Continental O-200 Top End Longevity

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Bathman

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Bathman
I would go as far as saying that's it pretty standard that an O-200 will need top end work between 800 to 1200 hours. Why is this? Is the design poor?

I’ve heard some hanger talk that is you work them hard then they last longer? I cruise at 2350rpm. Would increasing that help?

Other people claim things are better if you run then on a mix of Autogas and 10LL again does anyone have any opinions of that?

I’ve also heard that EFI used to produce a better cylinder than Continental or superior. Was there any truth in this and if so is that cylinder still available?
 
Who knows the real answer but I’ve seen lots of O-200 cylinders lately and have some ideas. The ones I’ve seen that have been pulled off were not worn out. I’ve honed and put new rings and lapped the valves in then and the return to normal. The ones I’ve seen have had severe carbon buildup on the piston, ring grooves, and valves. I hear it all the time that “I don’t mess with the mixture”. This will lead to excessive carbon buildup as well as being too easy on it. I run mine pretty easy (2400 rpm) most of the time. I also run mostly Mogas but use 100LL occasionally. I lean aggressively as you will not hurt it running such a low power setting (remember 2600 is 75% at 2,500 ft).
 
Tom-D said:
yes the 0-200-/0-300 will need work around 1000 +-

reason? we are running 100LL when it was designed to run 80/87
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What Tom said. I ran 1/4 100LL 3/4 Mogas, or straight mogas and never had any issues. But I will admit that I have never run one from overhaul to overhaul to see if it would make it without top end work.
 
Greg Bockelman said:
What Tom said. I ran 1/4 100LL 3/4 Mogas, or straight mogas and never had any issues. But I will admit that I have never run one from overhaul to overhaul to see if it would make it without top end work.
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Actually there are so many variables it's impossible to tell
 
So these variables does running at a higher rpm and leaning aggressively have any impact?

Mogas isn't an option sadly
 
Bathman said:
So these variables does running at a higher rpm and leaning aggressively have any impact?

Mogas isn't an option sadly
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Proper leaning is probably more important than running aggressively. However taking it easy and not leaning is certainly going to hurt you. The O-200 runs at higher RPM than most people are accustomed to so they tend to run them at 24-2500 rpm instead of the 2600+ they require to make 75%. There are a surprising number of people who don’t use the mixture too.
 
Grum.Man said:
Proper leaning is probably more important than running aggressively. However taking it easy and not leaning is certainly going to hurt you. The O-200 runs at higher RPM than most people are accustomed to so they tend to run them at 24-2500 rpm instead of the 2600+ they require to make 75%. There are a surprising number of people who don’t use the mixture too.
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I lean a lot in my 150, even in climbs above 2500’ to get the most power and I run straight mogas nearly all the time, but don’t think that running 75% is necessary. Why would it matter to run it harder as long as you lean as far as it can go/to max RPM? What is magic about 75%, other than that is where you are “allowed” to run continuously in cruise. Is this just a 100LL thing and that is why I don’t worry about it?
 
Matthew Rogers said:
I lean a lot in my 150, even in climbs above 2500’ to get the most power and I run straight mogas nearly all the time, but don’t think that running 75% is necessary. Why would it matter to run it harder as long as you lean as far as it can go/to max RPM? What is magic about 75%, other than that is where you are “allowed” to run continuously in cruise. Is this just a 100LL thing and that is why I don’t worry about it?
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nothing magic at all, it’s just the hardest I would run it. Most required top end work is caused my the exhaust valve not seating properly. The higher rpm, pressures, and temperatures will help prevent carbon deposited from forming and keep the valve rotating.
 
Bathman said:
I’ve also heard that EFI used to produce a better cylinder than Continental or superior. Was there any truth in this and if so is that cylinder still available?
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I've never heard of EFI cylinders, but I replaced the OEM TCM cylinders with ECi Titan Cerminil cylinders, and have had really good luck with them. My Continental cylinders were plagued with carbon build-up in the valve guides resulting in two incidents of stuck exhaust valves in different cylinders. The ECi Titans have valve rotators similar to Continental's bigger engines, and I haven't experienced any valve guide carbon buildup with them. Also, the coating on the cylinder walls seems to do a better job of resisting corrosion than the TCM cylinders.

Sadly, they are no longer available unless you're lucky enough to find some new old stock somewhere. My $.02.

O200cutaway.jpg
 
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Matthew Rogers said:
Why would it matter to run it harder as long as you lean as far as it can go/to max RPM? What is magic about 75%, other than that is where you are “allowed” to run continuously in cruise. Is this just a 100LL thing and that is why I don’t worry about it?
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Leaning the engine at high power settings increases the risk of detonation, so the engine manufacturers have leaning recommendations to keep you out of trouble. You ignore such advice at your own peril. You might get away with it in a little O-200, but take that technique into bigger engines and you could start dismantling the engine in flight.

Detonation is poorly understood by many pilots. Detonation is the spontaneous combustion of some portion of the fuel/air mix in the cylinder, caused by the heat and pressure of the advancing flame front of normal combustion. It creates a pressure spike that elevates temperatures and melts stuff, it cracks things, and it scrubs metal off pistons and so on. Lower-octane fuels are more prone to detonation. Slow-turning engines, like aircraft engines, are more prone to it. Large cylinders (aircraft engines again) are more prone. Lean mixtures make it more likely. Hotter intake charges are more likely to detonate (turbocharging, or too much carb heat at full power). Detonation needs time to develop, which is why slow, big-bore engines are more susceptible. Lean mixtures burn more slowly. Turbocharging increases the cylinder pressures and temperatures that cause the complex fuel molecules to break down into simpler structures that easily autoignite. More spark advance leads to earlier and higher cylinder pressures that can lead to detonation.

The computers in your car adjust spark timing and fuel mixture to avoid detonation. We we were young we had no computers in cars and we learned to use the throttle and gearshift to avoid lugging the engine causing "pinging" or "spark knock" so we wouldn't bust the engine. In airplanes there's too much other noise and you can't hear it, so we follow the POH and everything's good.

https://blog.aopa.org/aopa/2015/04/13/destroy-your-engine/
 
Dan Thomas said:
Leaning the engine at high power settings increases the risk of detonation,
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this has been disproven long ago. There are several reasons for detonation but lean mixtures isn't one of them.
When the mixture is to lean, there isn't enough to fuel to detonation.
 
Tom-D said:
this has been disproven long ago. There are several reasons for detonation but lean mixtures isn't one of them.
When the mixture is to lean, there isn't enough to fuel to detonation.
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"With the given that the fuel is the correct choice for the engine, for a pilot the number one cause of detonation is excessive leaning at high power settings."

https://www.lycoming.com/node/17607

FWIW,

Dale
 
Stan Cooper said:
... I replaced the OEM TCM cylinders with ECi Titan Cerminil cylinders, and have had really good luck with them. ...

Sadly, they are no longer available unless you're lucky enough to find some new old stock somewhere. My $.02.
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Continental bought ECi and offers NiC3 (Nickel Silicon Carbide) cylinders. I am guessing they are ECi Titan cylinders.
https://www.continentalmotors.aero/parts/cylinder-features.aspx

Original ECi info: https://www.dropbox.com/s/is41xyqeiixka3v/ECi.Nickel+Carbide.Cylinders.pdf?dl=1
 
It's not the cylinder walls or pistons or rings that small Continentals come up short on. It's the valves and guides. In 1999 Lycoming started using a high-chromium-content bronze for their guides, and the wear problems mostly went away. Continental might still be using the same stuff they've used since the '40s or something. And Lyc's exhaust valves are sodium-filled to carry the heat away into the guide much faster.

The manufacturers of air-cooled engines have to use guide material with similar coefficients of linear thermal expansion, or the guide will come loose, or expand more than the head and stretch the guide bore, which also leaves it loose when it cools down. Bronze and aluminum are almost identical that way. Steel or iron expand at half the rate of bronze or aluminum. Options are limited. Cars with aluminum heads are liquid-cooled, keeping temps within manageable limits not available to aircraft engines.
 
Dan Thomas said:
It's not the cylinder walls or pistons or rings that small Continentals come up short on. It's the valves and guides. In 1999 Lycoming started using a high-chromium-content bronze for their guides, and the wear problems mostly went away. Continental might still be using the same stuff they've used since the '40s or something. And Lyc's exhaust valves are sodium-filled to carry the heat away into the guide much faster.
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As the illustration in post #12 shows, ECi used chrome plated exhaust valve stems and High Chromium Ni-Resist exhaust valve guides in their O-200 Titan Cerminil cylinders along with rotocoils (valve rotators that scrub contaminants off the valve face by causing valve rotation). It's a shame Continental dropped the small engine ECi cylinders after they acquired the company.
 
Dan Thomas said:
It's not the cylinder walls or pistons or rings that small Continentals come up short on. It's the valves and guides. In 1999 Lycoming started using a high-chromium-content bronze for their guides,
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Why discuss two different engine when trying to discover difference.

there is a lot of different reasons the 0-200/300 has different problems the Lycoming has that the TCM engine doesn't.
 
Dan Thomas said:
It's not the cylinder walls or pistons or rings that small Continentals come up short on. It's the valves and guides. In 1999 Lycoming started using a high-chromium-content bronze for their guides, and the wear problems mostly went away. Continental might still be using the same stuff they've used since the '40s or something. And Lyc's exhaust valves are sodium-filled to carry the heat away into the guide much faster.
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Dan, are you aware of any changes in the design of the valve seats in the O-200-A factory-built after 2000 or so? I had a new O-200-A in a 2007 Sport Cub that needed a top at 125 hours TTSN due to all four exhaust valves leaking and compressions down to 40 or 50. I've flown, owned and instructed in O-200-A-equipped airplanes since the 1960s, so I know how to operate them successfully. I heard that a sizeable number of Sport Cub owners had the same problem, but cylinders that were re-worked in the field performed ok.

(Note, I'm not talking about the O-200-D that was in the C-162).
 
Pilawt said:
Dan, are you aware of any changes in the design of the valve seats in the O-200-A factory-built after 2000 or so? I had a new O-200-A in a 2007 Sport Cub that needed a top at 125 hours TTSN due to all four exhaust valves leaking and compressions down to 40 or 50. I've flown, owned and instructed in O-200-A-equipped airplanes since the 1960s, so I know how to operate them successfully. I heard that a sizeable number of Sport Cub owners had the same problem, but cylinders that were re-worked in the field performed ok.

(Note, I'm not talking about the O-200-D that was in the C-162).
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Nothing definite, but quality control in a lot of aircraft stuff, from mags to alternators to engines to tires and instruments has been an issue the last decade or more. One thing I've seen is that the small Continentals, designed for 80-octane fuel, don't care for 100LL or Mogas too much. They need a bit of lead for the valve seat and stem lube; too much (100LL has four times as much as 80) can foul things up, and too little (Mogas has none) results in accelerated wear. But for your engine to need TOH at 125 hours implies something defective.
 
In a couple of cases I've seen cylinder head castings that had poorly aligned core elements. The as-cast fins would seem to me to partially restrict the cooling air flow. Any others seen this?
 
Dan Thomas said:
Nothing definite, but quality control in a lot of aircraft stuff, from mags to alternators to engines to tires and instruments has been an issue the last decade or more. One thing I've seen is that the small Continentals, designed for 80-octane fuel, don't care for 100LL or Mogas too much. They need a bit of lead for the valve seat and stem lube; too much (100LL has four times as much as 80) can foul things up, and too little (Mogas has none) results in accelerated wear. But for your engine to need TOH at 125 hours implies something defective.
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Since it hasn't been mentioned yet in this discussion of small Continental engines.

Marvel Mystery Oil (MMO).
 
nrpetersen said:
In a couple of cases I've seen cylinder head castings that had poorly aligned core elements. The as-cast fins would seem to me to partially restrict the cooling air flow. Any others seen this?
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On some cylinders I've seen stuff located off-center, like the injector port drilled close to the edge of the casting boss in the head. There was, for example, an AD against some heads regarding cracking that seemed to be related to that. https://rgl.faa.gov/Regulatory_and_...5763900528277/$FILE/2009-19-07_Correction.pdf
 
And the problem has reared its head again.


272 hours and just over 2 years on a factory rebuilt O-200 ($29400) I had low compressions on one cylinder. This was pulled, the guide reamed and reseated.


Then 3 weeks later and at 323 hours low compression was found on two more cylinders.


Oil filter fitted, leaned on ground, oil changed every 25 hours.


Thoughts?


Continental can no longer make decent cylinders?
 
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JAWS said:
Since it hasn't been mentioned yet in this discussion of small Continental engines.

Marvel Mystery Oil (MMO).
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4 oz. in ten gallons along with conservative leaning, unless you have adequate instrumentation for it, and these problems go away.
 
455 Bravo Uniform said:
What are considered low compressions on O-200s?
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You are "allowed" to go really low by Continental (just like the manufacturers figures for oil consumption per hour - too high for anyone to really trust). Others will tell you that a leak down test is not very accurate or telling. Especially since you can perform it and get one number, do it again and get a wildly different number, do it on another day and get a third number.
 
Matthew Rogers said:
You are "allowed" to go really low by Continental (just like the manufacturers figures for oil consumption per hour - too high for anyone to really trust). Others will tell you that a leak down test is not very accurate or telling. Especially since you can perform it and get one number, do it again and get a wildly different number, do it on another day and get a third number.
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If you're getting wildly different numbers, you're not doing it right. The rings have to be seated, and to get them there you usually have to wiggle the prop a bit with the pressure in the cylinder. Then the number jumps back to where it should be. If the number is bad, you listen at the oil filler or dipstick hole; hearing a hiss there means ring leakage. At the exhaust is an exhaust leak, and at the induction inlet it's an intake valve leak. Before one takes the cylinder off to start valve leaks, the rocker cover comes off and with pressure in the cylinder you tap the rockers over the valves with a soft hammer, making the valve pop some air out. In many cases the leak stops. Just removing the sparkplugs dislodges bits of carbon that can fall onto the face of an open valve and interfere with its seating and cause the leak. Popping the valve blows that out.

Continental has a gauging tool for determining the acceptable leakage rate. It's nothing more than a fitting that has a calibrated orifice in it. You attach the sparkplug hole fitting to it and bring the primary pressure up to 80 PSI; whatever the secondary pressure says is the acceptable leakage rate for that day. I usually found it at around 43/80. That's pretty bad. The barometric pressure/altitude, temperature and humidity will all affect the reading a little bit. Altitude and temp the most.
 
Wiggling the prop is a must to find the maximum pressure point when the compression rings are fully seated.

WARNING: If you wiggle too much the piston can roll over TDC and flip the prop. It may seem obvious to say, "Keep your head out of the prop arc," but some who know better have been tagged. (Don't ask how I know). Depending on whether you are right or left handed and how your prop indexes you may need to take ALL the readings from one side of the engine.

SUGGESTION: Pressurize the cylinder halfway, find the sweet spot, then go to 80 psi.
 
Domenick said:
Wiggling the prop is a must to find the maximum pressure point when the compression rings are fully seated.

WARNING: If you wiggle too much the piston can roll over TDC and flip the prop. It may seem obvious to say, "Keep your head out of the prop arc," but some who know better have been tagged. (Don't ask how I know). Depending on whether you are right or left handed and how your prop indexes you may need to take ALL the readings from one side of the engine.

SUGGESTION: Pressurize the cylinder halfway, find the sweet spot, then go to 80 psi.
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I built my own compression tester. It has a lever-adjusted regulator and you squeeze it like you would squeeze a caulking gun. You can bring the pressure up some, wiggle the prop, then go to 80 and take the reading. If something starts to get away on you, just release the pressure on the lever and a quick-release valve inside the regulator instantly dumps all the pressure. Never patented it; the cost of doing so for an item that would sell so few copies probably isn't worth it, and too much machining is involved. The price would discourage most buyers. Pretty hard to beat the cheap little differential compression testers that are just an aluminum block with a calibrated orifice in it, a $5 plastic regulator and two gauges.
 
Not sure if they are willing to talk to ya, but CP Aviation at Santa Paula (KSZP) has been running a fleet of 150's at their flight training school for a couple of decades, I bet the owner/ head mechanic Clay has some real world data. I know they ream the the exhaust guides every 500 hrs as standard opperating procedure after N704UT had to land in a wash with a stuck valve many years ago.
 
G-force said:
Not sure if they are willing to talk to ya, but CP Aviation at Santa Paula (KSZP) has been running a fleet of 150's at their flight training school for a couple of decades, I bet the owner/ head mechanic Clay has some real world data. I know they ream the the exhaust guides every 500 hrs as standard opperating procedure after N704UT had to land in a wash with a stuck valve many years ago.
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If the rebuilder sets the valve-guide clearance too tight, any carbon buildup on the stem will make it stick. I had to take the engine off a 150 and take it back to the overhauler to get that corrected.
upload_2021-6-15_10-2-41.png

upload_2021-6-15_10-2-19.png

Look at the difference in clearances between new limits and the service limit. Also note the tighter spec on the O-200 compared to its predecessors. I think the engine we had trouble with likely had less than the new minimum clearance. If the overhauler isn't following the tables closely, he might feel that .003" feels way too loose and not ream the guide enough.
 
G-force said:
Not sure if they are willing to talk to ya, but CP Aviation at Santa Paula (KSZP) has been running a fleet of 150's at their flight training school for a couple of decades, I bet the owner/ head mechanic Clay has some real world data. I know they ream the the exhaust guides every 500 hrs as standard opperating procedure after N704UT had to land in a wash with a stuck valve many years ago
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Thank you.

B
 
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