Jeff Vaughan
Well Known Member
Has anyone built an engine dehydrator? Are there plans available?
When the silica turns blue, place silica in oven and heat at 350*F until it turns pink again.
Backwards.
Every time you put the plane away after flight, open the oil filler cap, then put a wet/dry vacuum on the crankcase vent while the engine is still hot.
Or modify an old hairdryer to disable the heating elements, put a reducing cone on the output end, and run it on a low setting for a few minutes through the oil fill/dipstick tube to blow the worst of the vapors out the 'case vent.....Every time you put the plane away after flight, open the oil filler cap, then put a wet/dry vacuum on the crankcase vent while the engine is still hot. The vacuum will suck out vapors before the crud condenses on the metal. The air you suck in thru the oil filler cap contains less moisture and none of the corrosive byproducts of combustion. Only takes a couple minutes.
I finished mine last month for under $40 which included a new plastic Stanley 16" tool box from WalMart. Mine is a closed loop system drawing through the breather vent tube, into the tool box holding the silica bottle at one end and sucked out through the other end via the aquarium pump with a stone filter buried in the silica. The dry air then is pumped into the oil filler tube sealed with a rubber stopper. I like Rivetheads use of an old filler cap to screw on and will modify mine to do the same. My stopper worked loose one time. Its a nice portable system with everthing self contained in the tool box.
I built one of these this winter for the Skipper - I get the satisfying plume of moisture everytime I turn it on. The first 1/2 inch or so of the HF pellets have turned pink. I'm glad that moisture isn't in my engine any more!
ok, i have read all the posts on this and unless i am missing something i can't see how this can be reducing moisture in the air it pumps by more than a miniscule amount. the pump is pulling air from the hangar and into the engine? if the pump was pumping a closed circuit from engine back to engine maybe but this pump is probably taking at least a couple cubic foot of air a minute. i don't in a million years believe that a quart of silica can be pulling the moisture out of a volume of air like that for very long. i imagine the calculations could be done to figure the water in a cubic foot of air at stp and a given humidity and i am not going there but i bet the air humidity change in and out with the air pump can't be measured. also, the air is being sent all around the parts that are constantly splashed with oil. no way for the air to get the upper cylinders etc.
my thoughts on keeping rust away are always shut down the engine after getting it hot, remove dipstick cap and keep all the engine metal warmer than the surrounding air.
and i could be all wrong.
I have three humidity meters that I threw into the dessicant chamber. The ambient humidity at my hangar today was 74%. The humidity in the chamber containing the air that is being pumped into my engine is 12%. I conclude that the air is being pumped into my engine is substantially drier than the air that would be there if there was no dehydrator. I could be wrong.
edit: I don't do a closed circuit like Wirejock. I did, but it was too much of a pain to get down there and plug it into my oil separator after each fligh, so I just go open circuit. Probably have to cook the dessicant more than he does, but I think the humidity of the air going in is what matters.
One strategy is to use a pool toy inflator or similar to blow a higher volume of ambient air through the crankcase for several minutes after returning to the hangar, evacuating any post-shutdown moisture-laden air, thereby less crankcase moisture to condense as the engine cools back toward the dew point. I don't do that routinely, but I do have a 12-inflator in the hangar somewhere. I mostly just plug in the dehydrator as soon as I get it in the hangar.
Has anyone built an engine dehydrator? Are there plans available?
This is a closed circuit design so the beads don't saturate very quick. I've been using this for over 2 years and only dried the beads once.