OK fellow Pilot Lounge Lizards, I need your help. Ole Pokey is still in for her annual, but should be ready to fly sometime next week and she had to have a new exhaust valve & seat (new rings of course) in one cylinder. Tell me how to best break that cylinder in. Engine (Cont O-300 B) will have mineral oil in it replacing the usual Aeroshell 50w. My normal procedure would be to take off, get up to a comfortable altitude & run the heck out of it, watching the oil temp & cyl head temp to be sure they don't get too hot. I would run it that way for an hour or so or until the temps stabilize. Then I would run it pretty hard for several more hours over a period of several days to be sure the rings had seated.
What would you suggest that I do differently and why?
thanks,
Cylinder Break In Procedures
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
Cylinder Break In Procedures
OLE POKEY
170C
Director:
2012-2018
170C
Director:
2012-2018
Well Pokey, I'll tell you how I did it. Since I busted my "Real" airplane last year, I've had to fall back on my "spare". This pig of an airplane is a 55 B model that sat on the ramp at Chandler Field in Fresno for about 12 or 14 years unflown. You can understand that it was in great shape! The cylinders were pretty well clogged up with bird s--t and nest residue so I pulled them off and sent them to the local automotive machine shop for washing and bead blasting inside and out. Came out looking like new. Then I had the valves and seats done and deglazed the cylinder walls with a dingleberry hone. I installed ECI rings and gasket set on reassembly. This engine, a C-145 , was last overhauled in 1963, that's 41 years ago. I also had the prop tweaked back from a 56 to a 50 inch pitch.
After a thirty minutes around the pattern and a cowling off inspection, I headed for Johnson Creek airport at Yellow Pine, Idaho, from my home base at Jackson, CA. I did not use straight mineral oil, but started right out on Shell 100W and cruised at 2600 RPM for 4 hours on the first leg and 1+15 on the second leg.
Oil consumption was about one pint. The flight home a few days later was 1+10 and 4+05 and total oil cousumption for the whole trip was just under a quart.
So much for breaking cylinders in on straight mineral oil! The last time I did an overhaul on a C-145, I used straight mineral,oil and varried the power settings for 50 hours and the SOB never did get any better than five hours to the quart.
In your case I'd say bolt the cylinder on and just GO!
After a thirty minutes around the pattern and a cowling off inspection, I headed for Johnson Creek airport at Yellow Pine, Idaho, from my home base at Jackson, CA. I did not use straight mineral oil, but started right out on Shell 100W and cruised at 2600 RPM for 4 hours on the first leg and 1+15 on the second leg.
Oil consumption was about one pint. The flight home a few days later was 1+10 and 4+05 and total oil cousumption for the whole trip was just under a quart.
So much for breaking cylinders in on straight mineral oil! The last time I did an overhaul on a C-145, I used straight mineral,oil and varried the power settings for 50 hours and the SOB never did get any better than five hours to the quart.
In your case I'd say bolt the cylinder on and just GO!
BL
cylinder break in
Thanks for the suggestion. When I did a major overhaul in 99 I flew it hard for 45 minutes, my AI said "I think the rings are seated" & I ran it pretty hard for the next 25 hours on mineral oil & that engine has not used more than a couple of qts in 25 hrs with hard running a lot of the time until this one cylinder (#2) crapped out on me at annual. I probably would have used 100w, but my AI put straight mineral oil in, so I guess I will run it for 25 hrs then go back to my regular 50 wt Aeroshell
thanks again
thanks again
OLE POKEY
170C
Director:
2012-2018
170C
Director:
2012-2018
I've always been a proponent of mineral (non-AD oil) for cylinder break-in, but I must admit that the last engine I broke in new (steel) cylinders on had only 4 hours previously had a fresh oil change, so I left the AeroShell 100W in to break in 3 new cylinders. I flew the heck out of it for 5 hours with high power settings, at low altitude, did an oil change and went back to normal ops.
They broke in just fine, and oil consumption is pretty low ....about 1 qt every 15 hours. By the time it was ready to add a second qt, it was already time for another oil change anyway.
I think the trick is to not "baby" the throttle, keep high manifold pressures for several hours at first, which dictates low altitudes (where good cooling is available as well.) The MP keeps the rings loaded against the cyl. walls for good contact/break-in.
Chrome cylinders are a different deal, in my opinion. I'd only use mineral oil with fresh channel-chrome cylinders.
They broke in just fine, and oil consumption is pretty low ....about 1 qt every 15 hours. By the time it was ready to add a second qt, it was already time for another oil change anyway.
I think the trick is to not "baby" the throttle, keep high manifold pressures for several hours at first, which dictates low altitudes (where good cooling is available as well.) The MP keeps the rings loaded against the cyl. walls for good contact/break-in.
Chrome cylinders are a different deal, in my opinion. I'd only use mineral oil with fresh channel-chrome cylinders.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
-
zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
4 years ago, my overhauler recommended breaking it in using Phillips XC20-50. Since that was what I used anyway, I did so. I use maybe 1-1/2 quarts in between 35 hour oil/filter changes.
Ditto George's comments re: run hard at low altitude,full rich. Also, at least at first, avoid extended ground running--taxi fast, do the run-up enroute to the runway, and GO. You'll avoid hot-spots that way.
How many hours in those 5 years since overhaul, Pokey? Seems kinda soon to be replacing valves,IMHO.
Eric
Ditto George's comments re: run hard at low altitude,full rich. Also, at least at first, avoid extended ground running--taxi fast, do the run-up enroute to the runway, and GO. You'll avoid hot-spots that way.
How many hours in those 5 years since overhaul, Pokey? Seems kinda soon to be replacing valves,IMHO.
Eric
Cylinder Break In
Eric,
You are correct about the engine not having sufficient time on it to be replacing valves. I hate to admit it, but I really don't know (without my logs, which my AI has at the moment), but I think I am under 350 hours smoh. Engine began with new overhaul in Sept. '99 & I average a little over or under 100 hrs per year, depending a lot on where the 170 convention is and I missed flying it to Anchorage since we did a cruise & used the kerocent queens. I know this doesn't add up, but my AI mentioned 300+ when he called me with the news. I plan to get my logs when I pick up the plane and calculate the actual hours. Last yr @ annual #2 compression wasn't any good, but after staking the values it came up to a reasonable #, this time it first showed 30/80 & after trying the staking again it went even lower. Turns out, as I probably already said, that it had to have a new exhaust valve & seat. AI indicated he suspected the seat wasn't set in correctly when new and the cylinder repair shop (Sentry-FW) indicated as much. The other 5 are OK. These are ECI cylinders.
Thanks for your suggestion. I will be following my orginal thoughts which pretty much mirrors what George said except it already has the mineral oil in it so I'll likely run it around 25 hrs, then switch.
Frank
You are correct about the engine not having sufficient time on it to be replacing valves. I hate to admit it, but I really don't know (without my logs, which my AI has at the moment), but I think I am under 350 hours smoh. Engine began with new overhaul in Sept. '99 & I average a little over or under 100 hrs per year, depending a lot on where the 170 convention is and I missed flying it to Anchorage since we did a cruise & used the kerocent queens. I know this doesn't add up, but my AI mentioned 300+ when he called me with the news. I plan to get my logs when I pick up the plane and calculate the actual hours. Last yr @ annual #2 compression wasn't any good, but after staking the values it came up to a reasonable #, this time it first showed 30/80 & after trying the staking again it went even lower. Turns out, as I probably already said, that it had to have a new exhaust valve & seat. AI indicated he suspected the seat wasn't set in correctly when new and the cylinder repair shop (Sentry-FW) indicated as much. The other 5 are OK. These are ECI cylinders.
Thanks for your suggestion. I will be following my orginal thoughts which pretty much mirrors what George said except it already has the mineral oil in it so I'll likely run it around 25 hrs, then switch.
Frank
OLE POKEY
170C
Director:
2012-2018
170C
Director:
2012-2018
While researching for another member I ran across a TBO Advisor article regarding engine myths, where they stated:
Myth: Low oil consumption is good.
Reality: Consumption of less than a quart every 20 hours is
not a good sign, because the top piston rings are probably
starving for oil. Accelerated cylinder wear is likely to occur at
some point.
I thought that was interesting, but even more curious was my next thought:
What the hell are we supposed to do about it?
Myth: Low oil consumption is good.
Reality: Consumption of less than a quart every 20 hours is
not a good sign, because the top piston rings are probably
starving for oil. Accelerated cylinder wear is likely to occur at
some point.
I thought that was interesting, but even more curious was my next thought:
What the hell are we supposed to do about it?
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
-
zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
-
zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
Ha! 
Seriously now, I've got to say that just because some one publishes a rag with an impressive Title about airplane maintenance doesn't make every thing they say gospel.
Example: TBO Advisor's comment about upper ring lubrication strikes me as ridiculous. Modern autos go 200K or farther using no measureable amount of oil whatsoever between oil changes that are much longer chronologically and farther mileage-wise ...and their upper rings don't "starve" for lubrication!
Aircraft engines, being air-cooled, have larger clearances by necessity to accomodate the expansion/contraction of dissimilar metals in their cyls/heads. Their valve-guide clearances are also changing dimensions more than autos, and that accounts for most of the oil consumption of aircraft engines as compared to auto engines (which being liquid-cooled are more stable dimensionally and therefore more tolerant of being mfr'd to tighter clearances....which in turn allows them to run with lower oil consumption figures.)
The comment TBO Advisor makes with regard to "Accelerated cylinder wear is likely to occur at some point. " is self-prophetic. Eventually even tight engines will wear to the point they increase their oil consumption.
And that's NOT a bad thing! (Martha's in jail now.)
Seriously now, I've got to say that just because some one publishes a rag with an impressive Title about airplane maintenance doesn't make every thing they say gospel.
Example: TBO Advisor's comment about upper ring lubrication strikes me as ridiculous. Modern autos go 200K or farther using no measureable amount of oil whatsoever between oil changes that are much longer chronologically and farther mileage-wise ...and their upper rings don't "starve" for lubrication!
Aircraft engines, being air-cooled, have larger clearances by necessity to accomodate the expansion/contraction of dissimilar metals in their cyls/heads. Their valve-guide clearances are also changing dimensions more than autos, and that accounts for most of the oil consumption of aircraft engines as compared to auto engines (which being liquid-cooled are more stable dimensionally and therefore more tolerant of being mfr'd to tighter clearances....which in turn allows them to run with lower oil consumption figures.)
The comment TBO Advisor makes with regard to "Accelerated cylinder wear is likely to occur at some point. " is self-prophetic. Eventually even tight engines will wear to the point they increase their oil consumption.
And that's NOT a bad thing! (Martha's in jail now.)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
going , going GONE
AHHH TANK SAINT ELMO, IMA FINULLY VILLIFIED ER SUMPIN ? ? ?
I am on engine # 4 on ole '93D. I have probably should have written a book on "C145 engines with high oil consumption". Everyowner with which I have ever had conversations about how much oil my engine used would embarras me to hiding in the tool shed. I could never compete with any of them. Thery would report "five hours and just below tne full mark"! In my five hours I had maybe just 3 or 4 quarts left! Occasionally I would look under the "hood" to see if somebody had put a 'Shakey Jake" in there instead of a C145! I have no explanaton of why my experience was so different than others. Maybe their hour meter was way off! My solution: By AeroShell 100 in 55 gallon drums!
Here is my FWI. Oil is a supplimental coolant in air cooled engines as well as being a vital lubricant. It isn't kept in a hermetically sealed vessel like a car radiator so if it is doing it's job lots of it will go away.
All but one of these engines, that I have run on my 170, went to TBO and could have gone further but another newer engine became available at or near those TBO times. I have never had one that used less than 1 quart per hour.
If it ain't broke don't fix it so it will break! Here is my fwi on breaking in a new cylinder. (one or two). If you use the same tactics in trying to break in one cylinder that you used to break in six, you will do some damage to those cyls. that aren't being changed. A proven fact: low altitude - high power settings will cause excessive heat build up and wear. It is a major contributor to shortened cylinder life. Why abuse the five that are working just to "seat rings" in a "substitute?" The rings will eventually seat and the "new guy on the block" will begin to give 60% to 70 % efficiency, much like the others are doing!
My personal feeling is - If one needs new rings they probably all do. I realize that the two most aft cyls. generally get the most wear because of less cooling but the piston travel is the same in each cyl. It isn't that much more expensive to re-ring all of them and break in the new ring job equally.
OK BRUNG ON THU FLAMERS
I am on engine # 4 on ole '93D. I have probably should have written a book on "C145 engines with high oil consumption". Everyowner with which I have ever had conversations about how much oil my engine used would embarras me to hiding in the tool shed. I could never compete with any of them. Thery would report "five hours and just below tne full mark"! In my five hours I had maybe just 3 or 4 quarts left! Occasionally I would look under the "hood" to see if somebody had put a 'Shakey Jake" in there instead of a C145! I have no explanaton of why my experience was so different than others. Maybe their hour meter was way off! My solution: By AeroShell 100 in 55 gallon drums!
Here is my FWI. Oil is a supplimental coolant in air cooled engines as well as being a vital lubricant. It isn't kept in a hermetically sealed vessel like a car radiator so if it is doing it's job lots of it will go away.
All but one of these engines, that I have run on my 170, went to TBO and could have gone further but another newer engine became available at or near those TBO times. I have never had one that used less than 1 quart per hour.
If it ain't broke don't fix it so it will break! Here is my fwi on breaking in a new cylinder. (one or two). If you use the same tactics in trying to break in one cylinder that you used to break in six, you will do some damage to those cyls. that aren't being changed. A proven fact: low altitude - high power settings will cause excessive heat build up and wear. It is a major contributor to shortened cylinder life. Why abuse the five that are working just to "seat rings" in a "substitute?" The rings will eventually seat and the "new guy on the block" will begin to give 60% to 70 % efficiency, much like the others are doing!
My personal feeling is - If one needs new rings they probably all do. I realize that the two most aft cyls. generally get the most wear because of less cooling but the piston travel is the same in each cyl. It isn't that much more expensive to re-ring all of them and break in the new ring job equally.
OK BRUNG ON THU FLAMERS
OLE GAR SEZ - 4 Boats, 4 Planes, 4 houses. I've got to quit collecting!
-
Jr.CubBuilder
- Posts: 517
- Joined: Thu Aug 12, 2004 10:33 pm
rename that plane "Dribbles".I am buying a new airplane... one part at a time! 
I started my annual today, while I was checking my compressions I got all excited because I could see that all of the compressions had gone up since the last annual, that is until I got to the last cylinder (#2). It only registered 58/80. Too low for my comfort level. The air was leaking past the rings. Last year it was the lowest at 64/80.
I am going to at least replace the rings and have the cylinder rehoned/machined (I haven't investigated the requirements yet).
I'm going to have to think about doing the rest of the cylinders, I am just neurotic enough that I may not feel comfortable unless all cylinders have had new rings installed.
Well Gar, I thought my consumption was a little high at 4-5 quarts per hour, in hind sight I guess that's not so bad.
David
I started my annual today, while I was checking my compressions I got all excited because I could see that all of the compressions had gone up since the last annual, that is until I got to the last cylinder (#2). It only registered 58/80. Too low for my comfort level. The air was leaking past the rings. Last year it was the lowest at 64/80.
I am going to at least replace the rings and have the cylinder rehoned/machined (I haven't investigated the requirements yet).
I'm going to have to think about doing the rest of the cylinders, I am just neurotic enough that I may not feel comfortable unless all cylinders have had new rings installed.
Well Gar, I thought my consumption was a little high at 4-5 quarts per hour, in hind sight I guess that's not so bad.
David