Run it dry at full throttle. Don't leave it in a place with uncontrolled temp
and humidity. Worked for me for 25 years.
Dr.1 Driver
"There's a Hun in the sun!"
Run the fuel out of the engine so there's none left in the crank case.
After you drain the tank, pull the fuel line off the carb and try and start
the engine. If it starts, it will only run for a few seconds. If it won't
start, just keep flicking the prop until it doesn't 'pop' anymore. I like
to use After-Run oil in my 2-strokes (the stuff I've got is branded
'Hobbico'). Put several drops down the carb (try not to get it on any
rubber bits like o-rings....I'm told it's not good for them for some reason)
and flip the prop half a dozen times to make sure it works its way to the
bearings etc. I store my engines so they aren't sitting
nose-down.....anything left in the crank case will run to the back of the
engine, instead of pooling in the bearings. Not sure if this makes any
difference, but I figure it can't hurt :-)
MrBonk
Hi,
There are two elements that combine to make after-run maintenance a good
idea. The alcohol in our fuel is hydroscopic (absorbs water from moisture
in the air) and some acids are formed during the combustion process. Modern
fuels contain additives that help reduce the acid products, and the
lubricants do a much better job of producing a film on the internal
components. From a technical point, the best of both worlds from the
lubrication standpoint should be fuel that contains a mixture of synthetic
lubricants and good old Castor. The synthetics should have superior
"lubrication" qualities and the Castor fortifies the "oil" content during
the high temperatures encountered in our small engines.
It is always a good practice to "run the engine dry" after the last flight
of the day by pulling the fuel line while the engine is running at about 25%
to 50% throttle. Then flip the prop through with the glow driver attached
to get as much fuel out of the engine as possible.
Both our 4-C and 2-C engines rely on fuel/oil mixture in the crankcase to
lubricate the internal components. With 2-C the fuel/oil enters the
crankcase directly from the carb. With the 4-C engines, the fuel/oil
mixture lubricates the internal components through piston "blow-by".
Regradless of the engine type, there is oil and some fuel in the left in the
crankcase after the run. The biggest down-side to this is that the moisture
absorbed by the alcohol in the fuel tends to remain against the bearings
after the alcohol has evaporated. The "run dry" procedure will remove a lot
of the un-used fuel and reduce the probablility of corrosion. However, a
good "after-run" oil can further decrease the possiblility of both corrosion
and "gumming" of flight lubricants left in the case. The "gumming" problem
is most evident with 100% Castor fuels in engines stored for long periods of
time.
In humid climates, or seasons, the possibility of water corrosion is the
worst. I currently live in an are where the humidity is very high 12 months
out of the year and rarely below 90% during the summer months. Tools "rust"
even when stored in "dry" garages. That is why I always use an "after-run"
oil after the final flight of the day - even if I am going to fly the
following day. In "dryer" climates, the problem is not so severe.
The commercially available "after-run" oils are good. But, are more
expensive than "home-made". You can make a darn good after-run oil in
larger quantities and for less money per ounce than the commercial stuff.
Go to a good autoparts store and buy a can of "Marvel Mystery Oil" and a can
of automotive transmission fluid. Mix the two components together 50/50 in
a separate container that fits easily in your flight box. The best of the
Marvel Mystery Oil product line for this application is their "air tool oil"
because it is especially formulated to deal with the water that condenses
out of the presurized air being fed to the tool. But, it tends to be more
expensive and harder to find than the base product "Marvel Mystery Oil".
The base product works just fine for our use.
I have been flooding my engines with this mixture as an after-run oil for
over 30 years and I have never had a problem with corrosion on any of the
steel parts and bearings. And, I have never had to tear down or soak an
engine, that I have stored for years, to remove "gum" from oil flight oil.
J
I disconnect my fuel line, open the throttle, attach the glow driver, and
give it a spin with my starter to burn out any fuel remaining in the engine.
I remove the glow driver and put two or three drops of Marvel Air Tool Oil
down the carb throat and spin it again. On 4-strokes, I run the oil down
the crankcase pressure vent line.
--
Morris Lee
snipped-for-privacy@verizon.net
Run it dry at full throttle with castor in the fuel. Keep the fuel line
pinched or removed from the carb until the tank pressure has bled back
through the muffler. With castor, after run oils are redundant :)
Newbee wrote:
Run it dry then add some after run oil -- I always use Marvel Air Tool Oil.
Cheers -- \__________Lyman Slack_________/
\______AMA6430 IMAA1564___/
\____Flying Gators R/C______/
\__Gainesville FL _________/
Visit my Web Site at:
I would debate the assertion that there is any significant fuel left in the
crankcase after the engine is shut down. The engine remains very warm for a
long time and any fuel is completely vaporized. Add to that the fact that
two stroke engines are open to the air unless you rotate the prop until the
exhaust port is closed and leave it there.
More than likely the rust comes from garage storage of engines in humid
climates where temperature swings cause expansion and contraction of the air
inside the engine. This allows more moisture to collect. Engines in drier
climates, like Arizona, tend to have almost no rust problems.
I left a Como .51 in the trunk of the car sitting in the driveway one summer
night (after flying that day). The bearings were rusted the next morning.
Since then, I've always stored my engines in a climate controlled room. No
problems.
Dr.1 Driver
"There's a Hun in the sun!"
That speaks of a metallurgy problem. I have bearings that have sat in my
garage in the UK for three years with no signs of rust. These are bearings
that were removed from various engines. No after run oil ever saw those
bearings.
My experience: for many years I did as Clarence Lee said, running the
engine dry and adding "after-run" oil, and it seemed like I replaced
bearings more often than anyone at my field. So, as an experiment, I
stopped using the oil. I do run the engine dry, meaning I start it
repeatedly until it won't even pop. I use fuel with 80/20 oil, so
there is residual castor oil. After two years, haven't had any trouble
with any of my engines. I live in a humid climate (SW Florida, near
the Gulf). This may not make any sense, but that's what I have found.
Can't do it with the helicopter (unless I hang it upside down from the
ceiling by the skids!!). Mind you, leaving it sitting on the skids (crank
facing straight up) didn't stop the bearings in *it* going rusty, although I
suspect that had more to do with where it was being stored at the time
(unsealed, non temp-controlled garage). I replaced 'em with stainless steel
ones, so no more rust since :-)
MrBonk
Just how did those combustion gases get in the crankcase of a two
stroke? Nada. The acid you are refering to is nitric acid and reacts
with other combustion by products immediately and you have to be
running over 80% nitro to have any substantial amount.
This is my experiance also. After run oil, rusted bearings, no after
run oil, rusted bearings.
The only after run oil that works is castor oil. That is because the
petroleum oil does not mix with water and floats on top of it. The
water with disolved air then rusts your bearings. Also, don't store
the engine nose down, water is heavier than oil and the water droplets
will work their way down into the bearings.
> > Run it dry at full throttle with castor in the fuel. Keep the fuel line
> > p> > > HI all - what the best post-run maintenance for a 2 stroke engine after a
> > > run? Thanks again...
> > >
> > >
>
> My experience: for many years I did as Clarence Lee said, running the
> engine dry and adding "after-run" oil, and it seemed like I replaced
> bearings more often than anyone at my field. So, as an experiment, I
> stopped using the oil. I do run the engine dry, meaning I start it
> repeatedly until it won't even pop. I use fuel with 80/20 oil, so
> there is residual castor oil. After two years, haven't had any trouble
> with any of my engines. I live in a humid climate (SW Florida, near
> the Gulf). This may not make any sense, but that's what I have found.
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