Lifter Failure

What is the relationship between lifters and coked valve guides?
 
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James331 said:
Sometimes lifters do fail

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Is that Nancy Kerrigan?
 
A crude hardness test could be done with a sharply pointed object (like a plumb bob) with a specific amount of weight applied to it for a specific amount of time and compare resultant indentations of two samples, the suspect one and a known good one.
 
nrpetersen said:
A simple test would be to compare the response to a small 3 corner file comparing a good (worn is OK) old lifter to a questionable one. I suspect the lifters should be close to Rc 60 which is close to file-hard.

It isn't a proof positive test by any means but it is one that can be done easily.
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When they meet the design, and the design was wrong, What then?
 
bnt83 said:
Its interesting to me that there are 10 year old engines with worn out cams & lifters and you can find blogs about engines over 50 years old and finally being torn down for the first overhaul since it was new and the cam & lifters don't look bad at all.
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It's a matter of design, the high horse power engines typically want the valve to open quicker stay open longer and close quicker. this makes for steep cam lobe ramps and is very hard on lifters, this is why we need roller lifters.
Roller lifters are expensive to build, and require new certification which the manufacturers don't want to pay for.
 
GlennAB1 said:
A crude hardness test could be done with a sharply pointed object (like a plumb bob) with a specific amount of weight applied to it for a specific amount of time and compare resultant indentations of two samples, the suspect one and a known good one.
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Why not simply remove a lifter and run the Rockwell hardness tester routine.
 
nrpetersen said:
"Corrosion rates are a function of temperature. Warmer = more corrosion.

Humidity outside the engine is a factor for long term storage, but short term, there is more than enough water inside to keep the humidity high until it has a chance to diffuse through that long vent tube (I don't have any real number for that, but I would suspect days to weeks - not minutes or hours."

Corrosion rate doubles about every 18 degF you raise the temperature.

Theoretically the crankcase is full of steam and CO2 on shutdown. The steam condenses on the engine's cooling surfaces to make water. There's probably not much escaping thru the breather. That sort of thing is only done in modern automobile engines via the positive crankcase ventilation system which sucks crankcase gases into the combustion chamber & exits it thru the exhaust.
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Within 2 hours any water like you have suggested will have condensed and migrated to the bottom of the oil sump and stay there until reheated and returned to steam.
All engines we see will protect them selves by varnishing up the entire interior. the only place the corrosion will occur will be the wear tracts where we have rubbing of one part to another. (right where we don't want it)
 
Checkout_my_Six said:
In this case....I'd want old parts vs. new. Once the parts have proven themselves and out of the infant mortality zone....I want them. In this case the lifters failed in the infant zone (less than a few hundred hours). Parts surviving hundreds of hours....are proven.

So long as they are dimensionally acceptable with hundreds of time proven operation they are more desirable IMHO.
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Most aren't. the norm is to re-grind, due to the cost of new. the problem lies in how many times can we regrind?
 
GlennAB1 said:
Nope, but Arrow67 mentioned coked valve guides, another symptom of possible hydrogen embritalment.
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Although, "Aircraft Powerplants" by Bent/McKinley states that coking in turbocharged engines can be caused by incorrect lubricant. But I'd think it would have been more prevalent in the turbocharger.
 
Tom-D said:
Most aren't. the norm is to re-grind, due to the cost of new. the problem lies in how many times can we regrind?
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My apologies for the noob question-when these parts (cam, lifters) are re-ground and used in the overhauled engine, do they get re-hardened or is the grinding done lightly enough to preserve the original hardened layer? Along similar lines, are these like flat tappet lifters in a car, where they wear unique to the lobe they were used with?

Sorry for the noob stuff, I am quite familiar with Chevy V-8's from my muscle car days before flying, but some of the aircraft engine particulars are still new to me.
 
Omalley1537 said:
My apologies for the noob question-when these parts (cam, lifters) are re-ground and used in the overhauled engine, do they get re-hardened or is the grinding done lightly enough to preserve the original hardened layer? Along similar lines, are these like flat tappet lifters in a car, where they wear unique to the lobe they were used with?

Sorry for the noob stuff, I am quite familiar with Chevy V-8's from my muscle car days before flying, but some of the aircraft engine particulars are still new to me.
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This question should be directed to the machine shops that do the re-work procedures. I don't know if all shops do, but I do know the shops I use do.
Every 0-200 and 0-300 that I rebuild ( the only rebuilds I do) have the cases cleaned, inspected, lapped and line bored the cranks are reground as required and renitrided, (or new) the lifters are new, hydraulic units are new, cylinders are new, That is the minimum, the accessories are the owners option.
 

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Looking at the images only 2 possibilities. Lubrication or metallurgy, What oil are you using?
 
Arrow67 said:
A friend of mine has a cessna t210 with a ram engine upgrade. Engine installed 2 years ago, has 270 hours on it. He takes care of it meticulously. Any squawks fixed right away, heated hanger, oil changed every 25-30 hours with 100w plus and camgard. Never sits more than 2 weeks at a time. Last oil change metal was found in the filter. Teardown found 8 out of 12 lifters falling apart. Cam wasn't too bad, but needs to be replaced. Crank looks good, oil pump housing torn up. The shop claims rust is the culprit. I say BS. Anyone else have opinions on this?
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The lifter nearest the camera, shows Electrolysis, the one farthest away show what happens when a lifter that has had electrolysis and continued to operate until it ate the cam and lifter.
I see this a lot in the engines I salvage. they have sat long periods, but this can happen in shorter times.
 

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Tom's "lifter spauling. jpg" is probably what our suspect lifter looked like had it been caught sooner. After the case hardening had worn through it left the base metal vulnerable to corrosion.
 
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Sorry to bring back an old thread, but might have an answer to the problem. My friend with the 210 brought his plane in to another shop for an oil change, just because of convenience. The mechanic said something to my friend about the plane taking a lot more oil than indicated on the dipstick.(like 3 quarts). Our thoughts on the previous failures are that the dipstick may be wrong, the oil is contacting the crank and becoming aerated.
 
I am a new aircraft owner and like most owners, I really want to take care of my engine with “best methods” approach. What is the most recent conclusion of the brain trust on engine dehumidifiers? Any chance a dehumidifier would mitigate or even eliminate this type issue?
 
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