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Engine Preservation. Cheap, hopefully effective apporach

Freemasm

Well Known Member
My Titan Engine is supposed to be preserved. It's been out of the desiccated bag a a few months now as I flounder with baffles, firewall component layout, cowling, etc. Can't over-fill the engine with oil until after I install the governor (on order) so working in circles as always.

Already had desiccant plugs installed in the cylinders. Got nervous and attempted to desiccate the engine ullage space. Utilized three sizes of vinyl tube (7/8" ID down to 1/2" ID) from the STC/PMA aisle of Ace hardware nested together/sealed down to a 1/2" nylon barb connection. There's less than $20 in this including the lb of reusable desiccant (from ACS).

Cheap = Big yes
Effective = Should be. We'll see. The worst thing that can happen is if the desiccant never indicates.

Before someone points out the lack of an air pump, etc. gonna say that equilibrium is a wonderful thing.

The desiccant dries very easily in the oven. Already done it a few times for the plugs. Here's a pic of the cheapa$$ dryer laying on the mount. Will secure it with a velcro strap. I'll update on perceived effectiveness if anyone wishes. Powerplants aren't getting any cheaper.
 

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Same problem

I have the same problem with my engine. I am hoping the the oil vapor in the crankcase is enough to keep the inside clean as long as all the holes are covered.
 
In my hangar, my airplane is on a dehydrator 24/7. A $20 aquarium pump (not willing to hope for "equilibrium", nor oil vapor) pushes air through a dessicant chamber (airtight food canister filled with silica gel) and out through a tube to a rubber stopper plugged into my dipstick tube. Continuously pumps air with a relative humidity of 10-15% through the crankcase. Simple, cheap, and quiet. Efficacious? No clue, there is no such data, but I think it's reasonable to assume that if I eliminate water in the crankcase by keeping the dew point well below the ambient temperature (by decreasing humidity), I will minimize corrosion since water is necessary for corrosion to occur.
 
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Looks like a good solution! I'd put as much oil in there as you can, and just plug up any openings with covers or tape.
 
In my hangar, my airplane is on a dehydrator 24/7. A $20 aquarium pump (not willing to hope for "equilibrium", nor oil vapor) pushes air through a dessicant chamber (airtight food canister filled with silica gel) and out through a tube to a rubber stopper plugged into my dipstick tube. Continuously pumps air with a relative humidity of 10-15% through the crankcase. Simple, cheap, and quiet. Efficacious? No clue, there is no such data, but I think it's reasonable to assume that if I eliminate water in the crankcase by keeping the dew point well below the ambient temperature (by decreasing humidity), I will minimize corrosion since water is necessary for corrosion to occur.

Figured on this one. The principle equilibrium is a fact (some say force) in nature and especially important in fluid chemistry. It is not a "hope". Also, no one suggested oil vapor as a motive force for moving air. Vapor Space Inhibition, oil/oil vapor being a common medium, is also a well known and practiced form of corrosion protection. That said, enclosed spaces tend to "breath" with temperature changes so that method has limits.

I've designed plenty of oil dyers for steam turbine lube oil systems. Via vacuum dehydration, < 2% of the total system flow is actually processed/dried to just a few ppm of water. Equilibrium takes the rest of the oil supply to well below the target of 40ppm. A closed system and a very efficient and more complete process compared to others.

Of course, utilizing a pump will speed up your process initially. From your description, you have a once through system. I assume there's a way to inspect the condition of the silica gel inside of the sealed container. Wouldn't take long to saturate the desiccant here in Humid AF Florida. BTW, if you're utilizing gel you are relying upon equilibrium to distribute the moisture throughout the gel as only a small fraction of it is actually exposed to the process air. If you really wanted a super dry case, you could extract through the dip stick and reintroduce the dry air though the breather. Depending on the type of desiccant you're using, it could oil fowl so choose wisely.

Glad you're protecting your investment. Don't assume yours is the best way for everyone.

Edit = @ Mickey, it's full up to the governor boss. That still has to come off. Everything is plugged/sealed.
 
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Glad you're protecting your investment. Don't assume yours is the best way for everyone.

LOL. I don't assume that. I don't even know if dehydration affects engine corrosion at all. There is no data for the efficacy of my approach to engine preservation (nor yours ;)), only inductive reasoning. I use this dehydration method solely because it's cheap and easy...can't hurt, might help. Pumping it in rather than equilibration makes more sense to me, so I do that.

And yeah...a closed system would likely be more efficient, at least in terms of having to bake the gel less often. As it is, I use 8 lbs in some kind of food container and have to bake it about every 6 weeks. It indicates by turning orange but I more often base its status on the actual measured humidity in the chamber. More than 15% and it's time to hit the oven.

I set the thing up to be a closed system, pumping dehydrated air in through the dipstick tube and recovering that air with the pump intake plugged into my oil separator. In practice, it was too much of a PITA to get on my back to slip the tubing over the separator after each flight, so I don't do that. Maybe if I lived in Florida I would.
 
LOL. I don't assume that. I don't even know if dehydration affects engine corrosion at all. There is no data for the efficacy of my approach to engine preservation (nor yours ;)), only inductive reasoning. I use this dehydration method solely because it's cheap and easy...can't hurt, might help. Pumping it in rather than equilibration makes more sense to me, so I do that.

And yeah...a closed system would likely be more efficient, at least in terms of having to bake the gel less often. As it is, I use 8 lbs in some kind of food container and have to bake it about every 6 weeks. It indicates by turning orange but I more often base its status on the actual measured humidity in the chamber. More than 15% and it's time to hit the oven.

I set the thing up to be a closed system, pumping dehydrated air in through the dipstick tube and recovering that air with the pump intake plugged into my oil separator. In practice, it was too much of a PITA to get on my back to slip the tubing over the separator after each flight, so I don't do that. Maybe if I lived in Florida I would.

It is helping and not just with preventing corrosion from the more obvious sense. Engine oils (being generic here) like to absorb water and become acidic. Secondly, water and oil do mix contrary to the saying. The light lubricating oil I previously mentioned is typical and would usually be ~200ppm water out of the barrel. It had hydroscopic tendencies to want to hover around 80ppm before bulk water would be visible. The suspended, invisible, water would still greatly accelerate bearing wear; parts intended to have 100k hour operating life before OH. Same thing in our powerplants; adding one more destructive ingredient to start-up, warm-up before it boils off. Keep it dry.

As my build is moving seemingly at a snail's pace, I began doubting if the OEM preservation was going to be enough.
 
Engine oils (being generic here) like to absorb water and become acidic.

Oil is NOT hygroscopic, like glycol. It will not absorb water, though it can hold very small water particles in suspension for moderate periods of time due to it's strong surface tension. Eventually it will fully separate. Also, oil does not hold acid well either. The real issue is that the moisture held in suspension can mix with combustion byproducts and become a new acidic compound. That new compound will become thick and stick to various engine parts instead of simply evaporating like the pure H2O does. This is why we strive to get moisture out of the oil as quickly as possible and frown upon engine runs that are not long enough to get hot enough to get rid of that moisture before it combines and makes bad stuff.

Ever pulled the oil cap off a car that only gets grocery store runs. You will see that milky white or tan goo stuck to it that looks like mayonnaise. That is the compound I am referring to. Sorry, not a chemist so cannot articulate in scientific terms. I just know that it is water mixing with combustion byproducts and the result is thick / gooey and quite acidic once the moisture evaporates out of it.

The corrosion issues in our Lyc engines is not from water in the oil. It is from the oil dripping off the parts over time and leaving them exposed to moisture in the air. This is why engines run frequently don't have problems; Engine doesn't sit long enough for oil to drip off (5-30 days depending upon who you ask). Fogging oils work, not because they remain a fog, but because they are very thick and have a MUCH greater surface tension and will not drip off the parts, thereby protecting them from atmospheric moisture. However, they don't lubricate well and that is why they must be drained before starting. Corrosion in a manual transmission or differential is pretty much never seen, as they use a 90 weight oil that doesn't drip off easily like engine oil. They also use cling additives to increase surface tension.

Larry
 
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Oil is NOT hygroscopic, like glycol. It will not absorb water, though it can hold very small water particles in suspension for moderate periods of time due to it's strong surface tension. Eventually it will fully separate. Also, oil does not hold acid well either. The real issue is that the moisture held in suspension can mix with combustion byproducts and become acidic. That new compound will become thick and stick to various engine parts instead of simply evaporating like the pure H2O does. This is why we strive to get moisture out of the oil as quickly as possible and frown upon engine runs that are not long enough to get hot enough to get rid of that moisture before it combines and makes bad stuff.

Ever pulled the oil cap off a car that only gets grocery store runs. You will see that milky white or tan goo stuck to it that looks like mayonnaise. That is the compound I am referring to. Sorry, not a chemist so cannot articulate in scientific terms. I just know that it is water mixing with combustion byproducts and the result is thick / gooey and quite acidic once the moisture evaporates out of it.

The corrosion issues in our Lyc engines is not from water in the oil. It is from the oil dripping off the parts and leaving them exposed to moisture in the air. Fogging oils work, not because they remain a fog, but because they are very thick and have a MUCH greater surface tension and will not drip off the parts. However, they don't lubricate well and that is why they must be drained before starting. Corrosion in a manual transmission or differential is pretty much never seen, as they use a 90 weight oil that doesn't drip off easily like engine oil.

Larry

Always good to hear from you, Larry. I always read your posts. Always very insightful and knowledgeable but I'm gonna have to disagree with you on this one, Maybe your definition is on the micro versus macro level but hear me out.

Stolen definition from Wikipedia = Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance's molecules, adsorbing substances can become physically changed, e.g., changing in volume, boiling point, viscosity or some other physical characteristic or property of the substance.

Some (most?) oils do exactly that. there's no reference to chemistry, reactions or anything else on the micro scale. As mentioned, the happy point for Mobile DTE lite was around 80ppm. Our course measurement of H2O content in said lube oils was the change in electrical capacitance IIRC (??conductivity, been too long ago). Then a water/steam chemist would get involved if the test failed at the technician level. This also affected the oils pH level. Thinking back, maybe I was making assumptions here. If the acid level changes were only present on the gas turbines, it would be easily explained away as there was a bearing in the turbine exhaust tunnel. My specific reference is the steamers were there is no combustion or related byproducts in that part of the cycle.

I'm well aware of the need to avoid short ICE runs. Getting the oil above the local H2O BP for x-time is crucial. That was the beauty of vacuum dehydration; you rarely needed to heat the oil (above it's return temp) to flash the water at those low pressures. Anyway, for a change I'm not in agreement with you here. It may be my ignorance, but aligns perfectly with my experience and rationale. PM me if you want. Always willing to learn though not always good at it.
 
Always good to hear from you, Larry. I always read your posts. Always very insightful and knowledgeable but I'm gonna have to disagree with you on this one, Maybe your definition is on the micro versus macro level but hear me out.

Stolen definition from Wikipedia = Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance's molecules, adsorbing substances can become physically changed, e.g., changing in volume, boiling point, viscosity or some other physical characteristic or property of the substance.

Some (most?) oils do exactly that. there's no reference to chemistry, reactions or anything else on the micro scale. As mentioned, the happy point for Mobile DTE lite was around 80ppm. Our course measurement of H2O content in said lube oils was the change in electrical capacitance IIRC (??conductivity, been too long ago). Then a water/steam chemist would get involved if the test failed at the technician level. This also affected the oils pH level. Thinking back, maybe I was making assumptions here. If the acid level changes were only present on the gas turbines, it would be easily explained away as there was a bearing in the turbine exhaust tunnel. My specific reference is the steamers were there is no combustion or related byproducts in that part of the cycle.

I'm well aware of the need to avoid short ICE runs. Getting the oil above the local H2O BP for x-time is crucial. That was the beauty of vacuum dehydration; you rarely needed to heat the oil (above it's return temp) to flash the water at those low pressures. Anyway, for a change I'm not in agreement with you here. It may be my ignorance, but aligns perfectly with my experience and rationale. PM me if you want. Always willing to learn though not always good at it.

You sound far more knowledgeable than I, so will defer to your expertise. I was always instructed that oil and water DO NOT mix and have seen it proven several times. However, that is not a lab or done at the microscopic level so I must defer to those in the trade.

I still believe that the acid is formed by combination of water and combustion byproducts and even saw the chemistry at one point, but cannot remember the details. Still true if that water is encapsulated in an oil substrate. I don't believe that oil is becoming acidic, instead the water is combining with things and the new compound is acidic, even if held in suspension in the oil.

I still believe that the corrossion seen in our engines is coming from the atmosphere and not the oil, but have no science to back that up. If the minute water particles are fully encapsulated in oil, it would stand to reason that water cannot cause corrosion or at least on any meaningful level, as the moisture must come in contact with the metal in order to start the oxidation process. Only anecdotal data showing that weekly engine running significantly reduces the chances of cam spalling over those run monthly or longer. The cam gaurd guy did several experiments related to time for oil to drip off metal parts, thus exposing them to atmo moisture. He claims a 4X improvemnt in cling and he believes that once the oil is gone, corrosion can start from atmo moisture.

Larry
 
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I have doubts as to the need for all this hand wringing over moisture. I may be vastly wrong.
But I have in my closed, insulated, and sheet rocked hangar an overhauled 0-360 that was ground run 7 times, for total 4.1 hours 25-30 years ago. The seller got to old and decided to not fly the aircraft and donated the airframe to a museum.
It was stored vertically on an engine stand and kept by the guys furnace for 12 years, I bought it and have had it hanging in a normal operating position on an airframe in my hangar or shop since. No oil in it. Actually I took it off and put it on an engine stand to rotate it upside down, remove the sump, and have another look at the cam, You can see the front three lobes.
I did fog the cylinders 15 years or so ago.
No top plugs and now no bottom sump.
I bore scoped the front cam lobes and cylinders a few months ago. It has a used cam in it and new pistons as far as I can tell.
I have seen no rust, corrosion or anything unusual going on.
I intend to roll the engine upside down and fill with a bit of oil to relube the cam before I re-install on the airframe.
But it probably won't be fired up for another year or so.

So that's my story and I'm sticking to it.
If you store an engine outside or in an open shop, all bets are off.
The RV-6A I0-360 550 hours cs prop is kept in my hangar flown 75 hours a year, oil changed 25-30 hours gets no special treatment except pulling the dipstick out while it sits. I'm not worried about corrosion.
I was a line auto mechanic for a few years way back and seen all the white foam oil on fill caps and dipsticks, so I have seen the gunk.
Your mileage may vary. Art
 
There are always outliers to any data sample. Sometimes luck is involved. I'm convinced through anecdote that the older components had better properties and/or quality in many cases despite their older manufacturing processes. That's another debate over a cold adult beverage. Can assure you anything exposed to Flor-i-dah weather won't make its expected life. If not the humidity, the intense sun will destroy it.

Larry's mostly right; or, I might be. Doesn't matter. It's easy to put 50, 60, $80K into a powerplant these days. That won't be coming down significantly anytime soon it would appear.

My original point; protect your investment, protect your investment, ...

A possibility is to buy an engine dryer. If you don't want to spend a lot, build a desiccated air blower like McCool. If you want to spend almost nothing, close it off and connect a desiccant jar to it. Lot's of other ways. Just do something.
 
Update

Update if anyone cares. Got lazy and was removing dessicant from the engine breather to replace that of the plug dryers; so, the engine dryer beads are about 1/2 the amount that I started with last June.

The dessicant did show moisture absorption. As mentioned, the worse thing that could happen would be to never show any indication. Now I know.

Anyway, while it still had some life left, I changed the beads today. See pix. The process is slow and the related bad effects even slower but I still believe it shows benefit. Less than $20 invested including the dessicant. Cheap protection.
 

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