Attention: Tom! IO-540 #5 Cylinder Low Plug Oil Soaked

[Geico266]

Tom, or anyone,

Like the title says I have an IO-540 that is in annual. The #5 cylinder has the lower plug oil soaked when I pulled the plugs out. Last year is was the same thing. Oil consumption is about 1 QT per 8-10 hours.

The engine runs like a top and mag drop is normal, so I know the plug is firing when the engine gets warmed up. It is not sooted up, or heavy black, just wet with oil.

Any ideas on what it is and should I mess with fixing it or just fly it?

Thanks in advance for any comments.

 

[Tom-D]

Tom, or anyone,

Like the title says I have an IO-540 that is in annual. The #5 cylinder has the lower plug oil soaked when I pulled the plugs out. Last year is was the same thing. Oil consumption is about 1 QT per 8-10 hours.

The engine runs like a top and mag drop is normal, so I know the plug is firing when the engine gets warmed up. It is not sooted up, or heavy black, just wet with oil.

Any ideas on what it is and should I mess with fixing it or just fly it?

Thanks in advance for any comments.

If that is the only symptom you have I'd leave it alone.

BUT

IF you must do something, pull the cylinder off far enough to change the oil control ring and put the cylinder back on.

 

[Geico266]

If that is the only symptom you have I'd leave it alone.

BUT

IF you must do something, pull the cylinder off far enough to change the oil control ring and put the cylinder back on.

That is good news! I'm picking the first option!

She runs strong, never a hickup, mag check is fine.

 

[Tom-D]

That is good news! I'm picking the first option!

She runs strong, never a hickup, mag check is fine.

What is happening is, the oil control ring is leaving a little too much oil behind on its down stroke, which is collecting in the compression rings and after shut down, the oil creeps out into the combustion chamber and ends up in the lower plug.

during normal run the oil is burned and nothing is noticed.

 

[Geico266]

What is happening is, the oil control ring is leaving a little too much oil behind on its down stroke, which is collecting in the compression rings and after shut down, the oil creeps out into the combustion chamber and ends up in the lower plug.

during normal run the oil is burned and nothing is noticed.

The amount of gray material is just barely more than the other plugs that are dry.


Thanks Tom, you made my day.


What are the symptoms of leaking valve stem guilds?

 

[Tom-D]

The amount of gray material is just barely more than the other plugs that are dry.


Thanks Tom, you made my day.


What are the symptoms of leaking valve stem guilds?

YAVW.

 

[Geico266]

Tom, what are the symptoms of a leaking valve guild?

 

[dell30rb]

Oil consumption. Generally with leaky valves, If you let it idle for a minute or so, then give it some throttle, you'll get a puff of smoke that quickly goes away

 

[Tom-D]

Tom, what are the symptoms of a leaking valve guild?

Valve guides do not leak, their purpose is to hold the valve in a position to seat on the valve seat, when they wear out the valve will not longer contact the seat in a position that it will seal the cylinder.

Lycomings valve wobble check IAW their S/B is to check for this wear.

 

[Tom-D]

Oil consumption. Generally with leaky valves, If you let it idle for a minute or so, then give it some throttle, you'll get a puff of smoke that quickly goes away

Leaking valve usually means there is a leak between the valve and the valve seat. not the oil that will leak from the valve spring/rocker shaft area into the exhaust or intake passage way.

Any oil that leaks thru the guide will either be taken into the cylinder on the next intake stroke and burned, or ported out the exhaust pipe. This leakage will cause high oil usage. ut when it is bad enough to show smoke you will have other symptoms like low compression on the compression check, because the valves will not be seating properly.