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Winter operations / lowest temperature for starting / preheating methods (merged)

We have this one and are really happy. I installed it myself under the supervision of my A&P. There is a band around each cylinder and two of the “power resistors” glued to the engine (with high temp epoxy). In total it puts 400W into the engine. We have installed a switch which can be operated by a text message via the phone. I’d say on a cold day it takes about 6 hours to throughly warm the engine. When we switch it on before we go to bed, we see about 75F the next morning, even on very cold days (however, Mannheim is not a very cold place).

EDFM (Mannheim), Germany

I use two regular “home electric heaters” 2KW each for my Seneca. In non heated hangar it takes one full hour to raise the engines from +1C to +24C. I take a temp reading by inserting a 20cm wire probe in the engine oil tube.
I have slim heaters and position them inside the cowling (through a cowflap) they blow directly into an oil sump and as the heat goes upwards – all cylinders become warm as well (90-120F on EDM). I think that placing the heater at the bottom of the engine is much better because of the convection.
Now it becomes interesting:
My probe measures temp and humidity. I use engine dehumidifier made by myself. Very simple. Air pump, air filter, box with silcagel, and plastic pipes connected to both crancase vent pipes. The idea is to slightly pressurise engines with dry air, which pushes away the moisture.
It works. The probe reads about 30-40% humidity after short time. But when I plan to go flying, after disconnecting dehumidifier when the preheating starts – the humidity inside begins to rise! To about 95-99%!
I guess it is the moisture diluted in the oil (although it looks perfectly clean!) and gets released to the crancase.
So I am against a constant heating device as it can do more damage than good.
I the engine manual it even says somewhere that preheating for more than 24 hours can do severe corrosion attack. I agree with that.
In my opinion after flying the engine should be cooled down and connected to a dehumidifier as after flight it is usually 100% humidity.
The colder the engine is – the longer it takes the oil to flow off the components.
At least in my Seneca which is designed to fly high where the cooling is hard and when flying low it is constantly below 170F oil – even with oil cooler fully covered.
The problem however comes outstation – when no electrical power is available to preheat.
I am using W100Plus and prefer do preheat below plus 15C.

Poland

Raven wrote:

I guess it is the moisture diluted in the oil (although it looks perfectly clean!) and gets released to the crancase.

I think there was a test done once by tanis or reiff. I don’t remember which one. The test did not recommend engine heaters to be left on all the time without a dehumidifier. Exactly in line with your findings, the heating would release moisture from the oil and all that moisture ends up condensing on the cold parts like crankshaft, cylinder walls etc.

I have a “homebuilt” heater in my hangar. It blows warm air through the front landing gear doors. I leave the cowling plugs on and cover the cowling with an emergency blanket (space blanket), gold side facing outwards. The space blanket is incredibly effective in reflecting the heat back into the cowling. With a 2000w heater, it only takes about 45-60min to raise CHT from 0C to about 18-20C.I prefer heating everything uniformly inside the cowling with hot air than using cylinder head and oil pan bands.

The problem is when travelling. I am quite religious about pre-heating but there is hardly any chance to preheat when you are far away parked somewhere in small airfield.

Switzerland

“In my opinion after flying the engine should be cooled down and connected to a dehumidifier as after flight it is usually 100% humidity.”

I believe you can improve the situation a lot by opening the refill cap and let the hot oil breathe out the vapor while doing all post flight tasks…

...
EDM_, Germany

ch.ess wrote:

I believe you can improve the situation a lot by opening the refill cap and let the hot oil breathe out the vapor while doing all post flight tasks…

I do it every time! :)
I leave it open for an hour or sometimes more immediately after flying.
You can see the steam flowing up from the oil refill. There are water droplets on the inner side of the caps.
Does’t help. Still 100% when I return next day or even after one or two weeks of inactivity.
Dehumidifier is the only solution I can see to reduce big amount of water in the crancase.
Before flying one hour of preheat.

Poland

Definitely steam comes out, but if one leaves the plane like that, unattended, the dipstick might get stolen

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

but if one leaves the plane like that

Only in a closed hangar. :)
Dipstick sits in place. I have a separate cup, which is on a chain :)

Last Edited by Raven at 14 Jan 18:44
Poland

How would you leave your plane unattended during post flight routine ???
I naturally put everything back on after completing the tasks and pushing her in the hangar.

No time unattended ;-)

Last Edited by ch.ess at 14 Jan 22:00
...
EDM_, Germany

I soon will be changing to W80Plus (from W100Plus) for winter season.
Don’t like 15W50. I try to stick to monograde.
We’ll see if there is any difference in oil press/temp. etc.
W80 should save the engine a bit more than thick W100 when outstation and no preheating is available.

Poland

This may be relevant to the oil discussion.

In most European GA scenarios, preheating is not feasible due to “airport political” restrictions. I think if you have a hangar and can use electric power in there, it is dead easy to simply rig up a warm air blower and poke it into the air intake(s).

Administrator
Shoreham EGKA, United Kingdom
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