Chrome cylinders

[Owen M20F]

Hey everyone, so i just bought a 67 M20F and it got new chrome cylinders about 30 hours ago. I’m still experiencing very high CHT, shouldn’t the temps have come down by now? Thanks

[cctsurf]

Are you sure the fault is the cylinders?  I've seen much on here about baffle installation.  If, when the cylinders were installed, the baffles were not correctly installed, that may be causing your high CHTs.  It's not just a screw on affair...there are tolerances required.

I was able to lower chts on my plane by doing work on sealing the baffles...  it's amazing what a few small holes cause.

As to the Cylinders:

New or rebuilt?  Not that it matters a bunch, but chrome cylinders tend to be run out cylinders that can be plated for one more go-round.

Depends how often and hard it has been flown.  Chrome is hard, and takes some time and hard flying to wear in.  I forget the parameters, but in my knowledge of newly rebuilt engines (new cylinders), the mechanic said to take off full throttle and fly full throttle for a couple of hours to put the most pressure on the cylinder walls.  I've also seen engines which had sat for some time required essentially a new break-in.

 

[M20F-1968]

I have a 1968 F with chrome cylinders.  They should not affect temperatures at all.  They are very difficult to break in however.  Run the airplane like you stole it.  I used Phillips X-country 20/50 for break in and still use it.  Oil usage will probably be higher than other cylinders.  The good thing is they will not rust.  

It may take 100 hours or more to break them in.  

John Breda

[Owen M20F]

  On 10/14/2020 at 6:27 PM, M20F-1968 said:

I have a 1968 F with chrome cylinders.  They should not affect temperatures at all.  They are very difficult to break in however.  Run the airplane like you stole it.  I used Phillips X-country 20/50 for break in and still use it.  Oil usage will probably be higher than other cylinders.  The good thing is they will not rust.  

It may take 100 hours or more to break them in.  

John Breda

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This is what i wanted to hear! I think the temps are high because the new cylinders, I’m going to do an oil change and run some mineral oil to see if it helps break them in better

[carusoam]

Proper break-in is important...

Especially for chrome cylinders...

The objective is... to not leave a step in the wear pattern.

Steps occur from not varying the rpm at high MPs... typical of cruise flight...

If/When a step occurs... The rings drag across it on high power settings... like T/O.

having a chrome step in the cylinder wall, can act like a cutting tool, trimming off your rings at an accelerated pace...

If you can, see what the break-in procedure was for the existing set-up...

If you have a JPI... review the historical info to see what it has been doing...

PP thoughts only, not a mechanic...
 

Best regards,

-a-

[Ragsf15e]

  On 10/14/2020 at 7:56 PM, Owen M20F said:

This is what i wanted to hear! I think the temps are high because the new cylinders, I’m going to do an oil change and run some mineral oil to see if it helps break them in better

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I have chrome cylinders as well and generally agree with what John said above.  Mine did run hotter during break in but maybe only 10 degrees or so.  How hot are your cylinders running?

 I did my first 15-20 hours on mineral oil, then xc20-50.  In the end they are ok but definitely use more oil.  Also, as mine aged (15 years and 1000 hours), the chrome started to corrode and flake off the cylinder walls.  Essentially I had to overhaul the cylinders to redo the barrels.  So maybe they don’t rust but the chrome can flake off.

[kortopates]

See https://www.aopa.org/news-and-media/all-news/2019/january/pilot/savvy-maintenance-breaking-good

Sure they're really Chrome? Chrome fell from popularity a long time ago, the much more popular plating is Cerminil or a.k.a. Nickel.  Although Chrome plating is still available, they are very hard to break-in whereas Nickel, which accomplishes the same corrosion proofing is even easier to break-in than steal cylinders. As mentioned, Chrome cylinders have a gotten a bad wrap from the plating flaking off the barrel which is not repairable. 

 

[Owen M20F]

  On 10/14/2020 at 10:03 PM, Ragsf15e said:

I have chrome cylinders as well and generally agree with what John said above.  Mine did run hotter during break in but maybe only 10 degrees or so.  How hot are your cylinders running?

 I did my first 15-20 hours on mineral oil, then xc20-50.  In the end they are ok but definitely use more oil.  Also, as mine aged (15 years and 1000 hours), the chrome started to corrode and flake off the cylinder walls.  Essentially I had to overhaul the cylinders to redo the barrels.  So maybe they don’t rust but the chrome can flake off.

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Yesterday when i flew i was on climb out and my cht peaked at 455. I think i can attribute that to it being 100 degrees outside. I also was having to leave the gear down for the short trip since i need gear adjusting so i did the flight with the gear down. When i saw it peak at 450 i turned the boost pump on and throttled back and it dropped

[Owen M20F]

  On 10/14/2020 at 10:13 PM, kortopates said:

See https://www.aopa.org/news-and-media/all-news/2019/january/pilot/savvy-maintenance-breaking-good

Sure they're really Chrome? Chrome fell from popularity a long time ago, the much more popular plating is Cerminil or a.k.a. Nickel.  Although Chrome plating is still available, they are very hard to break-in whereas Nickel, which accomplishes the same corrosion proofing is even easier to break-in than steal cylinders. As mentioned, Chrome cylinders have a gotten a bad wrap from the plating flaking off the barrel which is not repairable. 

 

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I’ll make sure but i think it is

[Ragsf15e]

  On 10/15/2020 at 3:47 AM, Owen M20F said:

I’ll make sure but i think it is

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It’s pretty easy to tell, there should be orange paint around the cylinder.

[Ragsf15e]

  On 10/15/2020 at 3:46 AM, Owen M20F said:

Yesterday when i flew i was on climb out and my cht peaked at 455. I think i can attribute that to it being 100 degrees outside. I also was having to leave the gear down for the short trip since i need gear adjusting so i did the flight with the gear down. When i saw it peak at 450 i turned the boost pump on and throttled back and it dropped

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Yeah, ok, that’s real hot.  You don’t want to run it that hot.  Gear down probably didn’t help as you were staying under 120mph.  You should be flying full rich, full power, fast, at ~5,000’ ish.  75% power for a while, then 65-75% iaw the lycoming guidance.

If it gets that hot under those conditions, something else might be wrong... baffling, or fuel flow?

[M20F]

  On 10/15/2020 at 3:46 AM, Owen M20F said:

Yesterday when i flew i was on climb out and my cht peaked at 455. I think i can attribute that to it being 100 degrees outside. I also was having to leave the gear down for the short trip since i need gear adjusting so i did the flight with the gear down. When i saw it peak at 450 i turned the boost pump on and throttled back and it dropped

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A lot of power to stay level with gear down, 120 mph IAS, etc.  I would say your temps are about right, given the circumstances.  
 

What are your CHT’s under normal operation?

[EricJ]

  On 10/15/2020 at 5:31 PM, Ragsf15e said:

It’s pretty easy to tell, there should be orange paint around the cylinder.

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The cylinder paint code on I/O-360s is usually on the top fins between the pushrod tubes, or on a band around the base of the barrel.   Blue is nitrided, orange is chrome, nothing/grey is basic steel.

https://www.lycoming.com/content/understanding-engine-color-codes

Like this, which is mine, which the blue indicates has nitrided cylinders:

 

[Owen M20F]

  On 10/15/2020 at 5:31 PM, Ragsf15e said:

It’s pretty easy to tell, there should be orange paint around the cylinder.

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I’ll check tomorrow!

[Prior owner]

An IA recently told me that chrome cylinders may also be painted other colors, such as red, which would indicate the type of chrome (Ceramichrome, etc..), but he could find no reference for this.  
 

Lycoming’s current info online regarding the subject:

https://www.lycoming.com/content/understanding-engine-color-codes

I am wondering whether anyone has ever heard of the practice of painting cylinders colors other than the standard band colors...

According to my engine log, the engine engine overhaul shop that performed my overhaul Installed “chrome” cylinders, which I verified by borescope inspection, however, the painted bands are clearly red, and not orange.

Perhaps they ran out of orange paint that day?

Edited October 17, 2020 by PilotCoyote

[Guest]

A blue stripe normally means nitrite hardened cylinder walls, plain gray means plain steel cylinder walls, orange band means channel chrome cylinder walls, 2 orange bands with gray between means ceramic-Chrome, green strip means 0.010” oversized bore, yellow strip means 0.020” oversized bore.  Yellow above the spark plug means long reach spark plugs, gray means standard length spark plugs.

Clarence