What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Is it okay for plane to sit for a few weeks?

John, do you own a Mojave Dehydrator? I'd like to hear some pilot reports from those who have used this. I've often marveled that dehydrators were no longer manufactured and I love the look of this one... but is it any good?

I bought one from Jon and it was delivered yesterday. I installed it today. It looks like it will work good. I had to cut about 1/2 “ off my breather tube and it is tight getting the hose plugged into the tube but doable. He sent both size stoppers for my dipstick and I easily changed to the smaller one that fits my engine. I’m not sure how to tell well it is working but it is cycling air through the desiccant so it must be doing something!
 
Dehydration

Rockwood: The included hydrometer, when placed in the desiccant container will indicated the humidity of the air going into your engine. I’ve used inline meters as well that read the same value coming out of the engine after some time.
 
Rockwood: The included hydrometer, when placed in the desiccant container will indicated the humidity of the air going into your engine. I’ve used inline meters as well that read the same value coming out of the engine after some time.

Thanks. I wondered where to put it!
 
Mojave Dehydrator Review

I've used the Mojave Dehydrator for about 2 years on a regular basis. Of course, can't be sure how preventative it is until you take the engine apart. I became a believer when I helped take apart an engine (not mine) that regularly used a homemade dehydrator AND never flew more than a couple hours a month, so it was considered a hangar queen. The engine was amazing clear of any corrosion even though it never flew. The exhaust and intake springs which usually have mild to severe corrosion looked brand new. So, when I got my engine back from overhaul, it was the first purchase I made (Mojave Dehydrator). I like the close system aspect because I plug in after flight, turn on the pump and watch the air temperature in the system rise and watch the humidity in the dehydrator case go from standard 10% up to around 60-80%. In about an hour or two, both temperature and humidity come down back to 10% and ambient temperature. This is my indication that it's working. It takes about 20 seconds to plug in the system and put the timer on for 6 hrs. When it's really humid out, I leave it plugged in constantly. I'm actually going to sell my Mojave system because I just spent the money for the Drybot system! Yes, its 10 times more expensive but I really like the concept behind the system of self-monitoring, self-regenerating and basically a plug and forget. I'll probably put up my Mojave system for $50 dollars so somebody else can put it to great use. More to follow on the Drybot, I finally saved enough of my pennies to afford the thousand + dollar price tag.
 
Let it sit, unless you get it up to operating temp for a while you are doing nothing, definitely not burning off condensation.
 
Holy Batman picture

Ok I posted to this thread before
Well, I have since had a reason to pull my valve covers and found something real curious. Do a borescope and compression test.
To say the least, maybe even scary.
This 650 hour IO-360 cs prop flies at least 4 hours per week. This RV-6A lives in an insulated, sheet rocked and mostly heated hanger. Unless it is flying.
I had just got back from a 3.1 hour flight, 4500' WOT at 2300 rpm.
SDS fuel and ignition and burning Costco premium fuel.
I have a door on the oil cooler and try to keep oil temperature 190+
Tell me this is normal!!!!!!
As I said, WOW IN my engine????
Three covers looked like this and #4 had a bit.
But, what you are seeing is droplets of water under Phillips 20x50 blue bottle oil that has 19 hours on it.
Never expected to see this in the engine for sure.
So can you let an engine sit??? Just look at this picture of an engine that is flown.
My luck is variable Art
 

Attachments

  • valve cover water.jpg
    valve cover water.jpg
    543.1 KB · Views: 121
Purchased a rv6 that not flown in 24 years. Avgas was perfect. I taxied for hours till I could fill with new. Never a miss on engine.
I put avgas in antique motorcycle I have. Starts just about first crank. No gumming
 
As other posters have already stated, I have not seen any data that proves an engine dehydrator prevents corrosion, but agree with others that the theory seems sound and imparts little risk and only a bit of time. I also agree that the dehydrator does nothing for cylinder corrosion.

I just built a "prototype" dehydrator and started using it last week. I cobbled it together using parts procured from Amazon. It a closed loop system that pulls humid air from the oil filler neck and return dry air thru the crankcase breather vent. The orange part is an in-line filter to catch any particulate that the desiccant may create.

thumbnail-IMG-1074.jpg


I hooked it up after a 50 minute flight one evening after work last week. When I first turned the aquarium pump on, the humidity sensor climbed to 90% and moisture visibly condensed on the inside surface of the tygon tubing.

thumbnail-IMG-1088.jpg


After about 15 minutes of operation, the tubing had cleared and the sensor was reading 49%.

thumbnail-IMG-1089.jpg


By the time I left the hanger for the evening, the RH sensor was reading 18%. I have it temporarily hooked to a timer that runs the system 15 minutes a day. I'm looking into building a controller with an Ardiuno and a (better quality) humidity sensor that will try to maintain the crankcase humidity below some (TBD) value.
 
Dean, I have mine hooked to a Swithceon controller. Since we have very poor cell coverage at the hangar it works great for us.
 
I run my dehydrator 24/7/365 and have done so continuously for 3 years (blew one aquarium pump). I have abandoned closed-loop because I don't want to have to lay down on the ground to hook the return line up. No issues, just have to cook the beads a little more often...4 times a year instead of 3. I see no difference in the humidity in the dessicant chamber - closed vs open loop. I typically run humidity in the chamber at around 12-14%, more than enough to shift the dew point out of reach.
 
Last edited:
I run my dehydrator 24/7/365 and have done so continuously for 3 years (blew one aquarium pump). I have abandoned closed-loop because I don't want to have to lay down on the ground to hook the return line up. No issues, just have to cook the beads a little more often...4 times a year instead of 3. I see no difference in the humidity in the dessicant chamber - closed vs open loop. I typically run humidity in the chamber at around 12-14%, more than enough to shift the dew point out of reach.

Thanks! This is helpful data. Do you blow the dry air into the oil filler tube?
 
Back
Top