Mismatched Cylinders

[jkhirsch]

I apparently now have one side of my engine running two nitrided cylinders and the other side running two steel cylinders. All four of the cylinders are the "original" cylinders from the overhaul just had to put oil control rings in two of them and they have come back nitrided. The last set of two sets of compressions were 78 on the steel ones.

 

Does this constitute a problem in anyones mind?

[jetdriven]

Factory cylinders are nitrited. However the overhaul shops bore this out and although they claim to re-nitirde them, it is not as good as the factory process. Same with lifters.

[Shadrach]

They're not mismatched... They're all steel. What color are the color code areas on the cylinders?

[mike_elliott]

shouldn't make a bit of difference, They are the same bore, Compression ratio, thus should pump the same amount of exploding air thru them and make equal power, assuming everything else functions as they should (rings etc)

[jkhirsch]

From what I can see, the two reworked cylinders are coded with the blue "nitride" code and the two that haven't been touched do not have any color code on them. The "un-worked" two are from an original overhaul in 2003, would they have been factory nitrided and not color coded, or are they simply steel barrels. I do understand that the cylinders are physically composed of the same material.

[Shadrach]

I beleive that they would be "through hardened" if "grey" or absent a color code, blue as you know means they are nitrided. It makes no difference anyway, If they're all healthy, then everything should run nice and smooth!

[jkhirsch]

it's reassuring to hear from someone else that common sense basically prevails, 'what the hell's the difference what coating is on the cylinder if it's working correctly.' (short of I have heard that chrome causes a lot of problems) i have zero confidence that i'm not going to end up having both of the "un-worked" cylinders fixed for the same reason that the first two were done, but I err toward the side of fix it when it's broken.

[garysuperpilot]

My 67 m20F, the one you looked at a while back has the same thing ; two with the blue band and two without. Apparently they were reused at the major. My mechanic noted it but said it really didn't matter as long as they were all performing well. No worries.

[Shadrach]

it's reassuring to hear from someone else that common sense basically prevails, 'what the hell's the difference what coating is on the cylinder if it's working correctly.' (short of I have heard that chrome causes a lot of problems) i have zero confidence that i'm not going to end up having both of the "un-worked" cylinders fixed for the same reason that the first two were done, but I err toward the side of fix it when it's broken.

Why were the first two oh'd?

[jkhirsch]

Broken oil control ring in both.

[kellym]

My 67 m20F, the one you looked at a while back has the same thing ; two with the blue band and two without. Apparently they were reused at the major. My mechanic noted it but said it really didn't matter as long as they were all performing well. No worries.

 

On the 200 hp Lycoming engines all cylinders come from the factory with nitriding. Don't know whether they all get color coded. Only if a cylinder is bored more than 0.10 oversize will that nitride layer get penetrated. While you can get overhauled cylidners with Cerminil treatment, there are no PMA aftermarket cylinders for the 200 hp engine. Both ECI and Superior have promised PMA angle valve cylinder, but none have come through so far.

[Marauder]

My 67 m20F, the one you looked at a while back has the same thing ; two with the blue band and two without. Apparently they were reused at the major. My mechanic noted it but said it really didn't matter as long as they were all performing well. No worries. On the 200 hp Lycoming engines all cylinders come from the factory with nitriding. Don't know whether they all get color coded. Only if a cylinder is bored more than 0.10 oversize will that nitride layer get penetrated. While you can get overhauled cylidners with Cerminil treatment, there are no PMA aftermarket cylinders for the 200 hp engine. Both ECI and Superior have promised PMA angle valve cylinder, but none have come through so far.

My last overhaul had Lycoming cylinders with nitriding. Gray cylinders with an orange stripe.

[jetdriven]

Orange stripe denotes chrome cylinders. The factory doesn't make them that way.

[Marauder]

Orange stripe denotes chrome cylinders. The factory doesn't make them that way.

 

Now you are going to make me go look. I may be remembering my last engine that did have chrome cylinders. Blue? I remember orange and blue... I do remember that my last engine was a Lycoming reman.

[jetdriven]

Blue stripe or cylinder base is steel nitrided cylinders. Orange is channel chrome. I saw a new one the other day, a gray cylinder with a silver stripe.  Cerminil? Nickel Carbide? Nickel?  Those guys are always offering new exotic cylinder finishes every couple years. I wonder why they keep changing them....

[Seth]

Some engines have different manufacturers cylinders mismatched - as noted if the compression, bore, and all that stuff is the same, the engine doesn't know the differnce.  Many aircraft when a jug or two need replacing do not match the cylinder.  They go with either the cheapest, the best available, the newest technology and such.  Some owners try to match for resale value so that the logbooks and engine look unform.  I looked at an airplane for sale about six years ago and the cylinder cooling fins were slightly different, fond out it was because ti was different cylinder manufacturers. Engine purred very smoothly too.

 

My aircraft, and my former aircrat, all had uniform cylinders.

 

-Seth