Plugs

[Brad Brady]

Guess which plugs came from the left Bank .....Brad

[1SeventyZ]

Ewww....

Humor me-- -Why the radical difference in combustion between left side to right? Issues with your intake left side?

[Brad Brady]

Ewww....

Humor me-- -Why the radical difference in combustion between left side to right? Issues with your intake left side?

This is normal in all C-145's and O-300's.....I've known about this for thirty years.....I just haven't seen it this pronounced before, I lean agelessly.....but I leased this aircraft back, for the last 40 HRS. To a local flight instructing airport. I'm sure they don't use my.....maybe not so FAA approved, ideas of checking carb heat....I check on base, then turn off... If I think I need more...then I check as necessary. I thought this picture was worth a thousand words.It has been known that the left bank burns richer.....But why? Can it have a reason because of prop wash?...Maybe down wash making pressure and up wash making draft? or visa-verse? I have no idea...I'm sure there is an engineer out there that can answer this question..... But your guess is as good as mine.....Brad

[jrenwick]

I've never seen anything like this on my O-300s. Is the intake air baffle inside the oil pan in good shape? Are the mags wired correctly, left mag to all the bottom plugs, and right mag to the top ones? (I had to fix the wiring on my 170, because somebody had "helpfully" split each mag between top plugs on one side and bottom on the other.)

[Brad Brady]

I've never seen anything like this on my O-300s. Is the intake air baffle inside the oil pan in good shape? Are the mags wired correctly, left mag to all the bottom plugs, and right mag to the top ones? (I had to fix the wiring on my 170, because somebody had "helpfully" split each mag between top plugs on one side and bottom on the other.)

John,
Everything is in order.....I have seen this before.... but only when burning mo-gas.....this is 100LL with TCP.....Go figure.........Brad

[GAHorn]

It is the sfister valve, of course! Don't forget to check the ball bearings...everything's ball bearings these days

[blueldr]

Left bank is running rich. Check for leaking primer system.

[Drat]

Looks like a vac leak to me.

[1SeventyZ]

This is normal in all C-145's and O-300's.....

I have to disagree. My plugs all look the same -- A nice dry mocha color.

[Robert Eilers]

As previously indicated earlier on in the posts, my experience with the C145/O-300 is that leaning technique matters a bunch.

[GAHorn]

I've never heard of the C145/O300 having an endemic problem such as this, and can only suggest it's not. The left mag fires the lower plugs 2-degrees prior to the right mag firing the upper plugs to alleviate a lower-plug-fouling problem typical of all horizontally-opposed engines, but that is the only consistent pattern of fouling I've ever heard of, and even that is usually traced to worn valve-guides.

[Brad Brady]

I've never heard of the C145/O300 having an endemic problem such as this, and can only suggest it's not. The left mag fires the lower plugs 2-degrees prior to the right mag firing the upper plugs to alleviate a lower-plug-fouling problem typical of all horizontally-opposed engines, but that is the only consistent pattern of fouling I've ever heard of, and even that is usually traced to worn valve-guides.

George,
I think your on to something here....I leased the aircraft to a local flight instruction airport in the spring and early summer, so I thought I would service the engine with Aeroshell 15W-50 so they wouldn't have to worry about making an "oil cocktail" with the changing temps. with the straight weight oils I usually use. I'll bet that the guides are getting worn and the 15-50 is passing by more readily than the straight weight AD oil would. I've always seen this ......just not this pronounced.....Brad