Is it okay for plane to sit for a few weeks?

[Taltruda]

Originally Posted by SwimmingDragonfly96

Is there anything about aircraft pistol engines that make them any different than automobile engines in regards to corrosion while sitting? I’ve had cars and motorcycles sit around for quite some time and fire right up as long as the battery was charged (and carbs weren’t gummed up on motorcycles).

Another question, does 100LL prevent gumming up of gas that’s seen in carbs of motorcycles that use auto gas? I see a lot of posts about corrosion, but never see anyone posting about cleaning gummed up carbs, etc.

Thanks VAF brain trust.

100LL doesn’t seem to gum up.. I’ve ferried an airplane with years old gas and it started right up.. as for the rest of the engine, perhaps it’s the short exhaust pipes that let in moist air, or the metals used are more prone to corrosion, idk, but the cam on Lycoming engines sits on top and seems like the most likely thing to corrode. Continental engines have the cam below and they seem to corrode less..

[Taltruda]

Originally Posted by SwimmingDragonfly96

Due to weather and travel, I don’t think I’ll be able to fly my new to me 7a for about 3 weeks total (one week in now). I know planes sit for months to years sometimes and their motor is fine, while others in similar conditions will develop problems.

I could go over to the hangar and ground taxi it for some minutes to get everything flowing, but I’ve heard this doesn’t do much to help the motor. What are your opinions? Should I let it sit or go taxi it for a bit?

Leave the keys with your buddies and let them fly it!!

[SwimmingDragonfly96]

Originally Posted by Taltruda

Leave the keys with your buddies and let them fly it!!

What keys??

[BillL]

Originally Posted by SwimmingDragonfly96

Is there anything about aircraft pistol engines that make them any different than automobile engines in regards to corrosion while sitting?

Another question, does 100LL prevent gumming up of gas that’s seen in carbs of motorcycles that use auto gas?

Auto engines have the following that is different.

1. positive crankcase ventilation that pulls clean, filtered air through the crankcase. This keeps the water (a key product of combustion) out of the air so for cars that driver far enough to get up to operating temps, it keeps the air cleaner. The highest dew point is equal to ambient air. Aircraft start with a 180F dew point and condense water every shutdown.
2. Auto gas has about 20 times less sulfur than 100LL. Sulfur and water make acid in the crankcase.
3. Air/fuel controls on the auto engine substantially reduce excess raw fuel in the blow-by.
4. Since emissions drive reduced low by, there is less volume for the system to neutralize.

All of these reduce basic contributors to crankcase conditions that promote corrosion after 3 weeks. Camguard shows it can extend that time.

100lLL is very stable and has a low vapor pressure, auto gas is not.

[MacCool]

Originally Posted by BillL

All of these reduce basic contributors to crankcase conditions that promote corrosion after 3 weeks. Camguard shows it can extend that time.

"Theoretically", so does an engine dehydrator by continuously keeping the dewpoint well below ambient humidity, as well as flushing any post-shutdown moisture-laden air, exchanging it for dry air. Cost me about $45 to build...can't see a downside.

I can't speak to Camguard...many people are convinced that it's a good addition. I use it on the premise that there's likely no downside, and a lot of smart people think that it might help.

[BillL]

Originally Posted by MacCool

"Theoretically", so does an engine dehydrator by continuously keeping the dewpoint well below ambient humidity, as well as flushing any post-shutdown moisture-laden air, exchanging it for dry air. Cost me about $45 to build...can't see a downside.

I can't speak to Camguard...many people are convinced that it's a good addition. I use it on the premise that there's likely no downside, and a lot of smart people think that it might help.

Mac, we are in complete agreement - the dryer is the most effective, but I was addressing the OP's question as to why cars don't have the same issues. Also he parked the plane and all the water and acids condensed already, so a dryer will have to work for a long time to get it cleared. That is why I adopted the 5 min purge while the engine is hot.

I have been using dehydrators for 10 yrs. I am working on a 4th generation with a Peltier device and electronic control to periodically stir the crankcase pot and measure humidity.

[MacCool]

Originally Posted by BillL

Mac, we are in complete agreement - the dryer is the most effective, but I was addressing the OP's question as to why cars don't have the same issues. Also he parked the plane and all the water and acids condensed already, so a dryer will have to work for a long time to get it cleared. That is why I adopted the 5 min purge while the engine is hot.

I have been using dehydrators for 10 yrs. I am working on a 4th generation with a Peltier device and electronic control to periodically stir the crankcase pot and measure humidity.

A more high volume purge is a good idea IMHO. Based on a post I saw on here a few years ago (might have been yours), I use a 12v pool toy inflator in through the dipstick tube for a few minutes after shutdown while I'm pushing the plane back into the hangar, then hook up the lower-volume dehydrator before I leave.

I agree with you about auto engines. No question that the dinosaur-era technology of most aircraft engines mandate some engine care considerations that we don't need to employ for our cars.

Regarding dehydrators, I opted for simplicity and a high volume of silica gel. I only measure the humidity in the silica chamber, which typically runs 10% - 12%.

I empirically trust the process, but won't know the real value for at least another 1500 tach hours. Hopefully not less.

[Snowflake]

Another step to consider in amongst all the other options, is opening the oil door and opening the dipstick after shutdown. If you unscrew your dipstick and just pull it out far enough to set the head off to one side and leave the tube open, you can watch a LOT of steam escape the chamber while it's still hot. It's a good way to remove a bunch of the moisture from the engine while it's still in vapour form.

[sjhurlbut]

Originally Posted by SwimmingDragonfly96

Due to weather and travel, I don’t think I’ll be able to fly my new to me 7a for about 3 weeks total (one week in now).

Ohhhh my young Yedi California resident. First world problems. Try Moose Jaw, Sask in March!!!!

Its fine but don't ground run it. Oil needs to get up to temp to do any good otherwise you're just creating more moisture.

[A1AVIATON47]

SUMP FUEL TANKS ....