Engine Dehydrator

[Alan Maurer]

Mooney People

Anyone use a Black Max engine dehydrator? I saw one used on a Bonanza. and the tube is put in the engine breather. Since I live in humid Florida, it seems like a good idea. 

And  where is the Ovation engine breather found?  Any thoughts?

Thanks

Alan

[A64Pilot]

I don’t think it would hurt, but if you’re a DIY type it’s about one of the easiest thing to make yourself there is. Just need something air tight to hold dessicant bags and a tiny aquarium air pump, tiny one as you barely need any air at all. Oh, be sure to close off the breathers “whistle slot” when your using the drier

Good dessicant  bags have instructions on them on how to reactivate them in your kitchen oven overnight.

Everything in the Army came in cans with dessicant bags, engines, transmissions etc. I kept a bunch, but have lost them over the years, I should have kept a lot more.

The mil spec dessicant bags maybe are three lbs or so and have the recharge instructions on them

The breather is the tube near the nosewheel that drips oil. My J models is at the back of the left cowl flap, but the oil drip is your clue

[slowflyin]

I've been using one for many years.  Works great!   When I first got it I tested with humidity levels and remember excellent results.  Sorry, I can't offer the exact data as it was a long time ago.  Of note, my unit has malfunctioned twice over the last decade or so.  Both times I received excellent service!   Both failures were in the early years.  It's been at least six or seven years since the last repair and its running strong.    I highly recommend both the product and the vendor.  

[Pinecone]

The Black Max does not use desicant, so you don't have to keep checking and regenerating the desiccant. 

There is one I saw recently that uses desicant, but self-regenerates.

Here it is - DryBot Automated Engine Dehydrator (rpxtech.com)

 

[GeeBee]

I made my own unit with desiccant, but the BlackMax unit is appealing to me. I am glad to hear good results.

As to the Ovation breather pipe location, left side next to left exhaust pipe.

 

[Will.iam]

I went a home grown route with a whole room dehumidifier and just pipe the output down through the oil filler tube with a humidity sensor that is controlled my the power plug. This way it’s a controlled loop and my humidifier only runs when the humidity inside the oil fill tube gets above my set point of 45% and then turns off at 29%. This keeps the on off cycles at least 15 mins apart especially when it’s raining outside the hanger and the humidity outside is high. What is amazing to me is when i first put it on right after engine shutdown just how much steam comes out in the first 5 minutes. I think it would help most people if after their flight to just take off the oil filler cap and then do other things like push the plane back into the hanger wipe off all the bugs smashed on the leading edge of the wings, cowl, windscreen , vertical and horizontal stabilizers and by that time go back and put on the oil cap. Alot of moisture comes out in that first 15 minutes. 

[Will.iam]

56 minutes ago, Pinecone said:

The Black Max does not use desicant, so you don't have to keep checking and regenerating the desiccant. 

There is one I saw recently that uses desicant, but self-regenerates.

Here it is - DryBot Automated Engine Dehydrator (rpxtech.com)

 

Just looked at that and compared it to my system it’s twice as expensive and my dehumidifier is rated for a 4000sf room. It blows out a ton of air so i don’t worry about a tight fit over the oil filler tube in fact i like that it’s blowing the excess dry air into the engine compartment getting humidity out of the engine bay area too. I’m sure my unit uses more electricity per hour as it’s an actual a/c unit using coils to capture and remove water from the air. I have a drain hose that goes out under the hanger door and drains outside the hanger. 
to give a reference to how much this thing sucks water out of the air in 4-6 hours i have 1 gallon of water out the drain. 
In fact if my hanger was better sealed i think it would just lower the whole hanger’s humidity but there are just too many drafts to lower it but maybe a few % compared to outside. 

My unit is no longer available but this is a comparable unit cheaper too! When i got mine i used the styrofoam that was protecting the top of the unit and cut out a hole where the vent blows, then i duct taped a home depot square to 4” round hole and bought 6 ft of 4” flexible duct tubing to a 4” down to 3” tube reducer and i put that 3” over the oil filler tube. I think all parts included was $500.

Amazon Basics Dehumidifier - For Areas Up to 4000 Square Feet, 50-Pint, Energy Star Certified, White https://a.co/d/4g95jbz

 

Oh and i plugged the unit into this:

WILLHI 1803-H Humidistat Digital Humidity Controller Dehumidifier Control Max 1650W 110V Greenhouse Growroom Humidity Control Outlet Humidifier and dehumidifier Mode with Sensor 0%~ 100% RH https://a.co/d/bDEacwy

[Beard]

At my airport someone was making these and selling them. I bought one. It uses an aquarium pump and has a sensor that is supposed to shut it off when necessary. I have been told that having a closed circuit is the route to go. For mine, the desiccant air is pumped through the oil filler filler tube and comes out of the engine breather tube that is located by the left cowl flap in my M20J. I attached a tube here that recycle the air.

I no longer take the expired desiccant home to put in the oven (which pleases my wife). I bought a microwave oven for my hangar that does the job of making my desiccant beads dark cobalt blue again within 3-5 minutes.

Be cautious in that if you do not have a closed circuit with an automatic shut off and you leave the devise running too long you will be pumping ambient temperature into your engine. Someone on my field had a disaster when he left his devise running for four months over the winter when he went away.

I have heard many different opinions on whether these devises actually work, but the common consensus is that they cannot do harm is used correctly. Before I hook mine up after every flight  I leave the oil filler cap off for a while to let the obvious moisture escape.

 

[Pinecone]

6 hours ago, Will.iam said:

What is amazing to me is when i first put it on right after engine shutdown just how much steam comes out in the first 5 minutes. I think it would help most people if after their flight to just take off the oil filler cap and then do other things like push the plane back into the hanger wipe off all the bugs smashed on the leading edge of the wings, cowl, windscreen , vertical and horizontal stabilizers and by that time go back and put on the oil cap. Alot of moisture comes out in that first 15 minutes. 

Most of the time, I just leave the fill cap off (hangared) and the oil door open.

But you can see the plume of steam coming out of the engine.

[A64Pilot]

On 1/22/2024 at 11:01 AM, GeeBee said:

I made my own unit with desiccant, but the BlackMax unit is appealing to me. I am glad to hear good results.

 

 

There is a name for it but I don’t know what it is.

What I’m referring to is what “good results” are you referring to? How do you know it’s even doing anything except pumping air? Does it measure RH of its output?

I’m not weighing in on if these things are effective or not, there is no way to know, you either believe or you don’t. It does seem logical that they should help prevent corrosion. However I’ve disassembled a few engines and as long as they are flown once a month or so and kept out of the rain I’ve never seen any corrosion.

I have seen corrosion, some pretty bad when for example someone gets sick and never really recovers and the airplane sits for years. 

One Twin Comanche sat in a hangar for years after the man died and his Widow finally got around to sell it, it had one cylinder with corrosion.

There is a C-140 in my neighborhood that he died after a long illness, I’ve been told that the little C-85 is gone, severe corrosion. There is a V tail Bo that flies twice every year, to and from getting its annual and I assume no corrosion.

One house has a pretty new A-36 and an Ercoupe that’s never come out of the hangar since I’ve been here. I’m wondering about them because the A-36 isn’t a cheap airplane. The man left years ago it seems, the Wife lives there and has moved her family in.

Point to all of this is unless it’s kept out in the rain so long as it’s flown at least monthly there at least in Florida doesn’t seem to be a problem. That one Bo is honestly flown to and from its annual and that’s it. I don’t know how or why it’s not eaten up.

AND if you get a long term illness either sell it or have it pickled. I pickled my C-85 and left it for over three years with no corrosion.

[GeeBee]

12 hours ago, A64Pilot said:

There is a name for it but I don’t know what it is.

What I’m referring to is what “good results” are you referring to? How do you know it’s even doing anything except pumping air? Does it measure RH of its output?

I’m not weighing in on if these things are effective or not, there is no way to know, you either believe or you don’t. It does seem logical that they should help prevent corrosion. However I’ve disassembled a few engines and as long as they are flown once a month or so and kept out of the rain I’ve never seen any corrosion.

I have seen corrosion, some pretty bad when for example someone gets sick and never really recovers and the airplane sits for years. 

One Twin Comanche sat in a hangar for years after the man died and his Widow finally got around to sell it, it had one cylinder with corrosion.

There is a C-140 in my neighborhood that he died after a long illness, I’ve been told that the little C-85 is gone, severe corrosion. There is a V tail Bo that flies twice every year, to and from getting its annual and I assume no corrosion.

One house has a pretty new A-36 and an Ercoupe that’s never come out of the hangar since I’ve been here. I’m wondering about them because the A-36 isn’t a cheap airplane. The man left years ago it seems, the Wife lives there and has moved her family in.

Point to all of this is unless it’s kept out in the rain so long as it’s flown at least monthly there at least in Florida doesn’t seem to be a problem. That one Bo is honestly flown to and from its annual and that’s it. I don’t know how or why it’s not eaten up.

AND if you get a long term illness either sell it or have it pickled. I pickled my C-85 and left it for over three years with no corrosion.

Yes, I do know. Several Beechtalk threads measuring RH. Here is one.

"I went into my hangar a took a reading of the temperature and the relative humidity (RH) using my Hygrometer. I saw a room temp of 65.8f and 33.2 RH . I then placed the Hygrometer into the oil fill pipe. It read 65.8f and showed and RH of 55.2 … higher RH than in the room … which surprised me since I haven’t flown the airplane in several days. I then inserted the tube from the Black max into the breather tube and turned it on. I came back 50 min later for another reading at the oil fill pipe. It showed 65.8f and 20.2 RH. A nice drop in RH."
 

[201Steve]

@Will.iam using a large unit, has anyone ever thought of piping lines into the engine, cabin, tail, and wings? Seems like if there’s functionality inside the engine it could keep the bones dry, too. Yeah it’s not going to be air tight but it will be majority dry air, no?

[A64Pilot]

10 hours ago, 201Steve said:

@Will.iam using a large unit, has anyone ever thought of piping lines into the engine, cabin, tail, and wings? Seems like if there’s functionality inside the engine it could keep the bones dry, too. Yeah it’s not going to be air tight but it will be majority dry air, no?

A normal dehumidifier moves a very large amount of air and the air leaks would be desirable as a way to expel the air.

It would unquestionably reduce humidity significantly, and add some warmth to the airplane.

A normal “good” dehumidifier is nothing more or less than a window unit air conditioner, the difference is the window unit discharges the warm air out outside and the cool air inside, the dehumidifier mixes both and of course as energy is being expended there is a temp rise, it’s not huge but it does add heat.

Any dehumidifier either absorbs moisture or discharges it, mine I discharge outside through a hose and it drips one drip every second, doesn’t sound like much but it was a 5 gl Home depot bucket a day before I ran the hose. Idea of a big dehumidifier is of course to blast the whole area, the kind with desiccant bags the idea is to be much more precise and pump tiny bit of very dry air precisely only where it’s needed. Either ought to work.

I don’t understand the need for the Black max to cycle. It has to be a compressor system because a peltier plate isn’t getting cold enough to freeze up, neither does a normal dehumidifier. Not saying it’s good or bad, just don’t understand why freeze and cycle, what does it do with the water it removes, there ought to be a decent amount of it when the ice melts off.

As I’ve said I dehumidify the entire hangar, 3,000 sq ft of it. My drill press table, vise etc things that used to rust no longer rust now.

It’s 93% RH outside right this minute and its 61% RH in the hangar right now with the mini - split going, it’s a warm few days in Fl right now. It will turn off before long when it hits 59% RH. It turns on at 65% and off at less that 59%.

In warm Wx like now I run the Mini-split in cold Wx I run the dehumidifier, but the RH at least in Fl is much lower than it is in warm Wx. It’s the warm muggy mornings and nights that drive it into the 90’s, when of course the dew sets it’s 100%.

Relative humidity is of course very much controlled by temps, just heating your hangar some in colder weather will drive the RH down quite significantly. I strongly suspect for you guys in the Great White North that firstly when it’s real cold it’s actually low RH and that even heating the hangar to freezing would drop it by quite a bit.

‘During a normal warm day the RH can vary as much as 100% at night to 50% during the day, the only difference is of course the temperature, if you can keep the temp swings from occurring in your hangar you can likely keep the hangar much drier. That is why I think my 60 pint dehumidifier works so well in my hangar some of its because of the dehumidifying of course but I think a large part is from the bit of heat it produces, both work to reduce RH

[201Steve]

@A64Pilot what size hangar do you have? And what kind of doors?

mine is 50x40x12, insulated roof only. I could probably seal up the walls pretty decent but the rolling door would be tough. I also have a 1.5 ton AC unit, although it only runs to my little apartment building inside. Being on the GA coast, sure would be nice to regulate the humidity some. 

[Will.iam]

It’s the ratio that is so hard to automatically control. On cold winter days the RH might be 25% and below my cutoff threshold even or in the summer with rain the RH can be 100% and my dehumidifier is lucky to pull it down to 50% and that’s running at 100% of the time. So setting my controller at on at 48% and off by 28% on really high humidity days i might have to settle with 38% cutoff or the dehumidifier will run non stop.  

[A64Pilot]

11 hours ago, 201Steve said:

@A64Pilot what size hangar do you have? And what kind of doors?

mine is 50x40x12, insulated roof only. I could probably seal up the walls pretty decent but the rolling door would be tough. I also have a 1.5 ton AC unit, although it only runs to my little apartment building inside. Being on the GA coast, sure would be nice to regulate the humidity some. 

It’s 60x50 with manual folding doors, they are metal framed and fiberglass skin panels. Building is shingle roof and concrete block. I’ve put weather stripping between the doors but the top, bottom and ends of the doors have pretty big gaps, the door is the air leak, if the door sealed well I think I could aircondition it. Pic is before I put the mini - split in, but it’s the pic I have. The big one piece hydraulic doors can be sealed very well, I’d love to have one but can’t or won’t put that kind of money into a door.

I think but don’t know that my door doesn’t meet the newer higher wind loads required by code, but neither does my garage door for that matter. I think that’s a Florida thing.

Ceiling is 12’ and I have no idea if it’s insulated or not, but I think it is, house is blown in I assume hangar is the same.

If I took a pic today it would just show a lot more “stuff”

Original plan was to put two 2 ton-mini splits in and I may do that one day, purpose of two would be if ai had a lot of work to do to turn both on the night before and they would keep it comfortable. One almost will, in the middle of Summer it’s nice until about 11 AM, from then on it gets hotter until about 2 PM it’s upper 80’s. Double cooling capacity I think would keep it bearable all day, but even though it gets hot, knocking the humidity down helps as does the 40 something inch fan.

When your Retired and the hangar is right beside the house, you tend to spend a lot of time in the hangar.

 

[RoundTwo]

In my opinion, rusting cylinders would be more of an issue than rusting cams. Everything inside the case is coated in a thick film of oil at shutdown but the cylinders should, except in my engine , have much less oil on them. It seems these dehumidification units ignore the pieces that would be the first to rust, the cylinders. Are they ignored because they’re cheaper to replace?

[A64Pilot]

8 hours ago, Will.iam said:

It’s the ratio that is so hard to automatically control. On cold winter days the RH might be 25% and below my cutoff threshold even or in the summer with rain the RH can be 100% and my dehumidifier is lucky to pull it down to 50% and that’s running at 100% of the time. So setting my controller at on at 48% and off by 28% on really high humidity days i might have to settle with 38% cutoff or the dehumidifier will run non stop.  

I went flying this morning for about an hour after the fog burned off, By the time I put the 140 in, the mooney, the go,f cart and motorcycle the doors are open I’d guess 15 min so the hangar humidity gets pretty high, right now it’s 70% and I’d assume the AC will run for hours getting it down to 60% where it cuts off.

‘I assume you’re talking about an engine dehumidifier? 50% is actually very low, but is there any harm in running one continuously? They don’t pull much power do they?

[A64Pilot]

49 minutes ago, RoundTwo said:

In my opinion, rusting cylinders would be more of an issue than rusting cams. Everything inside the case is coated in a thick film of oil at shutdown but the cylinders should, except in my engine , have much less oil on them. It seems these dehumidification units ignore the pieces that would be the first to rust, the cylinders. Are they ignored because they’re cheaper to replace?

The cylinders are sort of open to the case as the whole bottom end of them is in the case. Issue is of course the piston and rings are in the way, so it’s doubtful if any dry air makes it’s way past the piston and rings as there is no significant pressure differential.

If you have a Lycoming it’s the cam that’s “scary” though, and they would definitely dehumidify the air around the cam. Argument is, is corrosion a major contributor to cam failure? If a cam rusts it certainly would be, but except for long term storage is rust likely?

When I pickled my C-85 and left if for three years I used the preservative oil of course but also poured it into the cylinders and rotated the prop until I had oil literally running out of the carb and exhausts. I then covered the exhausts with heavy aluminum foil as well as the carb and crankcase vent. I installed desiccant plugs in the cylinders.

Plane was stored in a new T hangar in Camilla Ga. And left for three years maybe a little longer.

I got some rust in one cylinder, not terminal but enough so that cyl’s compression is high 60’s. It must have been the one that had a valve open I’m thinking. That plugs dessicant was pink meaning of course that it wasn’t working anymore.

I had both 1 and 3 cylinders off this week so I got a good look inside, zero corrosion that I could see.

Short of removing the plugs you can’t really dehumidify the cylinders

[Will.iam]

1 hour ago, A64Pilot said:

The cylinders are sort of open to the case as the whole bottom end of them is in the case. Issue is of course the piston and rings are in the way, so it’s doubtful if any dry air makes it’s way past the piston and rings as there is no significant pressure differential.

If you have a Lycoming it’s the cam that’s “scary” though, and they would definitely dehumidify the air around the cam. Argument is, is corrosion a major contributor to cam failure? If a cam rusts it certainly would be, but except for long term storage is rust likely?

When I pickled my C-85 and left if for three years I used the preservative oil of course but also poured it into the cylinders and rotated the prop until I had oil literally running out of the carb and exhausts. I then covered the exhausts with heavy aluminum foil as well as the carb and crankcase vent. I installed desiccant plugs in the cylinders.

Plane was stored in a new T hangar in Camilla Ga. And left for three years maybe a little longer.

I got some rust in one cylinder, not terminal but enough so that cyl’s compression is high 60’s. It must have been the one that had a valve open I’m thinking. That plugs dessicant was pink meaning of course that it wasn’t working anymore.

I had both 1 and 3 cylinders off this week so I got a good look inside, zero corrosion that I could see.

Short of removing the plugs you can’t really dehumidify the cylinders

When i sent my fuelpump flow divider and throttle body out for overhaul i knew it was going to be 6 weeks or longer. I put my dehumidifier on a stepladder next to the engine and wrapped the entire engine compartment and dehumidifier in  cellophane plastic wrap i left the RH sensor on top of the engine inside the wrap. The entire bubble like cocoon RH was in the low 30’s and the dehumidifier only ran a few times a day. I think i could have left it that way for storage if need be only risk would be a loss of electricity or an electrical failure of the dehumidifier. 

[Will.iam]

As this topic has come up multiple times here is the original thread where i posted pics of my setup and how it looks. 
 

 

[Will.iam]

2 hours ago, A64Pilot said:

The cylinders are sort of open to the case as the whole bottom end of them is in the case. Issue is of course the piston and rings are in the way, so it’s doubtful if any dry air makes it’s way past the piston and rings as there is no significant pressure differential.

If you have a Lycoming it’s the cam that’s “scary” though, and they would definitely dehumidify the air around the cam. Argument is, is corrosion a major contributor to cam failure? If a cam rusts it certainly would be, but except for long term storage is rust likely?

When I pickled my C-85 and left if for three years I used the preservative oil of course but also poured it into the cylinders and rotated the prop until I had oil literally running out of the carb and exhausts. I then covered the exhausts with heavy aluminum foil as well as the carb and crankcase vent. I installed desiccant plugs in the cylinders.

Plane was stored in a new T hangar in Camilla Ga. And left for three years maybe a little longer.

I got some rust in one cylinder, not terminal but enough so that cyl’s compression is high 60’s. It must have been the one that had a valve open I’m thinking. That plugs dessicant was pink meaning of course that it wasn’t working anymore.

I had both 1 and 3 cylinders off this week so I got a good look inside, zero corrosion that I could see.

Short of removing the plugs you can’t really dehumidify the cylinders

In this previous thread i show pictures of my engine compartment cocooned in plastic wrap with my dehumidifier inside the wrap as well it kept the whole engine in the low 30’s RH. 

 

[RoundTwo]

5 hours ago, Will.iam said:

In this previous thread i show pictures of my engine compartment cocooned in plastic wrap with my dehumidifier inside the wrap as well it kept the whole engine in the low 30’s RH. 

 

This looks like the best solution to prevent corrosion/rust everywhere.

[A64Pilot]

If you can get and keep RH below 50% I believe rusting of Iron pretty much stops. I cut n pasted this from one site but it’s easily searched, just search iron rusting vs relative humidity.

“Clean iron in pure air does not corrode until the air is practically saturated. However, if the air contains contaminants or pollutants, (even a trace (0.01%) of sulphur dioxide), the critical relative humidity drops to 70%. It is generally accepted that when RH is below 35-45%, no corrosion occurs.”

Except for rare instances I keep the hangar below 65% RH, and as I said my drill press table and vise etc don’t rust anymore, before I dehumidified the hangar they did. 

However almost always I fly weekly at least to Breakfast every Sun, and I think that alone should keep my engine insides clean, but being in Florida I think it prudent to do what I can to cut down on Corrosion.

Attached pic is from Fridays IA renewal class, every year Corrosion comes up, it’s probably in truth the biggest killer of GA aircraft, many accidents are repaired but often corrosion is so extensive that it’s just not repairable, even for helicopters.

I live in the green strip in Fl, so not all of Fl is bad, but the majority of Fl aircraft are kept on the coast.

 

[Pinecone]

The Black Max pressurizes the engine through the breather line, so dry air does seep past the rings into the cylinders.