Oil Analysis- C150M - O-200

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Alessandro

Filing Flight Plan
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Mendicanted’aria
Total time SMOH 970 (15 years ago) Total on 4 cylinders 360 (8 years ago).

Good afternoon all,

Recently bought a C150 to fly around for fun. I love it but since it was only flying 20 to 40 hours a year for the last 10 years I decided to do an early oil change (11.5 hours). I logged these in the last 12 days. I decided not to remove the screen as I had little hours on it. Sent a sample out to test. Here are the results….

Alluminum - 8ppm
Iron - 62.73 (Flagged as Caution)
Copper - 8.08
Nickel - 1
Chromium - 1
Silver- <1
Silicon- 8

Am I screwed? I really don’t want a to do a MOH yet.
 
Type of Starter?

The Clutch can be a source of iron or copper.

Even if was replaced 100 hrs ago.
 
What's people's opinions of pulling the oil screen and fitting a proper oil filter. It's the first think I would do.
 
Bathman said:
What's people's opinions of pulling the oil screen and fitting a proper oil filter. It's the first think I would do.
Click to expand...
I already bought the converter piece to mount an oil filter instead of the screen.
 
As mentioned iron shows up in engines that have been sitting. It should decrease as the aircraft is flown more often.
 
You said you’ve flown for some time, but haven’t inspected the screen. Do it.

If ok, fly it with the new filter, 10, 15 hours, then pull & cut the filter for inspection.

Worst-case is cam/lifter corrosion leading to erosion.

Lots of A&P experts (not me) here that could weigh-in, but also good if you can find a local expert to put fingers and eyes on it and to bounce 5 senses and brain off of...
 
Alessandro said:
Am I screwed? I really don’t want a to do a MOH yet.
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FYI: oil analysis is more trend monitoring than a simple one time test. Plus there are a number of variables that can influence those results such as how/where you took the oil sample, etc. I'd talk to your APIA about this and read up on oil monitoring before making any drastic moves.
 
I agree with Bell’s comments. Another variable is how the sample was taken.

WHY didn’t you pull the Screen? Easy on O-200. I also run my finger around the bottom of the cavity and often find particles of carbon or metal there.

The welded seam across the bottom of the Sump is prone to collecting and holding particles; for a while. Later they show up in the Screen /Filter. I encountered this on a O-200 that had a copper “ mist” oil Rocker Covers as well. After a lot of cleaning and searching we found some particles in the now removed Sump. Records showed the Clutch had been replaced several hundred hours earlier. Talked to Niagara Clutch folks and they affirmed it could have come from the key- start type Clutch. However; they could not tell if the issue had come from the core due to time. Why is took 200 hrs to show up is a mystery.

Adjustment and operation of the pull type Clutch is critical. Engaging the gears with the Starter or Engine turning will grind the gears. When examining removed parts the Clutch Gear can look ugly. This would put ferrous particles in the oil.

Removal of the Sump is something to consider if you believe there is an issue.
Not a 10 minute task though. Draining your oil through a paint strainer may provide an indication. Flushing the Sump with a solvent can clean out residue when doing this. Removing the quick-drain will provide better drainage. Dry and inspect before adding oil.
 
Iron in the oil analysis can come from ground-running the engine without flying it. That puts far more water into the engine than any environmental moisture can (unless the airplane is immersed!). The engine needs to be flown to get temperatures up to where that moisture is driven off and out the breather. Otherwise it sits in the engine and starts the corrosion process. Aircooled engines have large cold clearances that let considerable combustion gases past the rings when the engine isn't at operating temps. These aren't modern car engines.

A gallon of gasoline can generate more than a gallon of water. You see it blowing out of car tailpipes on cold days. On really cold days you can see it coming out of aircraft exhausts too.
 
As Bell206 mentioned, oil analysis is best used to detect changes or trends, by doing it repeatedly.

Oil analysis is a great thing, but one incident by itself is not a basis for starting an overhaul.

Metal in your filter or screen could indicate an overhaul is needed, even with just one incident if the metal is a lot, for example more than 1/2 teaspoon as per Lycoming Service Bulletin 480F.

Without a lot of metal in the filter, I would continue flying, and taking oil samples regularly. You’ll probably fly more often than the previous owner, and if all is well you’ll see the oil analysis gradually improve as you have less corrosion from inactivity.
 
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A gallon of gasoline can generate more than a gallon of water. You see it blowing out of car tailpipes on cold days. On really cold days you can see it coming out of aircraft exhausts too.[/QUOTE]

I would research this statement a bit unless the laws of physics have changed since my college days.
 
My rough estimate is about 1.4 gallons of water, but I wasn't a ChemE. Probably more important is the dew point of exhaust combustion gasses is about 180 degF.
 
Jeff767 said:
A gallon of gasoline can generate more than a gallon of water. You see it blowing out of car tailpipes on cold days. On really cold days you can see it coming out of aircraft exhausts too.
Click to expand...

I would research this statement a bit unless the laws of physics have changed since my college days.[/QUOTE]
Gasoline is a mix of a bunch of hydrocarbons, but for the sake of simplifying the math, lettuce assume that it is C8H18 (Octane).

25(O2) + 2(C8H18) =18(H2O) + 16(CO2)

So you get more water + CO2 coming out than you had gasoline going into an engine.
 
Jeff767 said:
I would research this statement a bit unless the laws of physics have changed since my college days.
Click to expand...
I did, last year when we were having a similar discussion.

Have you ever pulled the cylinder off an engine that had been sitting all night and then run for ten minutes before inspection? I have. Water in that cylinder, between the piston and cylinder. Water in the case. Water in the rocker box. It caused corrosion in the cylinder that shaved bits of aluminum off the piston pin plugs, showing up in the filter and triggering the cylinder removal. O-235, famous for running too cool. Flight school airplane, flying every day, hangared every night.

Did that more than once, too.
 
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