Continental 0470 R - Cylinder Replacement Inevitable?

WDD

WDD

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Vintage Snazzy (so my adult children say)
Chatting with a buddy the other day, and he mentioned that the type of engine I have, Continental 0470 R in my 182 P, will never make it to overhaul without replacing at least 2 to 3 cylinders - rings - piston sets.

“These engines just can’t make it all the way to TBO without top end work”.

What say other 0470 owners?
 
I don't know what to say, the commercial outfit I work with never have cylinder trouble with that vintage of O-470's. Maybe we just are not as smart as your buddy. We get 2400 hours out of our Cessnas on floats with those engines. Of course they are flown commercially and not private. Private operators refuse to operate their engines per Continental recommendations.
 
WDD said:
“These engines just can’t make it all the way to TBO without top end work”.
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FWIW: Have seen O-470s go well beyond OH recommendations even in utility ops. As mentioned just need to operate them properly and perform the right mx.
 
MountainDude said:
Can you please summarize the difference(s)?
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The engines are engineered to operate at 75% or more power. Run the engines at the upper range of design operating temperatures and RPMs. The valve opening and closing timing is set for +75% power. The magneto timing is set for 75% power. When operating the engine less then that it does not clean itself and the choke of the cylinders barrels are not expanded as designed.

The engineers that designed these aircraft engines did not design them to run at partial power and doing so is outside the design.
 
WDD said:
Chatting with a buddy the other day, and he mentioned that the type of engine I have, Continental 0470 R in my 182 P, will never make it to overhaul without replacing at least 2 to 3 cylinders - rings - piston sets.

“These engines just can’t make it all the way to TBO without top end work”.

What say other 0470 owners?
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You know, I heard a lot of people tell me that I should never run LOP.

I also had a lot of people tell me something similar to what you're saying about my IO-550 - "You'll never make it to TBO..."

Eventually I realized that the Venn diagram of the two groups above was basically a circle. I'm approaching 2400 hours on the 550 and it's running just fine being operated at 65% LOP, thankyouverymuch.

I don't listen to those people any more.

FWIW, on our club's old 182, we went 951 hours past TBO before it needed an overhaul.

As with any plane: Learn it well, fly it often, and it'll treat you well.
 
The quality of cylinders I've seen coming out of Continental or Superior recently have been junk. Until they've been reworked by a decent cylinder shop I 100% expect them to need work after a few hundred hours. The last one I sent in, the *intake* guides were somehow shot. I operate the engine pretty much by the book.
 
So…. Buy a new steel cylinder and then send it to a machine shop to be trued and honed, and new valve guides inserted?

Some grace needed for an odd question. Why not just re machine the old cylinder, assuming it’s the steel version and not chrome lined?
 
Klaus M said:
The engines are engineered to operate at 75% or more power. Run the engines at the upper range of design operating temperatures and RPMs. The valve opening and closing timing is set for +75% power. The magneto timing is set for 75% power. When operating the engine less then that it does not clean itself and the choke of the cylinders barrels are not expanded as designed.

The engineers that designed these aircraft engines did not design them to run at partial power and doing so is outside the design.
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So one can't fly above 7,000 msl and remain inside the design?
 
Bore scope your cylinders regularly and monitor the appearance of your valves. Burnt valves kills these cylinders. Not sure about your cylinders, but the ones on the 520 and 550's have a rotator (rotocoil) on the exhaust valve that keeps them spinning and running cooler. If the rotator fails the valves will burn.
 
I did a bore scope pre buy. A couple of cylinders showed signs of oil blow by, and sure enough I’m using too much oil, lower compressions. So maybe I do need a cylinder or so. Or redo the ones I have?

Owing an engine new to me - appreciate the help.
 
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WDD said:
Or redo the ones I have?
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Provided there's not something catastrophically wrong with the cylinder, my 1st choice is always to have the current ones reworked by a good shop. I only used J&J Air Part in TX or Gibson in OK but there are others as well.
 
Ah. So it’s not something a local machine shop that reworks engines can do?
 
WDD said:
Ah. So it’s not something a local machine shop that reworks engines can do?
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Depends on their capabilities. Some repairs are outside the scope of what some engine shops can or are willing to do. And depending on the shop, you may not want them touching some things.

Same thing is true for any engine machine work, aircraft or not.
 
WDD said:
So it’s not something a local machine shop that reworks engines can do?
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No on your 182. But even for E/AB applications unless the shop has experience specifically with aircraft engine cylinders they could easily cause an issue. Plus aircraft shops tend to have all the special equipment to pull heads from the cylinder barrel, specs to properly hone out the barrel as some are tapered, etc, etc.
 
Many Powerplant Techs are authorized to sign off the cylinder work.

However; they may not want to do that unless they witness the entire

operation. It’s possible sending jugs to folks that have to equipment,

expertise AND authorization may be fastest and most economical way to go.
 
If you need a cylinder exchange Gibson's is the place to call. They've done good work for me. Prices are cheaper to exchange than it will be for a machine shop.

Gibson Aviation in El Reno, Oklahoma

Gibson Aviation in El Reno, Oklahoma, disassembles, cleans and inspects cylinders and related parts. We are a certified repair station.
www.gibsonaviationok.com www.gibsonaviationok.com
 
WDD said:
Ah. So it’s not something a local machine shop that reworks engines can do?
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Aircraft engines?

FWIW, there's an FBO maintenance shop locally that I have used in the past that is capable of doing quite a bit of cylinder work. If you have an *aircraft* maintenance shop that has been around for a while and has people who know how to do it, that might be your quickest option. Otherwise, shipping them out and back only adds a couple of days and if you use a reputable shop the result should be close to good as new.
 
Speaking of engine shops, has anyone used Popular Grove? How were they for cylinder work?
 
Rcmutz said:
Speaking of engine shops, has anyone used Popular Grove? How were they for cylinder work?
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Yes, I've sent them 5 of my 2004 vintage ECI cylinders from my Cont O300 since 2012, the latest in 2019 but I've spoken to them in the last couple of years on the topic. They've been great for me but I'm close to them here in IL.
In the last 3 years they've pushed me towards a new Continental cylinder vs. IRAN'ing my current cylinders due to price increases on parts (and maybe labor?) for the IRAN approaching new cylinder prices.
I've not had issues with one of their IRAN'd cylinders yet. Knock on wood.
 
Rcmutz said:
Speaking of engine shops, has anyone used Popular Grove? How were they for cylinder work?
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Poplar Grove is excellent. My former flying club has sent several engines and cylinders there, and the work is top quality. They had done the previous overhaul on our 182's engine that went 951 hours over TBO, so we sent it back there again. No complaints whatsoever. I'll be sending my geriatric engine there when it is finally time to do so.
 
Klaus M said:
The engines are engineered to operate at 75% or more power. Run the engines at the upper range of design operating temperatures and RPMs. The valve opening and closing timing is set for +75% power. The magneto timing is set for 75% power. When operating the engine less then that it does not clean itself and the choke of the cylinders barrels are not expanded as designed.

The engineers that designed these aircraft engines did not design them to run at partial power and doing so is outside the design.
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Thank you for the input. That's the first time I read this. Most others are basing their engine ops on either LOP/ROP (2 different schools of thought) or absolute CHTs (some saying the lower the better; others saying to keep it around 380, which I think would be consistent with your input).
 
flyingcheesehead said:
Poplar Grove is excellent. My former flying club has sent several engines and cylinders there, and the work is top quality. They had done the previous overhaul on our 182's engine that went 951 hours over TBO, so we sent it back there again. No complaints whatsoever. I'll be sending my geriatric engine there when it is finally time to do so.
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Thanks for the PIREP. I have heard good things about them in the past and was curious if it was still true.
 
Follow up: Oil consumption was 2 quarts every 3 - 4 hours. Mechanic did an oil leak analysis / procedure and found 3 cylinders with a lot of oil leakage. Probably exhaust valve guides. Pulled the three, sent to aircraft machine shop to be overhauled. One had a broken ring. It also turned out to be too far out of spec to be overhauled, so I bought a new steel cylinder/ piston/ ring set.

All back together, so now I need to break in the new rings with some long X Countries.


Note to self: If anyone asks me about pre buy, do the oil consumption test with the bore scope. Compression numbers are just a small part of how well an engine is running.

Second note: Any sign of RTV sealant means something is being hidden. Pan was also leaking oil. I had to have the oil pan pulled, cleaned, new gasket, and properly torqued.
 
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WDD said:
Chatting with a buddy the other day, and he mentioned that the type of engine I have, Continental 0470 R in my 182 P, will never make it to overhaul without replacing at least 2 to 3 cylinders - rings - piston sets.

“These engines just can’t make it all the way to TBO without top end work”.

What say other 0470 owners?
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LyConasaurs easily make TBO on the bottom. Crank, bearings, etc. The top end usually will need valve work and/or piston rings before TBO.. Regarding the O-470 your buddy's negative opinion of the durability of that engine is the first I've heard in 45yrs
 
Flown 50-70 hours a year, it's not common for engines to need work before TBO, often cylinder related. To much time for corrosion to take it's toll. At > 150 hours per year, they tend to make TBO; > 200 per years nearly always do.
 
Something I learned when moving from an airplane with an O-200 up to a plane with an O-470. the exhaust valve dia is identical in the two engines. The O-200 is 50Cu/in per cyl. the O-470 is 78.3Cu/In per cyl. Various sub-categories of the two engines operate at redline of 2650-2725RPM. Meaning they are moving the air through the same valve dia where there is a 50% increase in cu/in capacity.

I believe that the exhaust service volume of the O-470 valve is larger due to a cam lobe increase height. However, I can't imagine the exhaust passage volume increased by ~50%. Consequently, it's not a surprise that the O-470 engine has a common failing mode of exh valves, seats, guides. It's my opinion that the O-470 exh flow design is compromised.

If anyone has the specs for the opening and duration of the O-200 exh vs the O-470 exh valves, I could calc the effective exh flow volumes and compare. Pretty sure I know what I would find.
 
Barrett50 said:
Consequently, it's not a surprise that the O-470 engine has a common failing mode of exh valves, seats, guides. It's my opinion that the O-470 exh flow design is compromised.
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A regularly flown IO/O-470 is about the most reliable engine around, in the category of a Lyc IO/O-360.

On the other hand, an O-200, while a great engine, IMHO seems has a greatly likelihood of having valve/cylinder issues.

So there's more to the story than in^3/cylinder.
 
Sure there's more to the story than just the volume of air passing the exh valve. I didn't say the valve size was exclusive or determining. However, the TCM SB03-3, while it now refers to all TCM cyl, was originally developed for the O-470 and E-225(470 Cu/In), and later expanded to include all TCM jugs. Figures 6-12 in the SB are all taken from an O-470 engine. One can see this by the distance between the int and exh valves in the figure and the recess below the cyl mounting flange. Still applies to the O-200 jugs as well. I've owned and now own both and I generally have more trouble with the O-470 engine. The valve size shown in the figures show a burn in the O-470 exh valve, not surprising.
 
You’re saying that holding exhaust valve size constant but varying displacement or cylinder size results in some correlation to valve, seat, and guide failure rates? I’ve not heard or seen anything anecdotally, nor in my automotive experience, nor in the academic or professional literature, but my exposure might be limited. Please share more. IO-470-F owner…
 
The same size valve must pass about 45% more hot gas(spent fuel/air) in the O-470 engine during the same exact piston speed. I'm not sure what other factors need to be explained. Either the O-200 exh is way, way over designed or the O-470 will retain more heat in the valve, seat, guide due to the greater volume of gas moving through the cyl.
 
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That’s not how it works. Volume of hot gas traversing across a valve edge has nothing to do with valve longevity. It’s temperature. If the EGT in a 200 cu in engine were less than a 400 cu in engine, then I’d agree. The valve dissipates its heat to the seat to the head to the air or to the stem to the guide to the head to the air. If what you are proposing was correct, you’d also see failures of the adjacent thermal dissipating components.

I don’t think statistics exist, but if you have them, please share. Or something in academic literature, professional journals, mfg SB/AD, etc.
 
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455 Bravo Uniform said:
Volume of hot gas traversing across a valve edge has nothing to do with valve longevity. It’s temperature.
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Let me put my college physics class to work to make a guess.

I’d say it’s the amount of heat energy that’s key. That extra heat energy makes it hotter, which as you say affects longevity.

If the 0470 exhaust valve is the same size, mass and material as the 0200, but has a longer open dwell with more hot gas bathing it, that exhaust gas will impart more heat energy into the valve. Thus the temperature of the 0470 exhaust valve, seat, valve guide, etc is probably running hotter vs what you see on the 0200. There just isn’t time enough to dissipate the extra heat energy to make it cooler. This just a guess however. Data should exist on whether this is true or not.
 
WDD said:
Let me put my college physics class to work to make a guess.

I’d say it’s the amount of heat energy that’s key. That extra heat energy makes it hotter, which as you say affects longevity.

If the 0470 exhaust valve is the same size, mass and material as the 0200, but has a longer open dwell with more hot gas bathing it, that exhaust gas will impart more heat energy into the valve. Thus the temperature of the 0470 exhaust valve, seat, valve guide, etc is probably running hotter vs what you see on the 0200. There just isn’t time enough to dissipate the extra heat energy to make it cooler. This just a guess however. Data should exist on whether this is true or not.
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Wouldn’t that show up as imcreased EGT and/ or CHTs?
 
StraightnLevel said:
Wouldn’t that show up as imcreased EGT and/ or CHTs?
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EGT - I would guess no. What would cool the exhaust temp on the 0200 before it got to the EGT probe? Maybe passing over cooler exhaust valves ???

CHT-
How much does CHT reflect the exhaust valve temp specifically vs the rest of the head?

Just guessing - surely there is data on valve temps, and more to the point valve and valve components longevity 0200 vs 0470.
 
Thermodynamics says that increased pressure of a gas produces adiabatic heat. which is why the compression readings of a 10:1 C/R is greater than 10X the MP. In a thermo-static condition, the gas flow of the larger volume would create a higher adiabatic temp of the gas flow in the O-470 compared to the O-200. Set all other things equal(Moles of air, and of burned HCs, comp ratio, exhaust gas temp at BDC) and there will be a higher temp across the same size valve head, as the gas moves from the cyl to the exhaust port, unless the cylinder of the open valve is greater by lift and possibly by duration. Both of those have engineering limits defined by the head size, stroke, RPM.

While I had the 470 cylinder off for renovation, I asked the shop foreman his opinion and he's the one who showed me the size of the two valves were the same. His shop did all cylinder work and he had about 3x more 470 cyl in for exh work than the O-200. I can call and ask if he has any reference for the difference in repairs between the two. It was his opinion that I shared here about the higher total pressure due to adiabatic heating of the greater gas pressure as it exists the valve and port.

I'm wondering if anyone has fitted EGT gauges on both engines, and if there is a concomitant difference in temps all other things being equal. My experience is two 470 jugs rebuilt and so far no C-90(early version O-200) work needed.
 
Number of cylinders through a shop is often indicative of what's out there in field being flown, as opposed to what has an intrinsically higher or lower failure rate.

For the 470, what was its history before you had it? Factory new with 10 hours or field overhaul 20 years ago with overhauled jugs? Same question for the O-200. Anecdotal reports aside, in general I wouldn't characterize the O-470 cylinders as less reliable than an O-200 - the reverse if far more often postulated.

Have personally put over 2000 hours on -470 and -520 jugs in the past ten years. However, in each instance, started with a complete top overhaul and brand new cylinders. Never an issue, with compressions > 74 and oil burn of about 1/20 quarts across three engines. A small Continental also flown hundred of hours following a top overhaul with no issues.

Personally, believe the secret sauce is start with new cylinders, break them in well on long high-powered flights, and fly them often. Omit any of these three, and results may differ.
 
How many 470 are in service vs 200? Also, the 470 has 50% more cylinders than the 200. Those numbers will dictate the number of cylinders that show up in a shop for service.
 
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