Zero hours/sitting idle

Half Fast said:
I’ll note that CamGuard in oil works almost as well as pickling and allows the plane to be flown.
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Just to add, the CamGuard only helps within the 30 day window of inactivity most OEMs use as a benchmark for when to preserve an engine. Beyond that 30 days CamGuard does not give you the protection a MIL-SPEC preservation oil or additive will. Unfortunately, have known several individuals who believed CamGuard was equal to a preservation oil much to their detriment.
Ed Haywood said:
the presumption should be that corrosion has started on the camshaft, ground run or not.
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FYI: if the engine had been overhauled and not flown for at least 50 hours you can probably bet the bank the cylinder walls/rings had become rather rusted to the point of causing an issue after 2 years. The cam wouldn't even be a concern at that point.
 
iamtheari said:
I’m willing to bet there isn’t any corrosion at all.
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Only if the airplane does not exist.

My experience as a mechanic, dealing with owners who have ground-run their engines, tells me that ground-running is a killer. Even Lycoming and Continental tell you that, and Ram Aviation has a video on engine corrosion and they mention ground-running as quite undesireable. In removing rocker box covers on engine that have been ground-run for maybe ten minutes, I have found water in that cover. If I pull a cylinder, I find water droplets in the cylinder and on the pistons skirt, and corrosion pits in the cylinder.

Wishful thinking does not trump real-life experience.
 
SoonerAviator said:
Seems like a lot of presumptions for not having seen the aircraft. Maybe it was run on the ground 2 or 3 times in that period, who knows. Could be a heck of a deal. Pay a mechanic to do an hour inspection for any engine corrosion/deal-breakers without going through a whole pre-buy. Might be a chance to pick up a zero-time aircraft without major headaches. Don't know until you see it.
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An hour isn't going to do the job. At the very least, a magneto needs to come off to get a look at the steel gearing and mag drive. Moisture in the case will leave rust on them, and if they're rusted, likely the cam and lifters and cylinder are, too.
 
Dan Thomas said:
An hour isn't going to do the job. At the very least, a magneto needs to come off to get a look at the steel gearing and mag drive. Moisture in the case will leave rust on them, and if they're rusted, likely the cam and lifters and cylinder are, too.
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Sorry, wasn't clear in my comment, I just meant an hourly rate just to do the inspection on the engine for corrosion. Not a full prebuy or evaluating every last accessory/inspection port. Enough to run a borescope and see if any significant corrosion exists. My only point is that there are some assumptions being made that the engine is already toast because the guy did some ground runs. Without knowing some additional details about frequency/duration of those runs, or what additional steps may have been used (CamGuard, etc) I think it's silly to automatically "walk away".
 
Bell206 said:
However, some still couldn't get their mind wrapped around running an engine creates moisture from a hot combustion process.
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C8H18 + 12.5 O2 → 8 CO2 + 9 H2O

Somewhere, a high school chemistry teacher is shedding a tear.
 
SoonerAviator said:
Enough to run a borescope and see if any significant corrosion exists.
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Just try borescoping the case on a Lyc to get a look at the cam and lifters. Nope. Cylinder has to come off. There's no access. On some of the 540s, those that have the oil filler up top, there might be a chance through that filler. Never tried it. Even though the bottom of the oil sump you have to deal with the narrow slots in the case above the sump and below the crank.
SoonerAviator said:
I think it's silly to automatically "walk away".
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Your money, not mine. My experience tells me that it's a huge risk. What's your experience with this?
asicer said:
C8H18 + 12.5 O2 → 8 CO2 + 9 H2O
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A gallon of gasoline can create a gallon and a half of water. Most of that goes out the exhaust, but in an engine that isn't at operating temperature, the ring gaps are still large and considerable stuff gets past them and into the case. Not just water. either; there are other corrosive combustion byproducts as well. The water is bad enough; it mixes with the oil, and in the presence of metals to act as catalysts, acids are formed over time after shutdown. Hydrochloric, sulfuric and nitric acids that eat that engine.

1716950124456.png
From https://www.lycoming.com/content/low-time-engine-may-not-mean-quality-and-value

1716950184855.png

From https://www.lycoming.com/content/frequency-flight-and-its-affect-engine
 
I learned something today in math class. That the recommended min oil temp of a Lycoming engine, above, is identical to the ideal sous vide temp for dark meat chicken, 165F. Coincidence? I wonder.
 
TommyG said:
Got it in 1990 something, still using my AOL email. If compuserve still existed, I would use that.
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Compuserve email still works. I have mine. I use it where I suspect I might get spammed.

You could even access it using your old CIS number until not that long ago.

FYI, AOL bought Compuserve, so my CIS email is run by AOL. :D
 
AOL is owned by Yahoo! which is owed my a large conglomerate.
 
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