Lycoming piston pin plug failure
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Continentals do suffer from the same problem.
We started to get aluminium in our 0-200 oil filter.
For ease we removed the engine and sent it to Richard Isenberg (top man and recommended by me).
If I remember rightly the cause was the pins comming loose in the gudgeon pin and a build up of air pressure due to heat forcing them hard against the cylinder walls.
Running sweet as a daisy ever since and that was quite a few years ago.
We started to get aluminium in our 0-200 oil filter.
For ease we removed the engine and sent it to Richard Isenberg (top man and recommended by me).
If I remember rightly the cause was the pins comming loose in the gudgeon pin and a build up of air pressure due to heat forcing them hard against the cylinder walls.
Running sweet as a daisy ever since and that was quite a few years ago.
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I to have talked to Richard Isenburg on this subject but he could offer no theory about the reason for the O-235 cylinder problems that are the root cause of the piston pin plug problems.
This along with the other problems is pointing me towards a lowering of engineering standards at Lycoming.
This along with the other problems is pointing me towards a lowering of engineering standards at Lycoming.
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Peter
My guess it that the O-235 cylinders are thinner that the others in the range and have a habit of warping, the result of this that a step gets worn at the bottom of the bore by the piston rings, this step bacon slices the piston pin plug.
Strange that Lycoming offer half the warranty on the O-235 cylinders that they offer on the rest of the range.
Strange that Lycoming offer half the warranty on the O-235 cylinders that they offer on the rest of the range.
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My guess it that the O-235 cylinders are thinner that the others in the range and have a habit of warping,
Either way, sounds like the design is NOT optimised for longevity and i'd suspect the short-runs/intermittent use nature of GA does it no favours either.
A piston-engine will do loads more if given long stretches at working-temperature. as opposed to "short hops" the cold-start cycle (especially if it's been stood a week and all the internal oil has drained down) causes a disproportionate amount of the wear.
my diagnosis:- poor design, inferior materials.....a good cash-generator for the spares sales business.
cynic?...What! Moi?
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Steve
The ridge is always at the bottom, not the top.
I am starting to think that You are correct about the quality of parts, thirty years back it was common for an O-235 to make TBO + 20% with a top end overhaul at half life.
The worst I have had is piston pin plugs at 290 hours and impending camshaft failure at 400 hours ( found at a shock load inspection).
Have Lycoming now found a very good income stream by producing poor quality parts ? I am not quite as cynical as you and think that the quality has gone down due to the pressure from the environmental legislation as some of the processes required are not very environmentally friendly. Add the pressure to keep costs down from the PMA parts suppliers and you have great pressure to go down market.
It has been demonstrated to me that Lycoming genuine parts no longer show any advantage over PMA items but are more expensive, I have run my business in the belief that quality is the best policy and I am more than happy to pay a premium for reliability but if I am not getting this reliability then Lycoming are driving me into the arms of the PMA market.
An own goal by Lycoming I think.
I am starting to think that You are correct about the quality of parts, thirty years back it was common for an O-235 to make TBO + 20% with a top end overhaul at half life.
The worst I have had is piston pin plugs at 290 hours and impending camshaft failure at 400 hours ( found at a shock load inspection).
Have Lycoming now found a very good income stream by producing poor quality parts ? I am not quite as cynical as you and think that the quality has gone down due to the pressure from the environmental legislation as some of the processes required are not very environmentally friendly. Add the pressure to keep costs down from the PMA parts suppliers and you have great pressure to go down market.
It has been demonstrated to me that Lycoming genuine parts no longer show any advantage over PMA items but are more expensive, I have run my business in the belief that quality is the best policy and I am more than happy to pay a premium for reliability but if I am not getting this reliability then Lycoming are driving me into the arms of the PMA market.
An own goal by Lycoming I think.
Last edited by A and C; 22nd Oct 2012 at 07:38.
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piston pin plug shaving Lycoming IO360
I am looking at an aircraft with this exact problem it is on the front two cylinders, which were replaced ~475 hours ago with genuine Lycoming cylinders. The cylinders replaced had ALSO exhibited the same problem after ~1075 hours. Those cylinders were Superior Millennium parts...
There is a theory that it may be exacerbated by excessive cooling on the front face of the front pots. I suspect it is some combination of inadequate lubrication, inadequately hardened cylinder wall and a dynamic which is forcing the plug against the cylinder wall, where it has no right to be.
It's very depressing that it has recurred on the replacement parts, where do you go from here?
Is North of barlu in the Pacific above Oz?
There is a theory that it may be exacerbated by excessive cooling on the front face of the front pots. I suspect it is some combination of inadequate lubrication, inadequately hardened cylinder wall and a dynamic which is forcing the plug against the cylinder wall, where it has no right to be.
It's very depressing that it has recurred on the replacement parts, where do you go from here?
Is North of barlu in the Pacific above Oz?
Last edited by neilmurg; 3rd Apr 2013 at 09:16. Reason: added question
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Differential Expasion
I was told forty years ago this problem is caused by not allowing sufficient time at low rpm before full power is set.
The aluminum piston expands losing contact with the pin allowing it to slide about in the piston. Some time later the pin warms up and tightens in the piston to one side causing cap wear.
The aluminum piston expands losing contact with the pin allowing it to slide about in the piston. Some time later the pin warms up and tightens in the piston to one side causing cap wear.
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Robin400
Three of my aircraft are based at a large airfield, it is just not posable to get the aircraft from the parking position to the runway without getting the engine warm enough for tale off.
I don't discount what you say but it is not relevant in my case.
I now base my business on Lycoming engines requiring overhaul at half TBO as this is all that the engines has demonstrated to me that they are able to achive.
I don't discount what you say but it is not relevant in my case.
I now base my business on Lycoming engines requiring overhaul at half TBO as this is all that the engines has demonstrated to me that they are able to achive.
I've seen this problem on O-235s fitted to C 152s. At the time we had several piston plugs "fail". Apparently there was never a problem with the O-235s fitted to the PA38. This led us down the path of wondering why a problem with the C152 but not the PA38, essentially same engine in both.
The PA38 never had an oil cooler fitted whereas the C152 did. Blanking of the oil cooler on the C152 cured the problem if I recall correctly.
The PA38 never had an oil cooler fitted whereas the C152 did. Blanking of the oil cooler on the C152 cured the problem if I recall correctly.
Last edited by 27/09; 4th Apr 2013 at 08:47.
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As I wrote in this thread a long time ago, this issue is not common in the USA (whose engine population is some 10x bigger) and appears to be due to "something" peculiar to UK engine rebuilding practices.
As I wrote in this thread a long time ago, this issue is not common in the USA (whose engine population is some 10x bigger) and appears to be due to "something" peculiar to UK engine rebuilding practices.
There have been problems outside of the UK and with rebuild shops that have many years experience. The problem started all of a sudden, I suspect there was a change in spec for the plugs or some related part which precipitated the problem.
Lycoming outsourced a lot of their parts manufacturing and as a result lost direct control of the QA process. Remember the issues with the crankshafts a while back.
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Peterh337
The first engine that had exhibited this problem was a Lycoming factory rebuild, the others were overhauled in the UK.
27/09
It is not a piston pin plug problem but one of cylinder becoming ridged at the lower end of the area swept by the piston rings, as the piston pin plugs pass over this step they have small chips removed this becomes very evident when the oil filter is cut open at maintenance checks.
The oil cooler thing mentioned above has a ring of truth about it as the lowest time engine that had this problem had it appear after just under 300 hours, the aircraft had been doing a lot of night training flights and the OAT was some times -15C or below.
The only positive thing to come out of this is that the customer support from the UK Lycoming agents has been very good, they too have suggested that this might be an over cooling problem.
27/09
It is not a piston pin plug problem but one of cylinder becoming ridged at the lower end of the area swept by the piston rings, as the piston pin plugs pass over this step they have small chips removed this becomes very evident when the oil filter is cut open at maintenance checks.
The oil cooler thing mentioned above has a ring of truth about it as the lowest time engine that had this problem had it appear after just under 300 hours, the aircraft had been doing a lot of night training flights and the OAT was some times -15C or below.
The only positive thing to come out of this is that the customer support from the UK Lycoming agents has been very good, they too have suggested that this might be an over cooling problem.
Last edited by A and C; 6th Apr 2013 at 13:35.
A and C Note I said piston plug or other related part, I was disputing overhaul techniques being the problem and suggesting a parts issue was the cause.
I agree probably not the piston plug, more likely the composition of the cylinders or the rings.
I'll bet the cylinders that had the lip causing the plug wear were the front two.
I agree probably not the piston plug, more likely the composition of the cylinders or the rings.
I'll bet the cylinders that had the lip causing the plug wear were the front two.
Last edited by 27/09; 6th Apr 2013 at 23:37.
