O-470 Piston Engine high chromium

[AlanCanada]

I purchased an aircraft with an O-470 Continental, 6 cylinder engine. I'm into the second oil analysis report with the analyst identifying higher than normal chromium in the sample. Should I be concerned? Report section attached. I run it about 50 hours between oil changes.

 

[wings&wheels]

That is a bit high...

How is compression?

 

[TheLoneRanger]

The iron and nickel are borderline high too. Might be a cam lobe wearing...? I'd do another test at 25 hours and see how it compares.
How many hours on the engine?
2000 hour TBO?

 

[vw7674]

AV web has a useful write up on 0-470s.
Upside is the -L, -R & -S series are 1,500 hour tbo.
The O-470-U is the 2,000 tbo but only when equipped with steel, not chrome-lined,barrels.

 

[ZeeOSix]

What oil has been used in that engine? What oil is specified?

 

[Cujet]

Hard to say why you have chrome in the oil. Do any of your cylinders have an orange paint mark on them? That's generally the indication it's a chrome lined cylinder.

Also, have you borescoped the cylinders for indications of internal problems? As mentioned above, compressions OK? Oil consumption OK?

If you have a chrome lined cylinder, that will produce modest chrome levels in the oil.

The thing with aircraft engines is that a single UOA result is generally not useful. Typically, only the trend is useful.


EDIT: 50 hour oil changes are, in my opinion, too long. I try for 25 hours and sometimes go 30.

 

[Linctex]

This is the first Piston Aircraft UOA I have seen on 100LL AvGas.

I'm awed at the lead numbers!

Switch from Aeroshell W100 to Aeroshell 15W-50 semi-synth and see if the numbers go down?

 

[AlanCanada]

Thank you everyone for the follow-up. Answers below

Cylinders are not chrome, they are steel
Lead numbers are not my concern as it is in tolerance. I am going to keep the same oil as the chromium is going down. I read an article that said that mineral oil removes more lead from the engine, that may explain why the lead number went up after the change
Engine has 130 flight hours since over haul, oil had about 52 hours on it
It's an R series with a 1600 Hr TBO

Additional Info
Previous owner overhauled the engine in 2016, he then had it for 2 years without an oil change, in fact, it looks like he had the break in oil for two years. He only flew 38 hours in 2 years. He changed the oil and then 7 months later sold the aircraft to me. He only flew 3 hours in those 7 months. My current theory is that I am cleaning out the engine as I have already operated about 100 hours this year so far.

 

[FastLane]

I also only run my oil for 25 hours. Oil is cheap. Engines are not. I would try some Phillips 20W50.

 

[AlanCanada]

Using that logic, why don't you change it after every flight?
Originally Posted by FastLane
I also only run my oil for 25 hours. Oil is cheap. Engines are not. I would try some Phillips 20W50.

 

[AlanCanada]

Update: These engines use two spark plugs on every cylinder fired by two independent magnetos. I have diagnosed that one of the magnetos was going bad and have removed it for an Inspect and Repair As Necessary (IRAN) also known as a 500 h inspection. I'm going to be interested to see if this was the root cause of the elevated chrome.

 

[Surestick]

Originally Posted by AlanCanada
Update: These engines use two spark plugs on every cylinder fired by two independent magnetos. I have diagnosed that one of the magnetos was going bad and have removed it for an Inspect and Repair As Necessary (IRAN) also known as a 500 h inspection. I'm going to be interested to see if this was the root cause of the elevated chrome.


Why would a bad mag increase chrome in the oil? From what I remember oil doesn't usually circulate through the mags?