Vance Harral Posted November 13 Report Posted November 13 Our partnership voted this week to order an overhaul exchange IO-360-A1A from Ly-Con (lead time is currently advertised as 8 months, though we're fully prepared for it to be much longer). The current engine is actually running fine - good compressions, oil analysis, and borescope. But it leaks an embarrassing amount of oil from various nooks and crannies, the long lead times on engines change the "run it till it breaks" logic a bit, and after almost 35 years and 2600 hours we just feel like it's time. The purpose of this thread is to pick the brains of the well-educated folks here about options Ly-Con offers on an IO-360 overhaul. The floor is open for opinions on: FACTORY NEW LYCOMING CYLINDERS: We're inclined to do this, but even if we weren't, I don't actually think it's an "option". It's my understanding that at this time and for the foreseeable future, there is a dearth of donor angle-valve cylinders, such that you're going to need new ones unless you actually send in your own engine and wait months/years for the shop to overhaul the cylinders you send. PORT FLOW & BALANCE CYLINDERS: We understand the premise, but speculate the result is a tiny horsepower difference that is only meaningful if you're trying to win a race. STRIP PAINT FROM CYLINDERS, PAINT BARRELS BLACK, ALODINE HEADS FOR IMPROVED COOLING: Undoubtedly looks sharp on delivery, but we're very skeptical it makes any difference in cooling, and worry how the appearance will hold up over time. SPECIAL COATINGS ON PISTONS, VALVES, AND SPRINGS, DLC COATED ROCKER SHAFTS AND PISTON PINS: these are relatively inexpensive options that seem likely to reduce the risk of corrosion and wear. But the airplane lives in a dry climate, and the last engine has lasted decades without them. It's unclear to us if these "new" coatings have been around long enough in aircraft piston engines to feel confident they don't have some not-yet-discovered vulnerability that makes the cure worse than the disease. LY-CON CRANKCASE O-RING MODIFICATION STC SE001954SE: this STC modifies the crankcase halves to machine a groove which holds a sealant ring at assembly, rather than using the traditional silk thread. It's the most interesting option to us, and the subject of much discussion. We're all about anything that reduces oil leaks, having been irritated by them for decades, and this method seems to require less in the way of "magic hands" to get right. But this is a one-way modification, you can't go back to silk thread once it's done. It's unclear what sealant material goes in the groove and how well it holds up over time vs. a theoretically-perfect silk thread job. We also wonder what the implications are if one needs future engine work that requires the crankcase to be split, by a shop that's not Ly-Con. If anyone here has direct experience with any of these options, I'd love to hear about it. In the spirit of Mooneyspace, rampant speculation is also welcome, of course.
Slick Nick Posted November 13 Report Posted November 13 Where’s it leaking oil from? If compressions and borescopes are good with clean oil analysis, seems silly to overhaul because of an oil leak. 2
Ragsf15e Posted November 13 Report Posted November 13 57 minutes ago, Vance Harral said: Our partnership voted this week to order an overhaul exchange IO-360-A1A from Ly-Con (lead time is currently advertised as 8 months, though we're fully prepared for it to be much longer). The current engine is actually running fine - good compressions, oil analysis, and borescope. But it leaks an embarrassing amount of oil from various nooks and crannies, the long lead times on engines change the "run it till it breaks" logic a bit, and after almost 35 years and 2600 hours we just feel like it's time. The purpose of this thread is to pick the brains of the well-educated folks here about options Ly-Con offers on an IO-360 overhaul. The floor is open for opinions on: FACTORY NEW LYCOMING CYLINDERS: We're inclined to do this, but even if we weren't, I don't actually think it's an "option". It's my understanding that at this time and for the foreseeable future, there is a dearth of donor angle-valve cylinders, such that you're going to need new ones unless you actually send in your own engine and wait months/years for the shop to overhaul the cylinders you send. PORT FLOW & BALANCE CYLINDERS: We understand the premise, but speculate the result is a tiny horsepower difference that is only meaningful if you're trying to win a race. STRIP PAINT FROM CYLINDERS, PAINT BARRELS BLACK, ALODINE HEADS FOR IMPROVED COOLING: Undoubtedly looks sharp on delivery, but we're very skeptical it makes any difference in cooling, and worry how the appearance will hold up over time. SPECIAL COATINGS ON PISTONS, VALVES, AND SPRINGS, DLC COATED ROCKER SHAFTS AND PISTON PINS: these are relatively inexpensive options that seem likely to reduce the risk of corrosion and wear. But the airplane lives in a dry climate, and the last engine has lasted decades without them. It's unclear to us if these "new" coatings have been around long enough in aircraft piston engines to feel confident they don't have some not-yet-discovered vulnerability that makes the cure worse than the disease. LY-CON CRANKCASE O-RING MODIFICATION STC SE001954SE: this STC modifies the crankcase halves to machine a groove which holds a sealant ring at assembly, rather than using the traditional silk thread. It's the most interesting option to us, and the subject of much discussion. We're all about anything that reduces oil leaks, having been irritated by them for decades, and this method seems to require less in the way of "magic hands" to get right. But this is a one-way modification, you can't go back to silk thread once it's done. It's unclear what sealant material goes in the groove and how well it holds up over time vs. a theoretically-perfect silk thread job. We also wonder what the implications are if one needs future engine work that requires the crankcase to be split, by a shop that's not Ly-Con. If anyone here has direct experience with any of these options, I'd love to hear about it. In the spirit of Mooneyspace, rampant speculation is also welcome, of course. Unless you have an engine with roller tappets, which sounds like you don’t since it hasn’t been OH in 35 years, why wouldn’t you do dlc coated lifters? They have been around a good long time now and seem to help the cam spalling issue.
Vance Harral Posted November 13 Author Report Posted November 13 12 minutes ago, Slick Nick said: Where’s it leaking oil from We're not overhauling just because of the oil leaks, the very long calendar time in service is also a factor (35 years!) But specifically regarding oil, a better question would be where it's not leaking oil. This engine leaks oil from at least the crankcase seam, the oil pan, a couple of case half through bolts, one rocker cover, several pushrod tubes, every cylinder head drainback tube, the crankshaft main seal, and the prop governor seal on the accessory case. Every one of the known leaks has been previously addressed with the least invasive fix (generally replacing seals that are easily accessible and tightening bolts/clamps for those that are not) - in some cases multiple times - but all have returned. Although total oil consumption is nominal, it now blows oil from so many places during normal operations that it's essentially impossible to identify every leak, even with all the usual tricks: baby powder, fluorescent dye, etc. More importantly, even if we knew all the sources, truly fixing all of them would require a degree of engine and exhaust system disassembly that would be very likely to create other, more severe maintenance-induced failures, the repair of which would be money down the drain vs. an inevitable overhaul. Believe me, I'm the first to advocate for overhaul on condition rather than calendar time or time in service. But everything has it's practical and emotional limit. 3
Vance Harral Posted November 13 Author Report Posted November 13 3 minutes ago, Ragsf15e said: why wouldn’t you do dlc coated lifters? Because they cost more and we're not yet convinced they do anything specifically helpful for our use case. Willing to be convinced they're worth it, though, at least in resale value. 14 minutes ago, Ragsf15e said: They have been around a good long time now and seem to help the cam spalling issue. I'm aware DLC technology has been developed for decades, but the earliest mention I can find of its use in Lycoming engines is 2021, just a few years ago. Not very comforting from a, "we didn't realize they would cause such-and-such problem" perspective. Again, the current engine has delivered good service (with regular use in a dry climate) for 35 years. so it's not like short-life cam spalling in Lycomings is inevitable. If you're convinced DLC lifters are worth it, make a case - I'm all ears. But I need something stronger than, "they seem to help". 1
KSMooniac Posted November 13 Report Posted November 13 I wouldn't bet any modern engine parts will perform as well/last as long as your old stuff, even in a dry climate. Acknowledging that, I would go for DLC lifters and the firewall forward centrilube cam mod in addition to all of the options you already mentioned. Porting and polishing might not net noticeable power increases, but they can flow-match the cylinders so you get even power output from each, and thus a smoother engine. You can also get the lifters flow matched for bleed and that helps as well. Dynamic balancing of all the rotating mass and matching all pistons is vital for a smooth engine. They'll do it to a much tighter tolerance than Lycoming. All of that is beneficial for vibration reduction, increased comfort, reduced chance of case and exhaust cracking, etc. Sent from my motorola edge plus 2023 using Tapatalk 1
Ragsf15e Posted November 13 Report Posted November 13 51 minutes ago, Vance Harral said: Because they cost more and we're not yet convinced they do anything specifically helpful for our use case. Willing to be convinced they're worth it, though, at least in resale value. I'm aware DLC technology has been developed for decades, but the earliest mention I can find of its use in Lycoming engines is 2021, just a few years ago. Not very comforting from a, "we didn't realize they would cause such-and-such problem" perspective. Again, the current engine has delivered good service (with regular use in a dry climate) for 35 years. so it's not like short-life cam spalling in Lycomings is inevitable. If you're convinced DLC lifters are worth it, make a case - I'm all ears. But I need something stronger than, "they seem to help". I can’t make that case, but I also live in a pretty dry place and I was planning to either get a factory reman (roller lifters) A1A or get dlc coated lifters if a factory reman wasn’t possible. Of course many engines had lasted a long time - yours, my A1A was 24 years/60000tt, 1500 soh when i sold it. However, I would personally prefer one of the two “fixes” even though my cam hadn’t been destroyed. How much extra does the dlc cost?
jetdriven Posted November 13 Report Posted November 13 We sent the whole top end of our engine off to Ly-con to have it ported and Cryo treated and everything else they would offer for those, its probably 2kt. faster. 5-8hp perhaps. We did also have the Alodine cylinder heads with a black barrels, and we painted the black barrels ourselves of Cerakote. 3
MB65E Posted November 13 Report Posted November 13 I’ve sent 7 engines I think to Kenny. Awesome experiences each time. Metals change, older metals prior to 96 productions I feel were better than what Lycoming produced later on. Overhauling everything you can VS factory new parts is a way to keep the reliability. I really like the Alodined on all of the aluminum parts with the black barrels. This basically eliminates the flaking paint from lycoming issues. I painted my barrels, pushrods housings and Valve covers. Everything else is a goldish alodined. Great time to remove the engine mount and re-finish it too. I would do the DCL on any component offered. Amazing technology. As far as the oring on the case, I think it’s a great idea, but time will tell if the silk and Permatex vs the o-ring is better. I would race balance all rotating components along with porting and polishing. The cylinders will be better than Book values by far this way. Your wait time really depends on how many new parts you actually need. He can do most work in house, vs sending everything to Oklahoma. I would expect a new cam shaft, Rods, rod bolts, a rotating gear or two, Exhaust valves, new hoses and mags. But keep the bendix mags if you have them and overhaul them. Send it and let them work their magic! -Matt
EricJ Posted November 13 Report Posted November 13 12 hours ago, Vance Harral said: Our partnership voted this week to order an overhaul exchange IO-360-A1A from Ly-Con (lead time is currently advertised as 8 months, though we're fully prepared for it to be much longer). The current engine is actually running fine - good compressions, oil analysis, and borescope. But it leaks an embarrassing amount of oil from various nooks and crannies, the long lead times on engines change the "run it till it breaks" logic a bit, and after almost 35 years and 2600 hours we just feel like it's time. The purpose of this thread is to pick the brains of the well-educated folks here about options Ly-Con offers on an IO-360 overhaul. The floor is open for opinions on: FACTORY NEW LYCOMING CYLINDERS: We're inclined to do this, but even if we weren't, I don't actually think it's an "option". It's my understanding that at this time and for the foreseeable future, there is a dearth of donor angle-valve cylinders, such that you're going to need new ones unless you actually send in your own engine and wait months/years for the shop to overhaul the cylinders you send. PORT FLOW & BALANCE CYLINDERS: We understand the premise, but speculate the result is a tiny horsepower difference that is only meaningful if you're trying to win a race. STRIP PAINT FROM CYLINDERS, PAINT BARRELS BLACK, ALODINE HEADS FOR IMPROVED COOLING: Undoubtedly looks sharp on delivery, but we're very skeptical it makes any difference in cooling, and worry how the appearance will hold up over time. SPECIAL COATINGS ON PISTONS, VALVES, AND SPRINGS, DLC COATED ROCKER SHAFTS AND PISTON PINS: these are relatively inexpensive options that seem likely to reduce the risk of corrosion and wear. But the airplane lives in a dry climate, and the last engine has lasted decades without them. It's unclear to us if these "new" coatings have been around long enough in aircraft piston engines to feel confident they don't have some not-yet-discovered vulnerability that makes the cure worse than the disease. LY-CON CRANKCASE O-RING MODIFICATION STC SE001954SE: this STC modifies the crankcase halves to machine a groove which holds a sealant ring at assembly, rather than using the traditional silk thread. It's the most interesting option to us, and the subject of much discussion. We're all about anything that reduces oil leaks, having been irritated by them for decades, and this method seems to require less in the way of "magic hands" to get right. But this is a one-way modification, you can't go back to silk thread once it's done. It's unclear what sealant material goes in the groove and how well it holds up over time vs. a theoretically-perfect silk thread job. We also wonder what the implications are if one needs future engine work that requires the crankcase to be split, by a shop that's not Ly-Con. If anyone here has direct experience with any of these options, I'd love to hear about it. In the spirit of Mooneyspace, rampant speculation is also welcome, of course. My motor is currently at the overhaul shop getting redone, and they indicated that Lycoming has been making noises about doing a run of IO-360 cylinders, but don't hold your breath. I'd +1 that there doesn't seem to be any downside to DLC on the valve tappets, and it does reduce risk of future issues with the cam. The shop that has my motor says that they always do DLC on tappets now since it reduces the likelihood of a warranty claim, so it's not even an option to *not* get DLC on tappets. There's already a Lycoming-approved alternative to the silk thread, which is the use of particular sealant types that apparently work as well. That might be something to investigate rather than the STC. FWIW, I wouldn't personally trust a huge run of o-ring material in the long run over a silk thread or other approved alternative. The o-ring material won't be servicable, so when (not if) it leaks it's not any better than the existing methods. Also FWIW, proper silk-thread seals usually last the life of the overhaul. They're pretty much proven technology, which is why that technique has been used for so long. 3
Vance Harral Posted November 13 Author Report Posted November 13 Thanks for the opinions so far, much appreciated. Our quote shows about $2200 for all coating options, but you can break them out: $725 for DLC rocker shafts, $460 for DLC piston pins, and $997 for "special coatings on pistons, valves, and springs" (may or may not be DLC). DLC-coated lifters are actually included with the base price, which probably means they don't have any other kind in inventory. These are not large costs in the grand scheme of things, my hesitancy just stems from the fact that the tech still seems new in aircraft engines (I understand it's been used elsewhere for longer), and I've yet to see any A/B comparison data. It seems there is just an assumption that DLC must be worth it because "it's obvious", or "the technology is amazing", etc. I've worked my whole life in tech and have become unreasonably jaded about these sort of qualitative claims without any quantitative data. I feel like for every, "this technology is amazing" story, I know of a counterexample like Mobil 1 synthetic oil, GAMI 100LL, etc. But I don't mean to be overly cynical - the advocacy for DLC coatings are appreciated. 5-8hp from porting/polishing sounds plausible. That's about a 3% horsepower increase, which gives about 1% speed improvement and about a 2% climb improvement, Juice not worth the squeeze for us, I think. But the smoothness argument is interesting. I've never been in any 4-cylinder airplane which didn't feel like a rattle trap compared to 6-cylinder flavors, but maybe I just haven't been in one that's well balanced. The painted/alodined cylinders certainly look cool. I'm not aware of issues with the original paint flaking, can someone elaborate? 12 minutes ago, MB65E said: Overhauling everything you can VS factory new parts is a way to keep the reliability. Yes, but this dramatically increases downtime, which we've decided is a factor for us and we've decided is worth the extra cost and the (vague) risk. I'm aware of the issues with crankshafts from the 1990s, but so many components are replaced even when you send in your own engine that it seems like a crapshoot either way. 1
Rick Junkin Posted November 13 Report Posted November 13 1 hour ago, Vance Harral said: 5-8hp from porting/polishing sounds plausible. That's about a 3% horsepower increase, which gives about 1% speed improvement and about a 2% climb improvement, Juice not worth the squeeze for us, I think. But the smoothness argument is interesting. I've never been in any 4-cylinder airplane which didn't feel like a rattle trap compared to 6-cylinder flavors, but maybe I just haven't been in one that's well balanced. My cylinders were ported and balanced by Lycon before I bought the airplane. Anecdotally the airplane has TKS, which typically induces a speed penalty, but it still makes book speeds with slightly lower fuel flows (tenths of GPH). And I'm able to run LOP without vibration (TIO-540-AF1B) which again anecdotally could be aided by the cylinder balancing. Not a "smoking gun" endorsement but a positive performance report. 3
MooneyMitch Posted November 13 Report Posted November 13 2 hours ago, jetdriven said: We sent the whole top end of our engine off to Ly-con to have it ported and Cryo treated and everything else they would offer for those, its probably 2kt. faster. 5-8hp perhaps. We did also have the Alodine cylinder heads with a black barrels, and we painted the black barrels ourselves of Cerakote. I see some dust on your spinner....................you might want to take care of that!!
MikeOH Posted November 13 Report Posted November 13 13 hours ago, KSMooniac said: You can also get the lifters flow matched for bleed and that helps as well. Since hydraulic lifters take up valve lash, I'm not following how matching their 'bleed' helps. Please elaborate.
KSMooniac Posted November 13 Report Posted November 13 17 minutes ago, MikeOH said: Since hydraulic lifters take up valve lash, I'm not following how matching their 'bleed' helps. Please elaborate. It was explained to me that variable hydraulic performance leads to minor variations in valve opening/closing and that affects power output as a second-order effect. Matching all of them to a tighter tolerance band would help smooth everything out, and I was after extreme balance and smoothness when doing my overhaul so I opted to go for that extra service. I might've gotten up-sold, but IIRC it wasn't much money. I think just a little bit of time to measure and sort from inventory vs. a machining operation. Vance, after all of my effort on balancing, flow-matching, etc. and a dynamic prop balance after break-in, I got to 0.01 IPS and my engine and prop feel like a sewing machine. The effort is worth it! You're likely just used to your shaky installation and don't know what you're missing. Even if you don't enjoy a smoother ride, minimizing the chances of a case crack should be enough motivation to take every precaution now to avoid downtime and expense later. 1
MikeOH Posted November 13 Report Posted November 13 As someone with a high-time (2700+ hours) IO-360A1A in my 1970 F model, I'm VERY interested in your decisions and upcoming experiences! My thoughts, absent any information beyond this thread: 1) I'd get NEW cylinders if at all possible. I think there's some truth to how many hours/time you can OH a cylinder. Plus I've fought high temps on my #2 cylinder and have tried EVERYTHING including having Ly-Con overhaul it. I'd love to start with fresh cylinders. But, as you say, it just may not be possible to get angle valve cylinders these days. 2) I've had head work done on 'performance' auto engines, but I would NOT be inclined to bother unless the incremental cost is slight. Juice not worth the squeeze, IMHO. 3) I, too, am skeptical of real improvements in cooling with black barrels and alodine heads; is there any actual before/after data showing quantifiable temp decreases? Further, when I got my #2 cylinder back from LyCon the barrel was painted black and it still runs hot! I wouldn't bother. 4) I just can't imagine what the purpose of coatings on all the parts listed really would be! Both our engines have made it well past TBO and I seriously doubt 'improving' the friction/wear on those parts is going to help. Without out data, it seems like expensive snake oil. Having said that, I would get the DLC lifters even though I've always believed the cam wear issue was due to poor camshaft metallurgy out of Lycoming for some period of time. Frankly, getting a 'new' camshaft with the rebuild still scares me. I'd prefer mine to just be reground, but then I'd worry there wasn't much left of the case hardening! 5) If you are worried about the lack of field time/experience for the DLC/coatings, this crankcase seal STC should really scare you! Maybe I'm biased as my high-time engine really doesn't leak oil but I'd take my chances with the proven silk thread. Maybe use the newer sealant as that doesn't seem too risky and won't be an issue if the case ever needs to be split. 1
Jsno Posted November 13 Report Posted November 13 I have overhauled a few lycomings myself since I have an A&P. If you are leaking at the case, you probably have fretting between the case halves. That will cause the cylinder nuts to lose torque. Not good. I tried and like nickel cylinders as they break in less than 45 minutes and will never pit. I have not tried the DLC plated lifters but sounds interesting. I would not waste the money on the rocker shafts as I have always just have aircraft specialties regrind them and had no problems. I guess it depends on how much money you want to spend but some of what you have talked about seems like overkill. Better to use the money for gas. I think the most important thing that I have found is to : 1 Overhaul or replace all accessories. 2. Do a proper engine break in. 3. Use an engine dryer to prevent moisture on the camshaft as even in warm climates, the engine produces one gallon of water for every five gallons of gas burned. You want to keep that off of the steel parts. That will even kill an Arizona camshaft. I also use a Twin Hornet to keep the upper end warm to prevent condensation. 4. Fly often for at least a half hour to keep everything dry and lubed. 5. Keep your overhaul simple. Folks will sell you all kind of stuff to make money but remember you got well over 2000 hours on a standard engine. Just my thoughts on it. 5 1
jetdriven Posted November 14 Report Posted November 14 7 hours ago, Paul Thomas said: @jetdriven What air filter do you have? Donaldson 2
jetdriven Posted November 14 Report Posted November 14 21 hours ago, Ragsf15e said: I can’t make that case, but I also live in a pretty dry place and I was planning to either get a factory reman (roller lifters) A1A or get dlc coated lifters if a factory reman wasn’t possible. Of course many engines had lasted a long time - yours, my A1A was 24 years/60000tt, 1500 soh when i sold it. However, I would personally prefer one of the two “fixes” even though my cam hadn’t been destroyed. How much extra does the dlc cost? DLC coating has come on all Lycoming engine lifters that they ship now, as far as I know 1 1
JoeM Posted November 14 Report Posted November 14 We just overhauled the io360 A1A on our E model. Neither Overhauled nor Lycoming cylinders were available. The choice was OH Chrome or new from Continental. I know that sounds weird, but Continental bought a company that makes cylinders, and they now make them for Lycs. Expensive but available. I didn't want Chrome. We also bought a new cam and DCL coated lifters. J&J Airparts was great. Our original cylinders are waiting for oversized pistons (backordered of course) so we will use those on another engine we are getting ready to OH. 2
Jsno Posted November 17 Report Posted November 17 On 11/13/2025 at 9:47 PM, JoeM said: We just overhauled the io360 A1A on our E model. Neither Overhauled nor Lycoming cylinders were available. The choice was OH Chrome or new from Continental. I know that sounds weird, but Continental bought a company that makes cylinders, and they now make them for Lycs. Expensive but available. I didn't want Chrome. We also bought a new cam and DCL coated lifters. J&J Airparts was great. Our original cylinders are waiting for oversized pistons (backordered of course) so we will use those on another engine we are getting ready to OH. I bought a set of overhauled cylinders with Nickel plating from J&J. Installed the valves myself. They broke in in less than an hour and no issues with pitting in the future. This is the second engine that I have put Nickel cylinders on and I am a believer.
Greg Ellis Posted November 17 Report Posted November 17 What are the pros and cons of nickel cylinders besides being broken in ridiculously fast?
jetdriven Posted Tuesday at 02:18 PM Report Posted Tuesday at 02:18 PM They often don’t seat properly and then they use a lot of oil and they run hot. And then often times, by the time you get to 1500 hours or even 1000 hours, they polish iut smooth and start to use even more oil so I’m not so convinced they’re a good fit for Mooney especially. The ones selling chrome and nickel plating. Options are the ones who were taking cylinders worn out past standard boar and then re-roaming them or nickel, plating them back down to standard size. But that sounds like a solution looking for a problem. It may not be the solution you’re looking for. 1 2
GeeBee Posted Tuesday at 03:27 PM Report Posted Tuesday at 03:27 PM I had an O-320B2B (160 hp) ported and polished by Gann along with the case seal, main dowels etc. The thing was a monster. It turned 173 on the dyno and ran like a top. Look, it takes a lot of power to increase speed as it is a square function but rate of climb is directly related. Having a 10% increase in rate of climb is not insignificant.
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