Moisture in oil, Flathead V8

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mtm100

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Good Morning,

I'm wrapping up a flathead v8 project. One last nagging problem is moisture or water in the oil.
This problem is occurring on engines without a liquid cooling system and are run for short periods
of time for demo purposes. I assume that a engine run up to temperature with a cooling system would
burn any moisture off. Any advise greatly appreciated.

Thanks,
Mark
 

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Nope. 65-68F all the time. If I don't keep up with it. Makes a real mess.
 

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Don't know the answer but I wonder if it had a cooling system and could be brought up to a good operating temp the moisture might go away.

A wonderful model and runs great! Hope you will post some build pictures and let us know the resolution.

John
 
All carbon based fuels give off moisture as a by product of combustion. The engine needs to get hot enough to vaporize the moisture. It can be done without harm to the engine. Just need to monitor it close or use liquid cooling so you can run it longer to get rid of the moisture.

Ron
 
Ron is right. The problem is combustion blowby gases which are moisture laden and quickly condense in a cold crankcase. It is best to run your engine each time long enough to get it fully warmed up internally. Unfortunately it starts all over again every time you start it cold until you get the piston rings seated. Top end cylinder corrsion can occur if you don't purge the engine each time you run it. A few seconds spinning with the ignition off and throttle open clears the upper cylinders of moisture. The oil doesn't seem to cause crankcase corrosion as long as you change it when you are done running the engine. Good engine oil will hold the water in suspension. For long term storage I drain the milky oil, then flush the crankcase with WD-40, and refill with engine oil. Short use fork trucks have the same problem.
Jeff
 
Good Morning,

I'm wrapping up a flathead v8 project. One last nagging problem is moisture or water in the oil.
This problem is occurring on engines without a liquid cooling system and are run for short periods
of time for demo purposes. I assume that a engine run up to temperature with a cooling system would
burn any moisture off. Any advise greatly appreciated.

Thanks,
Mark
I know for a fact that a hot engine will cool and the moisture in the air will condense on the internals of the engine. Has to do with the hot air absorbing moisture and then dropping out as the air mass cools. So it depends on how its stored. Where you see it for the average guy is in his fishing boat outboard being stored for winter. I guess I would store it with a desiccant in a special container but I have no idea how practical that would be for you.
 
As Ozzie46 observed, it's a universal problem. I see it the worst in the igniter on my Red Wing 1/4 scale. This engine runs cool forever, and at the end of a show I have to disassemble, dry, and oil coat the ignitor and its cavity in the cylinder. Otherwise, all the iron and steel parts rust like crazy. I suspect the condensate has some other stuff in it that makes it more corrosive than just plain water.
 
I will just throw this out to you. Do you have a crankcase breather on the engine or any other way for vapors to escape along with moisture. If you don’t then you will build up crankcase pressure and it will kill the engine. But it allows moisture to escape from the engine. It looks like to me that is oil on top the pistons and coming from behind the valves of them are the intake valves you are showing. This could all be a sign of positive ccop ( positive crank case pressure. Just throwing it out there
Thanks
Tom
 
Thanks guys. Some very good advice presented already.
But I shall add my pennorth, FYI. (I worked with the chemist making the recipe for motor oil during part of my career).
A university Doctor advised that "The oxidising properties of ferrous materials used commonly in our modern lives can be summarised in 2 words. - Steel rusts."
That said, the combustion gases are a horrible mix of organic and inorganic materials. Water, CO2, CO, N2, and Nitrous oxides. Also from the spark, a very tiny amount of O3. (Ozone). That makes a corrosive mix that rusts steel quickly.
The temperature, and pressure in the combustion cause some of these gases to dissolve in the water as it condenses (cooling and pressure drop causes condensation). Typically, a gallon of fuel makes more than a gallon of condensate - allmost all of which goes out the exhaust pipe. But something like 0.1~1% goes past the piston rings as blow-by gas. Cars always take this down a hose to the intake manifold and pass it through the engine to clean it in the combustion chamber and throw it down the exhaust.
But the condensate from blow-by gases mixing with oil are very acidic - they really rapidly combine with easily corrodable metals. Motor oils, unlike most other oils, are heavily loaded with
  • detergents (to hold moisture in suspension and prevent it puddling in the sump.... - which could cause a bubble of water to be pumped through bearings with disastrous results, etc. - and permits the emulsion to carry the water to hot parts of the engine (above the valve gear in the cylinder head) where the water can be boiled-off and vented through the blow-by valve and pipework).
  • Anti-acid stuff - typicaly zinc compounds, etc. - that counteract the gases dissolved it condensate water that make it acidic.
  • Lubricant enhancers - solids dissolved in the oil that are deposited on bearing surfaces under high stress or when oil drains from surfaces, that prevent scuffing if the oil film breaks down, or for cold starting. The durability of engines left standing is enhanced by the anti-scuff compounds, but theses can be washed away by WD40, etc. so the oil film must be replaced after cleaning.
  • Waxes and surface tension improvers, which help maintain some oil at a surface which keeps air and condensation from the surface, prolonging the oil film protection.
But valves in combustion chambers are usually clean of oil.
I have a cast iron frying pan. After washing, cleaning scouring to the fresh metal surface, it will rust overnight on the kitchen shelf. A very thin film (wipe ) with oil will prevent rusting. But on the outside, it has developed a lacquer from flames from the gas cooker, burning oils and fats vaporised during cooking and drawn into the gas flame. The black lacquer is very good at preventing corrosion. Decades ago we used to have to de-coke engines regularly, as this lacquer was detrimental. A product of the dirty combustion and combustion of a tiny amount of engine oil off the bore. But the lacquer we de-coked, did prevent valves and cast iron heads and seats from rusting!
I hope some of this helps?
K2
 
Last edited:
Thanks very much for the replies.I think the no spark, no fuel cranking might be the trick.
 
One thing I didn't mention is the silver engine was the first built. And the test bed for lots of run time and or abuse.
It has hundreds of hours of run time. Seized 3 times but always cleans up to run another day. The red engine is a newer build
with much less run time so moisture problems are less evident. I'll give the oil in the fuel and no fuel cranking a try for a while.
Problem is I run these most every day. Looks like I should work on a cooling system soon.
Thanks Again for all the advice.
Mark
 

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You could always drain the oil and heat gently to drive off the water... Like a chip pan, you'll hear it crackle when it has emulsified water in it, when over the boiling point for water, but kept at 120C or so (so the oil does not break down) for a half hour perhaps should dry the oil suitably.
If oyu try the cranking without fuel, you should ensure adequate lubrication. And a spray of "duck oil2 or other corrosion inhibitor down the intake will not go amiss, but you may need to clean the spark plug before the next run! You do NOT want any carbon containing substances on the spark plug insulator, as that will eventually cause early life failure as it flashes over. A spray of "carb cleaner" should be adequate on the spark plug.
K2
 

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