O-470 Cylinder broke in yet? Borescope images included.

[robertb]

Hello all,
My mechanic installed an overhauled cylinder during the annual last month. I've been flying it like the Continental manual says and expected the cylinder to be smoother after 12 hours of hard flying. Before everyone had a borescope, we could "just kinda tell" based on oil consumption, right? The plane does not have an engine monitor installed. So, I'd like to hear your thoughts on how the break in progress is going based on the attached photos. For what its worth, the engine has burned one quart in the 12 hours since the cylinder was installed. Typically, the plane burns a quart every 15 to 18 hours.

 

[Dan Thomas]

Crosshatch will hang around for a very long time. It's part of what keeps the rings lubricated. The scoring, on the other hand, is concerning. Someone wasn't very fussy about keeping things really clean when changing that cylinder.

 

[bonefishpete]

I'd die for a 1 in 12 oil burn on a 0-470.

 

[geezer]

Friends turbo 4 cylinder blew a head gasket at 40,000 miles. Cross hatch was still very much there on all cylinders.

 

[Stewartb]

Crosshatch will hang around for a very long time. It's part of what keeps the rings lubricated. The scoring, on the other hand, is concerning. Someone wasn't very fussy about keeping things really clean when changing that cylinder.

Loose carbon from the piston? That’s my guess. Probably looks worse than it is. If it ain’t broke, don’t fix it.

 

[Gary Ward]

The honing pattern was still visible on a 1900 hour lycoming when I had it apart.

 

[robertb]

Great data points folks! I appreciate it. The jug which was pulled had 1,600 hours on it and was pretty nicely polished on the inside of the barrel. I am thinking I can run it like I used to and not do the high-power and change rpm every 15 minutes routine now.

 

[Domenick]

I agree. Time to fly it like you own it.

It doesn't really look like wrist pin scoring, but where is the scoring in relation to the wrist pin?

 

[robertb]

It doesn't really look like wrist pin scoring, but where is the scoring in relation to the wrist pin?

With the borescope I have (Teslong TD450S), I need to act like a one of those bendy people at the circus to see all the way around the cylinder. But if memory serves me roughly correct, it would have likely been at the 3 or 9 o'clock position (near the wrist pin locations).

 

[Rcmutz]

1qrt in 12 hours is great! Honing looks good. If it were smooth, I’d be concerned. Also, check the oil filter after 25 hrs and make sure you are not seeing any metallic “sand” in the pleats. I had a piston pin cap rubbing on a cylinder wall on my previous 0-320. Took removing the 4th cylinder to find it. This was before the advent of the inexpensive boroscope!

 

[robertb]

1qrt in 12 hours is great! Honing looks good. If it were smooth, I’d be concerned. Also, check the oil filter after 25 hrs and make sure you are not seeing any metallic “sand” in the pleats. I had a piston pin cap rubbing on a cylinder wall on my previous 0-320. Took removing the 4th cylinder to find it. This was before the advent of the inexpensive boroscope!

Understood. I am running Phillips 20w50 X/C now for the initial break-in. It will be changed it in another 10-15 hours or so. I usually run Phillips Victory 100AW.