Cylinder temp with new cylinders

neilw2

neilw2

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Neil W
Quick question-

I just got 2 cylinders overhauled on my o-470u. First flight with them today I noticed my CHT showed cylinder temps higher than usual. Not red line but closer than I was used to.


Anything to worry about or normal when the cylinders are breaking in?
 
Very normal until the rings have seated. Did your mechanic provide you with break-in instructions?
 
kyleb said:
Very normal until the rings have seated. Did your mechanic provide you with break-in instructions?
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yes, he had me run it at full power for 3 min then 75% power for 7 minutes and repeat 3 more times.

I figured it was ok but wanted a to double check and the mechanic isn't in till tomorrow.
 
What documentation and instructions came with the new jugs?
 
James331 said:
What documentation and instructions came with the new jugs?
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None except a large invoice ;)

He just had a phone conversation with me about the break in before I picked it up.
 
neilw2 said:
None except a large invoice ;)

He just had a phone conversation with me about the break in before I picked it up.
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You might want to have a read through Continental Service Bulletin M89-7R1 "ENGINE OPERATION AFTER CYLINDER REPLACEMENT AND/OR MAJOR OVERHAUL"
 
[QUOTEis a HELL "neilw2, post: 2073739, member: 17574"]None except a large invoice ;)

He just had a phone conversation with me about the break in before I picked it up.[/QUOTE]
There is a HELL of a lot more to breaking in cylinders than that. Read the stuff suggested above before you glaze those cylinders.
 
flyingriki said:
[QUOTEis a HELL "neilw2, post: 2073739, member: 17574"]None except a large invoice ;)

He just had a phone conversation with me about the break in before I picked it up.
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There is a HELL of a lot more to breaking in cylinders than that.[/QUOTE]
like what?
 
Going through the same thing (3 cylinders).
Was told to run ROP for long periods at very hi temps until the rings seat.
Then that guy's boss said, don't do that, just fly the plane and then bring it back in 20 hours and we will check the through bolts.

I have no idea if anyone knows what is good or bad.
For every opinion, there is an equal opposite opinion.

It is confusing as hell.
 
SixPapaCharlie said:
Going through the same thing (3 cylinders).
Was told to run ROP for long periods at very hi temps until the rings seat.
Then that guy's boss said, don't do that, just fly the plane and then bring it back in 20 hours and we will check the through bolts.

I have no idea if anyone knows what is good or bad.
For every opinion, there is an equal opposite opinion.

It is confusing as hell.
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I can't recall ever reading a Manufacturer's Service Bulletin that was written as though it was an opinion.
 
GRG55 said:
I can't recall ever reading a Manufacturer's Service Bulletin that was written as though it was an opinion.
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I get that but the document says do not exceed 400 degrees.
I SYN, the Mx said you want to run them over 400 degrees for the first couple hours.

Then his boss says "no" do it this way.
I wish the Mx would go "Do it like this SB says"
 
I've read plenty of horror stories about things that have gone wrong from not explicitly following SBs or ADs to the letter.

I've not heard many horror stories from sticking to what the manufacturers say to do.
 
SixPapaCharlie said:
I get that but the document says do not exceed 400 degrees.
I SYN, the Mx said you want to run them over 400 degrees for the first couple hours.

Then his boss says "no" do it this way.
I wish the Mx would go "Do it like this SB says"
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I believe the main issue with CHT is the head to cylinder connection. The heads are aluminum alloy and the cylinder barrels are steel. The strength of the alloy heads falls off dramatically at abnormally high temperature and there is risk of failure at the connection if the engine is run that way habitually. If the manufacturer says do not exceed 400 deg I would pay heed to that.

There are likely engine operating instructions in the POH. There are operating specifications from the engine manufacturers. And there are SBs for specific maintenance circumstances. Those are probably the best starting references. If an "expert" is telling you to do something contrary to these might be best to get a technical explanation as to why from them.
 
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The cylinder shops are now using techniques and practices that were never heard of when all those SBs were written, and old wives tales were taught.

When the new methods are used, the rings will be seated by the time you reach pattern altitude.

The run it hard method of cylinder brake in was thought of when we used cast iron rings in chrome cylinders.

The new cylinders we buy today are not Chrome, most are nitrided steel, finished with a fine hone, and chrome rings, these cylinders will have seated the rings very quickly.
The ECI cylinders I use on the 0-200/0-300 don't use a drop of oil from day 1, when I return your engine to service you can fly it normally.
 
I always run mine full rich and wide open throttle for the first 25 hours with mineral oil.
You want to fly wide open at a low altitude so the engine makes power. I was always told run it like you hate it.
 
It isn't news that new cylinders make metal in order to break in the rings. That makes CHTs hotter than normal for a few hours at most. I've never had cylinders require more than 2-3 hours to break in. High cylinder pressures are required to seat rings and high airflows are required to keep things cool. Breaking in is easier with a CS prop. Keep MP high and run it fast and those temps should drop in an hour or two. In the meantime you can manage your CHTs with mixture and cowl flaps. Doing so won't delay break in.
 
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pigpenracing said:
I always run mine full rich and wide open throttle for the first 25 hours with mineral oil.
You want to fly wide open at a low altitude so the engine makes power. I was always told run it like you hate it.
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Why did we use mineral oil in the days of old?
Answer-- we did't have filters.
 
Stewartb said:
It isn't news that new cylinders make metal in order to break in the rings. That makes CHTs hotter than normal for a few hours at most. I've never had cylinders require more than 2-3 hours to break in. High cylinder pressures are required to seat rings and high airflows are required to keep things cool. Breaking in is easier with a CS prop. Keep MP high and run it fast and those temps should drop in an hour or two. In the meantime you can manage your CHTs with mixture and cowl flaps. Doing so won't delay break in.
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OLD WIVES TALE, has been debunked so many time I can't count.
 
Tom-D said:
OLD WIVES TALE, has been debunked so many time I can't count.
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Don't bother, Tom. There are too many "experts" in here who have never greased a wrench in the last ten years that know WAY more than you do. BTW, an "ex" is a has-been, and a "spurt" is a drip under pressure.

The O-470 is an engine straight out of the 1940s with modern technology from the crank on up. The service bulletin was written for a 1940s engine, probably rewritten with some changes in the 1960s and is most probably woefully out of date. Just for $#i+s and giggles, what is the date on the SB?

Yes, manufacturer's documents ARE opinions. They were not delivered from on high with stone tablets. Some human being set pen to paper and it is their OPINION as to how to best do a procedure. Those of us in the field who have to make the machine work have more information technology at our disposal than all the libraries in the world put together fifty years ago. If it happened yesterday it is all over the 'net by this morning.

Even the Supreme Court doesn't issue a directive. They call it an "opinion", remember? And they aren't necessarily correct for all time. "Dred Scott" was nearly totally reversed by "Brown vs. Board of Education". Things change over time. Service Bulletins may have been correct when published and outdated a day, a week, or a century later. But they will almost always be outdated at some point. Steel rings and chrome barrels were once all the rage. Now steel barrels and chrome rings are in and for good reason. Live with it.

Jim
 
Tom-D said:
OLD WIVES TALE, has been debunked so many time I can't count.
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Debunked? By whom? Can you provide references that support that comment?

What happens to the sharp ridges of a freshly honed cylinder wall when the piston rings run up and down during the initial hours? Let's stay with steel cylinders for the discussion. You like to think of yourself as a teacher. Teach.
 
And to the OP, here's your manufacturer's published paper on breaking in engines and cylinders. It talks specifically about why new cylinders run warmer and what to expect as they break in.
http://www.airpowerinc.com/downloads/PDFs/TCMEngineBreakInFlightTips.pdf

If your 470 is using nickel cylinders you should refer to the Titan recommendations (linked earlier in this thread) or perhaps the nickel cylinder instructions published by RAM, who is generally looked upon as a big bore TCM engine expert. The instructions are essentially the same but nickel cylinders break in quicker so the instructions are for one flight.
http://www.ramaircraft.com/Maintenance-Tips/Replacement-Cylinders-Break-In-Flight.htm
 
And to weird jim's typical say-nothing/criticize whatever anyone else says post? My personal 0-470-50 is equipped with Millennium cylinders. Here's the SAP break-in instructions. No 1940s procedures here. http://www.superiorairparts.com/downloads/serviceletters/L96-08.pdf

Coincidentally I have an order in place for a new Superior XP engine and even though it'll be run for an hour in the test cell I'll use the same instructions to complete the break in for that engine.
 
Stewartb said:
And to weird jim's typical say-nothing/criticize whatever anyone else says post? .
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I was just waiting to see if any of you decided to ask the OP for the critical information you need to have before spouting off about this and that method of break-in. All you know is that the OP has "overhauled" cylinders. His old cylinders? Some used but serviceable cylinders? Chromed back to standard with iron rings? Nitrided cylinders with chrome rings? All you know is that he has two cylinders to hang on his airplane. Why not get what you need for information before going off on a tangent?

Me? I want the OVERHAULER'S instructions, not second hand from a phone conversation. I want it in writing before I start going off in half a dozen different directions.

Jim
 
weirdjim said:
I was just waiting to see if any of you decided to ask the OP for the critical information you need to have before spouting off about this and that method of break-in. All you know is that the OP has "overhauled" cylinders. His old cylinders? Some used but serviceable cylinders? Chromed back to standard with iron rings? Nitrided cylinders with chrome rings? All you know is that he has two cylinders to hang on his airplane. Why not get what you need for information before going off on a tangent?

Me? I want the OVERHAULER'S instructions, not second hand from a phone conversation. I want it in writing before I start going off in half a dozen different directions.

Jim
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Thanks for all responses. The cylinders are my old cylinders that were overhauled at a local shop.

I will check with them to see what they say...
 
LOL Yet another POA thread now firmly in the realm of evangelical fervor.

The "89" in M89-7R1 is the year it was issued.

I see the error in my ways. The manufacturers clearly don't know shzt about their products. And all that "modern from the crank up" stuff must have been done by elves using the vast internet library? :D

I'm just hoping the Jehovah Witnesses don't come around knocking on my door this afternoon while I'm in this vulnerable ready-to-convert frame of mind.
 
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Stewartb said:
Debunked? By whom? Can you provide references that support that comment?

What happens to the sharp ridges of a freshly honed cylinder wall when the piston rings run up and down during the initial hours? Let's stay with steel cylinders for the discussion. You like to think of yourself as a teacher. Teach.
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Fine stones don't leave rough edges. I'll show pictures later.
 
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