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Auto plug adapters...forever?

AAflyer

Well Known Member
I'm in the process of removing my engine for a crankshaft replacement, and intend to R & R those things that are "usually" replaced around 500 hours. ( I have 381 hours on my Superior IO-360)
I know new copper gaskets are recommended, but how long do the adapters last? Mine, obviously, don't look new anymore, but seem fit.
Thanks,
 
I'm guilty of not following my own advice but I plan to fix that shortly...

Having a spare set of adapters on hand means that when you do the IRAN you will actually be able to replace as necessary, immediately, rather than risking being grounded for lack of this part.

I'm considering ordering one spare to keep in my fly-away kit as well.
 
When I ordered my set of adapters, the seller actually questioned why I'd be ordering 5 instead of 4 or 6. I wanted a spare. Of course in my world, the biggest challenge will be *finding* the spare if I ever need it! :)
 
Auto plug adapters...forever?

mmmh, yes, why not? Are u afraid they gonna wear out, how? Any reports of cracked adapters? Any other failure?
Well, more than 1K hours on mine, and surprise surprise they still do work :)
 
I've had Pmags for 650 hours and still running on the original adapters. Has anyone every had to replace an adapter? What would typically make an adapter unfit for continued usage?
 
On a different thread someone suggested using Denso (5000) L14-U Traditional Spark Plug. No adapter needed. Has anyone done this? Are there downsides to using plugs without adapters?
 
When I ordered my set of adapters, the seller actually questioned why I'd be ordering 5 instead of 4 or 6. I wanted a spare. Of course in my world, the biggest challenge will be *finding* the spare if I ever need it! :)

Where did you purchase individual adapters?
 
How do you determine when a spark plug adapter needs to be replaced? What's it's mode of failure, what are the symptoms, and what are the consequences?
 
I'm in the process of removing my engine for a crankshaft replacement, and intend to R & R those things that are "usually" replaced around 500 hours. ( I have 381 hours on my Superior IO-360)
I know new copper gaskets are recommended, but how long do the adapters last? Mine, obviously, don't look new anymore, but seem fit.
Thanks,

Best I know, adapters should last the life of the engine or more.

Copper plug gaskets are different. They are replaced because copper work hardens. The harder gasket may not seal as well when used the second time, unless annealed. Annealing them is easy. Hang a bunch on a piece of steel rod. Heat them to glowing red with a torch. Throw them in a bucket of water. They are now nice and soft. Although not strictly necessary, I string a bunch of them on a wire and lightly bead blast so they look nice and are obviously ready to go when I dig them out of a drawer a year later.
 
I have replaced all 4 auto plug adapters on my engine before (4 bottom plugs)... I'm more of the live and learn type. The way I see it, the cost of the adapters is the cost of my schooling and education.

I replace my plugs every 50 hour oil change, 10 times in the last 4.5 years. Lots of in and out of my adapters (EMag brand). Throw a dab of anti-seize on the threads before I put the assembly into the Cylinder (following EMag installation instructions/procedures). Every time I remove the adapters, I noticed some "crud" left in the threads due to the anti-seize. So... I cleaned the threads with a wire brush, re-install per the instructions, and carry on. After about 7 cycles of this, I have noticed some erosion on the threads of the adapter. Best described as the OD threads of the adapter are becoming tapered. My only guess is that over time, any air gap between the OD threads of the adapter and the cylinder allows combustion gases to play around and erode the adapter. AND/OR, my brass wire brushing habits were too aggressive to clean the threads. Either way, I was getting less and less threaded surface area to engage with the cylinder head. The adapter would still seat and torque alright, but I imagine there was a small air gap forming inside between the cylinder and the adapter allowing for progressively more combustion gases to erode the brass. Maybe... Just a theory.

I ended up replacing 4 of my 8 adapters. I figure, it's a cheap enough consumable that I don't have to worry about it when I'd rather be out flying than tinkering (most days).
 
After just having to extract a broken one, I'd advocate for a 400 hr life limit. I had one break at ~~500 hrs. I know these aren't cheap, but trust me, you don't want to have to deal with this.
 
My adapters have been removed once, due to ECI cylinder recall.

My question..... why are you removing the adapters??

If you are not removing your adapters with your plugs, what problems are you having with your adapters??
 
I had one break at ~~500 hrs

Cool. Now could you please enlighten the readership as to how it broke? Why did it break? Define Broke?
Checking, eventually gapping auto plugs every 100hrs is plenty enough. So you remove the plugs and leave the adapters in place, now what?
 
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My adapters have been removed once, due to ECI cylinder recall.

My question..... why are you removing the adapters??

If you are not removing your adapters with your plugs, what problems are you having with your adapters??

Most people including myself seem to get the adapters with spark plugs upon removal. I wish they would stay in the cylinders but never happens. haha
 
My adapters have been removed once, due to ECI cylinder recall.

My question..... why are you removing the adapters??
...

I don't have a 14mm adapter for my compression tester (yet). Thanks for the reminder!
 
Most people including myself seem to get the adapters with spark plugs upon removal. I wish they would stay in the cylinders but never happens. haha

With plugs torqued to 22 ft-lbs and adapters torqued to 35?
 
Most people including myself seem to get the adapters with spark plugs upon removal. I wish they would stay in the cylinders but never happens. haha

If the adapter is installed with a higher torque than the plug, it should stay in as the plug is removed. I have NEVER had an adapter come out with the plug, except when I wanted it to. I broke the torque of the plug, then changed sockets and removed the adapter with the plug. Only did that once.

Note..... I installed my adapters IAW Lightspeed Eng. early instructions. They have served me well, and I will continue to do it the same way.
 
With plugs torqued to 22 ft-lbs and adapters torqued to 35?

Yep - same here, with a calibrated torque wrench and done as per spec - I still get about half of the adapters out with the plug.
 
Annealing them is easy. Hang a bunch on a piece of steel rod. Heat them to glowing red with a torch. Throw them in a bucket of water. They are now nice and soft.

The reality is that one doesn't need to throw the heated copper into water. Air quenching is plenty good enough.

I had an opportunity to read a treatise written by a PhD metallurgist who is also a Bonzi tree fanatic (I'll be darned if I can find the web reference to that document now!). The Bonzi folks use copper wire to "train" the branches of the tiny trees they are shaping. Flexing the wire hardens it a specific amount, thus by specifically flexing a wire to a known hardness the Bonzi grower can control how radically a tree branch, when laced to a copper wire, will be bent. Who would have thunk it!?!

This knowledgeable gentleman provided well-cited research which indicated pure copper (or reasonably pure copper) would remain in its annealed state until a quenching rate of about 1 million degrees per second was achieved.

In short, air or water quenching makes no difference to pure copper as both are a long way from a million degrees per second. I let mine cool off in the air and they are indeed soft after this process.
 
With plugs torqued to 22 ft-lbs and adapters torqued to 35?

I have never done it because the E-mag manual specifically mentions not to do this. They only want the assembly torqued by the spark plug to 18 ft/lbs.

I believe the Lightspeeds specify the 22 then 35 method (if memory serves) but E-mag for some reason warns against it.
 
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If you’re using SDS adapters, their instructions are a variation from the others and call for inserting the plug into the adapter using a thin stripe of anti-seize on both sets of threads (I use graphite spark plug anti-seize from ACS and avoid the first 3 threads out of habit), then torquing the plug to 19 ft-lbs, and then the adapter to 25 ft-lbs (versus 35 ft-lbs in the lycoming service instruction, which I suspect is due to the softer metal aspect).

The question comes down to who’s adapters you’re using, which should dictate which method to use. Either way, I agree with having a spare adapter.
 
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FYI. Lycoming says not to use a graphite-based anti-seize on spark plugs.

Ref: Service Instruction No. 1042AH, "Approved Spark Plugs":
From page 2:

"Spark Plug Installation Guidelines
1. ...
2. ...
3. Use a copper-based anti-seize compound or engine oil on spark plug threads starting two full threads from the electrode, but DO NOT use a graphite-based compound.
4. ..."​

As a side note, I have one LSE Plasma III ignition system on my RV-8 and the spark plug adapters have never come out when removing the auto plugs. About 900 hours on the system with no issues.

True, but both Tempest and Champion sell a nice little bottle of dark grey, slippery anti-seize that works great for plugs. Technically, it's a "proprietary" product... The key is to not put it near the tip of the spark plug where it could foul the tip, hence my tip about leaving the first three threads clear.

Ironically, the SI you referenced discusses using “Approved Spark Plugs”, which I doubt you’re using with the adapters of the topic.

The same fouling is true for any anti-sieze. Been using it for decades with no issue.
 
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Let's not be too sensitive about an old debate, Lycoming (copper) vs Champion (graphite).

Given copper anti-seize is also highly conductive, I doubt there is concern for the electrical conductivity of graphite.

I suspect Lycoming's preference is due to thermal conductivity. I say suspect because I don't know the actual coefficient of thermal conductivity for grease containing copper and graphite grains. If we look only at published data for copper and graphite at 125C, the copper is about twice as high.
 
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Threads

Don't forget there is about 60% more thread area on the plug then there is on the adaptor. The adaptor needs more torque then the plug to offset the difference.
 
I haven't used anti-seize of any kind on plugs for years on any of the airplanes I maintain. The helicoils are stainless and its simply not necessary. This makes plug changes and compression checks easy.
 
Cool. Now could you please enlighten the readership as to how it broke? Why did it break? Define Broke?
Checking, eventually gapping auto plugs every 100hrs is plenty enough. So you remove the plugs and leave the adapters in place, now what?
It broke in about the only way probable. It twisted off with plug removal leaving most of the threaded portion in the cylinder head. I use nickel based never seize on adapters and plugs every time they're removed. As per Rocket Bob, I might try going dry.... 90% of the time, they come out with the plug. So I clean and reinstall with each set of new plugs replaced generally at annual inspection. Looking at the failed adapter, it appeared embrittled and pitted. Guessing a corrosion mechanism. Hence a suggestion to consider making them life limited.

There's a cheap supplier in the UK, and I'd guess they ship to the US:

https://www.gsparkplug.com/1x-spark-plug-thread-adaptors-18mm-down-to-14mm-brass-m14-m18.html

I followed the link and it took me to their "US Store." Much nicer price, thanks!! I'll definitely keep this in mind.
 
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Ok, thanks for clearing things up Bryan. I had difficulties imagining of one of these adapter could "break". Of course having the thread come off and eventually also damaging the cylinder head is highly undesirable.

I remove my spark plugs every 100h, and, despite having used a higher torque than published and no anti-seize, one or two will usually come off with the spark plug :(

Which has me wondering about the quality of the different adapters, cheap ain't a synonym of good. Most of them seem to be made outta "brass"... maybe steel would be better?
 
It broke in about the only way probable. It twisted off with plug removal leaving most of the threaded portion in the cylinder head. I use nickel based never seize on adapters and plugs every time they're removed. As per Rocket Bob, I might try going dry.... 90% of the time, they come out with the plug. So I clean and reinstall with each set of new plugs replaced generally at annual inspection. Looking at the failed adapter, it appeared embrittled and pitted. Guessing a corrosion mechanism. Hence a suggestion to consider making them life limited.

On the galvanic table, aluminum is #1, steel is #3, and brass is #9. Place brass next to aluminum with a low torque setting to allow combustion gasses to penetrate the space and you may have a location for electrolysis.

It looks like steel adapters would be a better choice. My adapters from Lightspeed years ago are steel. I have never had one come out with the plug.
When it came time to move the adapters to new heads, they came out with no problem, and looked like new.
 
On the galvanic table, aluminum is #1, steel is #3, and brass is #9. Place brass next to aluminum with a low torque setting to allow combustion gasses to penetrate the space and you may have a location for electrolysis.

It looks like steel adapters would be a better choice. My adapters from Lightspeed years ago are steel. I have never had one come out with the plug.
When it came time to move the adapters to new heads, they came out with no problem, and looked like new.
But you'd need an electrolyte for galvanic or electrolytic corrosion, yes? Should be zero back on the bottom of no 3 cylinder, where this occurred.

I have no suggestion as to the exact type of attack that may have occurred, but the fracture faces and surrounding threaded areas looked more damaged than I'd have expected from an overtorque failure. And maybe it was a manufacturing defect. Regardless, steel might be the best direction for strength and potential corrosion concerns.
 
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looks like steel adapters would be a better choice. My adapters from Lightspeed years ago are steel.

Unfortunately, mine, 2003 vintage are not… any source for steel adapters?
 
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