Homemade engine dehumidifier.

[Will.iam]

11 minutes ago, DonMuncy said:

My understanding is that a Black Max sells for about $600; meaning yours was about $300. That is a very good price for an engine dehumidifier. Mine was not that expensive, but you didn't have to buy parts and assemble yours; and you don't have to cook the pellets every 4 months or so, like I do. Thanks for the information.

Link is posted above $295 on amazon plus the dehumidifier power switch if you want to control the range. If you have an enclosed space the dehumidifier has it’s own humidity setting. Problem for me was that sensor was not in the engine and my hanger is not sealed enough to do the whole hanger space so I improvised with the power switch. 

[Will.iam]

Just now, Will.iam said:

Link is posted above $295 on amazon plus the dehumidifier power switch if you want to control the range. If you have an enclosed space the dehumidifier has it’s own humidity setting. Problem for me was that sensor was not in the engine and my hanger is not sealed enough to do the whole hanger space so I improvised with the power switch. 

P. S. My wife liked my airplane one so much she took it to keep the house at a lower humidity especially in the spring and fall when the temperature is fine but there is too much humidity in the air so i got a second one for the airplane. If she had her choice we would live in the desert i think. 

[Pinecone]

The AC based units will get the dew point down to about 36 - 40 degrees.  So in the winter, in an unheated hangar, they don't do much.  They do slightly warm that air through the process, so the RH is a bit lower.

The Black Max actually runs below freezing, and cycles to melt the ice.  So the dew point is somewhere below 32 degrees.

One thing I like about the Black Max over repurposed AC based units is, it delivers a more reasonable amount of dehumidified air just through the engine.

The silica based ones need some attention, so not optimal if you are out of town for longer periods.

[Fly Boomer]

8 hours ago, Will.iam said:

There are days where the outside humidity is less that my set level and the dehumidifier never comes on, by the rainy days it almost never shuts off for long

Where do you put the detector for the humidistat that controls power to the dehumidifier?

[Fly Boomer]

20 minutes ago, Pinecone said:

The Black Max actually runs below freezing, and cycles to melt the ice.  So the dew point is somewhere below 32 degrees.

I read through the Black Max info, but didn't find it satisfying.  I understand that the pressure side goes into the crankcase vent, and that it pushes air through open valves into the intake or exhaust system, but what if both valves are closed?  Also curious if you take the dipstick out or oil filler cap off to allow air to escape directly from the crankcase?

[Pinecone]

There is no way for the air to get from the crankcase to go through the valves.

None of the systems mentioned deal with dehumidifying the cylinders.  To so that, you would need to blow air into both the exhaust and intake, and you would still miss one or two cylinders.  And there would be flow in only one or two since blowing air into a cylinder with one valve closed, does not work well.

With the Black Max, you would need to pull the dipstick out a bit or open the oil filler so that air can flow.

[Fly Boomer]

10 minutes ago, Pinecone said:

There is no way for the air to get from the crankcase to go through the valves.

None of the systems mentioned deal with dehumidifying the cylinders.  To so that, you would need to blow air into both the exhaust and intake, and you would still miss one or two cylinders.  And there would be flow in only one or two since blowing air into a cylinder with one valve closed, does not work well.

With the Black Max, you would need to pull the dipstick out a bit or open the oil filler so that air can flow.

Paragraph two of the "installation manual" (2065 Installation Manual.pdf) which I downloaded from their web says:

"The Black Max is an electrically powered device that produces a continuous supply of low humidity air.  This air then flows into the engine crankcase through a special adaptor which is inserted into the end of the breather tube, and exits the engine through the intake or exhaust system." [emphasis mine]

Is the 2065 a different model?

 

[Will.iam]

20 minutes ago, Fly Boomer said:

Where do you put the detector for the humidistat that controls power to the dehumidifier?

Right in the top of the oil filler tube. I did try at the breather vent but once the dehumidifier stoped at the correct level it wouldn’t start up again. By putting the sensor at the top. Heat rises and with it the humid warm air so it cycled more with the sensor at the input than the output. Plus less soaking the sensor with oilly air.  

[DonMuncy]

2 hours ago, Fly Boomer said:

  Also curious if you take the dipstick out or oil filler cap off to allow air to escape directly from the crankcase?

I built a one-way air escape valve to fit over the oil filler neck on my K model.

[Pinecone]

1 hour ago, Fly Boomer said:

Paragraph two of the "installation manual" (2065 Installation Manual.pdf) which I downloaded from their web says:

"The Black Max is an electrically powered device that produces a continuous supply of low humidity air.  This air then flows into the engine crankcase through a special adaptor which is inserted into the end of the breather tube, and exits the engine through the intake or exhaust system." [emphasis mine]

Is the 2065 a different model?

 

Hmm.  So they are relying on the leakage past the rings.

That would help the cylinders, but I question how much air they are actually flowing through the engine at all then.

[redbaron1982]

I was wondering if there could be any issue from having too low humidity in the engine compartment? I mean, can silicone, plastics, seals get cracked due to too low humidity?

[Fly Boomer]

16 minutes ago, Pinecone said:

Hmm.  So they are relying on the leakage past the rings.

That would help the cylinders, but I question how much air they are actually flowing through the engine at all then.

Not sure.  It seems that if the pressure was high enough to force air past the rings, if there was a low resistance way to get out, like the filler neck, all the air would go that way.  Maybe they plan for all the pressure to escape through the rings, which would eventually scavenge the moisture in the crankcase on the way out?

[Will.iam]

44 minutes ago, redbaron1982 said:

I was wondering if there could be any issue from having too low humidity in the engine compartment? I mean, can silicone, plastics, seals get cracked due to too low humidity?

Better remove all those airplanes from the boneyards in the desert then.   if it was an issue isn’t as important as saving the metal from corrosion. 

[redbaron1982]

10 minutes ago, Will.iam said:

Better remove all those airplanes from the boneyards in the desert then.   if it was an issue isn’t as important as saving the metal from corrosion. 

Good point, lol. 

[neilpilot]

4 hours ago, Pinecone said:

The AC based units will get the dew point down to about 36 - 40 degrees.  So in the winter, in an unheated hangar, they don't do much.  They do slightly warm that air through the process, so the RH is a bit lower.

The Black Max actually runs below freezing, and cycles to melt the ice.  So the dew point is somewhere below 32 degrees.

One thing I like about the Black Max over repurposed AC based units is, it delivers a more reasonable amount of dehumidified air just through the engine.

The silica based ones need some attention, so not optimal if you are out of town for longer periods.

If you use a sufficiently large quantity of silica, you can get surprisingly long service life between changes.  I used a home-build silica dryer with a large silica reservoir, powered by an aquarium air pump.  When I returned home after 2 months in storage in my hangar, the silica reservoir indicated only about one third depletion.  That was in Memphis in May & June, not the most humid time of year but this is Memphis so definitely not dry.

[Pinecone]

2 hours ago, redbaron1982 said:

I was wondering if there could be any issue from having too low humidity in the engine compartment? I mean, can silicone, plastics, seals get cracked due to too low humidity?

There can be issues with some things, but considering the heat in the engine compartment, most things have been baked dry many times.

[Pinecone]

2 hours ago, Fly Boomer said:

Not sure.  It seems that if the pressure was high enough to force air past the rings, if there was a low resistance way to get out, like the filler neck, all the air would go that way.  Maybe they plan for all the pressure to escape through the rings, which would eventually scavenge the moisture in the crankcase on the way out?

I would have to read the directions again, but do the recommend lose oil dipstick/oil filler or not?   If so, the air will not go past the rings.

And not sure what other pathways there are out of the crankcase.  But if the only flow is what gets past the rings, then it will take a good amount of time before the water is removed from the crankcase and from the oil.

[Pinecone]

26 minutes ago, neilpilot said:

If you use a sufficiently large quantity of silica, you can get surprisingly long service life between changes.  I used a home-build silica dryer with a large silica reservoir, powered by an aquarium air pump.  When I returned home after 2 months in storage in my hangar, the silica reservoir indicated only about one third depletion.  That was in Memphis in May & June, not the most humid time of year but this is Memphis so definitely not dry.

That would also depend on where you are and what the humidity has done over that time.   Silica gel will last a VERY long time in AZ, but not long in FL. 

[neilpilot]

2 hours ago, Pinecone said:

That would also depend on where you are and what the humidity has done over that time.   Silica gel will last a VERY long time in AZ, but not long in FL. 

Obviously, but the point I tried to make in my post is that the service time can be greatly extended by increasing the size (weight) of the gel pack.  I used a large quantity of gel to ensure it would remain effective.  The gel is typically effective until it contains about 40% water, and it can also easily be regenerated many times.

[DonMuncy]

3 hours ago, neilpilot said:

  The gel is typically effective until it contains about 40% water, and it can also easily be regenerated many times.

I have been using the same dehumidifier medium for 10 years, or more likely a lot more than that.

[201Steve]

I would like to see some examples of dehumidification in the airframe. Wings, underbelly, etc. Anybody heard of this?

[M Terry]

I made a device for this purpose out of a 12v aquarium bubbler ( i think it was meant for use in bait wells of fishing boats) and a plastic jug full of desiccant. The motor draws air from the engine vent tube and pushes into the bottom of the jug. It flows through the desiccant granules and out a hose which goes into the oil dipstick hole. Runs off some old BB600 nicad aircraft batteries that are charged by a small panel on the roof of the hangar.Runs intermittently controlled by a timer.

You need to seal the case of the pump and then drill a hole in it to get it to draw from the hose.

the granules change color after a few weeks in use. put them in the crock pot for a few hours and they are ready to be put back in the jug.

A humidity meter on the outside and one inside the jug demonstrates the difference in humidity.

I used left over suction tubing from the hospital, hot glue and duct tape.

Edited December 22, 2022 by M Terry
more details

[N201MKTurbo]

You could do it like the dry boxes at Intel. They just have a humidistat that controls a small solenoid valve that admits house nitrogen. It keeps them at about 0.5%RH It doesn't use much nitrogen.

I like @M Terrys, It looks like the right solution. I would probably put a humidity sensor on to save battery life.

I would like to see a picture of @DonMuncys dehumidifier.

[N201MKTurbo]

Or you could move to Arizona where we need humidifiers to keep the seals from drying out.

[RoundTwo]

I like these ideas and it sounds like it will work well to protect the cam and lifters that are exposed to crankcase air, but what about cylinder bores? Are there any ideas on how to keep the jugs rust free?