My engine has been out of the sealed bag for several months now, and with the hot summer days I'm seeing some pretty high humidity in the shop. Since I had to drain the preservative oil out of at least part of the heads when I installed the exhaust and since I've also got quite a bit of travel this fall, I'm not going to have the first engine start as soon as I'd hoped.

Therefore, I thought it might be a good idea to get some kind of control over how much humidity is inside ether engine. I wish I could take credit for this contraption, but the reality is that I shamelessly ripped off this idea from somebody on VAF.

I threw this together prior to going with Holly on her house hunting trip, but the humidity sensor wasn't delivered by amazon until after I was already gone on that trip so I didn't have any way to measure what it was actually doing. Once I got back I reworked it to it's current configuration.

I logged 12 hours for this job because of the research and time it took to shop for the parts. But once I had a plan together, it really only took about an hour to assemble "the device". For those who are interested, here's a more or less complete parts list. Almost everything came from Amazon with the exception of a couple of scotch bright pads I already had in the shop and the clean containers, which are just food canisters from the dollar store.

4 lb jug of desiccant (I used about 1/2) $25.99
3/16" brass hose barbs (5) $15.99
Aquarium pump $4.48
Aquarium hose.filter/union kit $6.99
food canisters (dollar store) $12.00 (approx)
Digital thermometer/hydrometer $10.97
Rubber plug from the ace hardware $3.00 (approx)

3d printed oil filler cap from somebody on VAF who did a proof run and was giving them away.

I also installed dehydrator plugs at the same time, but I don't thing that you would really need to as long as youre running "the device". It's more of a belt and suspenders approach.

I'll pretty this up at some point for hangar use, but just to explain what you're looking at here; all components are just duct taped to a piece of pink foam that I had laying around.

The aquarium pump usually just pulls ambient air in through a hole in the case. I covered that hole with shoe goo sealant and installed a barbed fitting through the case so that it would have to suck air through that barb.

The lower canister is plumbed with a hose barb near the bottom to an aquarium air stone, then a couple of layers of scotch bright pads that I has laying around, then a layer of desiccant, then another layer of scotch bright, then another air stone to a hose barb near the top. The only thing the scotch bright does is keep the desiccant beads from sloshing around in there.
the upper canister is just plumbed with two hose barbs on opposite sides for a simple in/out arrangement.

So what happens is that a rubber plug is center drilled and plumbed with an aquarium hose. This plug goes in the oil breather tube. Crankcase air is sucked from the breather through the gauge chamber, into the pump, out through the desiccant chamber then back into the engine through a barbed fitting in the cap on the dipstick hole.

Once the switch was flipped, humidity went from 47% down to 10% as measured on a $10 temp/humidity gauge that is just laying in the top chamber. Elapsed time was just a few minutes.

I originally got fancy and had this on a timer so that it was only running for a few hours a couple f times a day, but in between running sessions the gauge was creeping up to about 15%-20% humidity, so I ditched the timer and just have it on 24/7 at this point.

I'm guessing that the fluctuation is likely because of air leaks around the lids on the el' cheapo dollar store food canisters, but anyway, aquarium pumps are designed to run all the time anyway, so all good for now.

This was a fun little side project and I'm really happy with how it turned out.