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

Messages
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            <0.6         0.4
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
 
Messages
2,774
Location
Caldwell Idaho
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:
Messages
1,951
Location
New England, USA
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?
 
Messages
832
Location
98245
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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