a paperweight.

[N8RV]

I had water vapor in mine last year and the knob was getting hard to turn, too. Out of nowhere the instrument face was fogged. I started looking for a new one.

Given that I never look at it anyway (my Dynon EFIS is my primary) and that it was going to be a paperweight, I figured I had nothing to lose if I took it apart. So I did.

I took off the front cover, set the unit on the bench in front of a portable heater to dry it out. After an hour or so, I put it back together. The knob turned much more easily, and there was no fog, so I put it back into the panel.

That was over a year ago and it works just dandy. In fact, it was always about 100' off the EFIS altitude with the same baro setting, and now it's within 20'. Go figure. And the knob works just fine, too.

Hey, if you have nothing to lose, try taking it apart and drying it out. Might save you a few hundred.