Overhauled Lycoming O-300, High Metals/Lead on Last Sample

Joined
Oct 6, 2009
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12
Location
Sharon, SC
Words from Blackstone from last sample: "cylinder-area metals have increased quite a bit. We expect high metals during wear-in, but things should generally improve -- these increases could show a problem with pistons, rings, and/or cylinders. It's possible the increases are due to running rich, but we can't say for sure if that's the case or not. Test compressions, borescope, and check back."

Any speculation past their write up?

Code:
OIL XC20W-50 XC20W-50 XC20W-50
HOURS IN USE 14 27 33
HOURS 14 41 74
SAMPLE TAKEN 6/12/20 7/17/20 1/15/21

ALUMINUM 10 5 31
CHROMIUM 11 12 30
IRON 45 63 168
COPPER 19 19 20
LEAD 1286 2504 3095
TIN 4 3 3
MOLYBDENUM 2 0 0
NICKEL 2 2 3
MANGANESE 3 1 3
SILVER 0 0 0
TITANIUM 0 0 0
POTASSIUM 1 1 1
BORON 2 0 1
SILICON 22 15 17
SODIUM 6 4 6
CALCIUM 6 2 1
MAGNESIUM 11 7 13
PHOSPHORUS 3 0 0
ZINC 19 10 15
BARIUM 0 0 0

INSOLUBLES 0.2  WATER 0 0 0
FLASHPOINT °F 85 480 450
SUS VIS 210 °F 4.3 94.8 89.6
cSt @ 100 °C 19.4 19.14 17.89
 
The metals certainly seemed take a quite a jump . The viscosity is lower. There are some Aircraft people on board that can give some great advice . Usually I'll post Aircraft is a Latin word for expensive.
 
Last edited:
Have your A&P do as they say and do a short interval on the next run. The flashpoint and hot viscosity numbers on the first sample are odd....must be a mistake.

The lead number is high, but accumulates with hours. Any changes in flying patterns between the samples; less leaning maybe, touch and goes??

Didn't know Lycoming made an O-300. What airplane?
 
O-300 sounds like a Continental, like the small 140 HP 6 cyl that powered the early Cessna 172s.

When the engine break-in is "done", you'll know because oil consumption will drop. My engine burned 2 quarts in the first 2 hour flight, then after that it burned 1 quart every 15-20 hours. If oil consumption doesn't stabilize then the cylinders may be glazed.

When I put a new Lycoming O-360 in my 172, I didn't do UOA during break-in cuz I knew metals would be all over the place. I started with the 3rd oil change at 60 hours. You can see it started with high Al and Cr, like many engines do when new. But it took nearly 400 hours for it to start to come down to normal. That's longer than usual.

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