During Condition Inspection, had to install a new steel thread insert in #2 top spark plug, caused some shavings...

[Dandlac58]

I'm back to the Well-Spring of Knowledge on all things RV seeking guidance from the smart people on VansAF.

So, my IO-360 has two E-Mags. Love them. During Condition Inspection I decided to pull all the plugs and replace them. While pulling the top plug on #2 cylinder, I noted that part of the steel thread insert came out of the spark plug hole and as a result as I was pulling the plug and brass adapter the end of the steel thread insert was at such an angle that it literally shaved the external threads on the brass spark plug insert (NO KIDDING!). I did not notice this until it was mostly removed! I was able to vacuum out those shavings before completely removing the plug. I immediately got my A&P involved and he removed the offending steel thread insert and installed a new one. He ran his "re-threading tool", did a cursory blast of the cylinder with air pressure through the top spark plug hole and reinstalled the steel thread insert, the brass adapter, and the plugs and went home. However, for some reason I was concerned (perhaps the engine gawds had miraculously mind-melded with me) so I removed both plugs and when I inserted my borescope into the #2 cylinder through the top spark plug hole, I noticed a considerable amount of shavings sitting at the bottom of the cylinder near the bottom spark plug hole. I attribute those shavings to the A&P having to re-thread the spark plug hole before installing the new steel thread insert. So, long story short, I have spent considerable time (at least 3 hours sucking and blowing thru both the top and bottom spark plug openings to remove all those metal shavings. Looking in to the cylinder through both spark plug openings (with the borescope) it appears that I have removed most of the shavings if not all of them. I have not yet run the engine fearing I might damage the #2 cylinder.

I am seeking thoughts on whether I should remove the spark plug wires on all cylinders (so it cannot fire) and crank the engine through several cycles - with the upper and lower plugs removed from #2 - to see if I can blow out any remaining debris through the spark plug openings and the exhaust valve before I re-introduce combustion into that cylinder? Or does the #2 cylinder need to come completely off? Or some other option? Or am I making a mountain out of a molehill (of shavings). Not being an expert, I'm just trying to be extra careful before I restart the engine.

Thanks in advance for your thoughts (and yes, I am little "pissed" at my A&P - for not clearing the cylinder of the shavings but haven't yet addressed the issue with him...)

 

[sansoneservices]

Don't pull the cylinder. Flushing with a solvent and air blasting, maybe alternate solvent/air a couple of times. Kinda messy but you'll sleep better. Borescope as you've been doing. It will be ok

 

[rv8ch]

I am seeking thoughts on whether I should remove the spark plug wires on all cylinders (so it cannot fire) and crank the engine through several cycles - with the upper and lower plugs removed from #2 - to see if I can blow out any remaining debris through the spark plug openings and the exhaust valve before I re-introduce combustion into that cylinder?

I defer to those with a lot more experience than I have, but this is exactly what I would do, after doing what @sansoneservices recommended. It takes a few minutes to remove the other plugs. After a valve lapping session, it's recommended to use a long q-tip with some grease on it to pick up the little grains of abrasive material - that might also help. Probably overkill, but it does not take much time.

 

[lr172]

The shavings from threading are big enough that they shouldn't do any real damage and will eventually blow out the exhaust. Definately do your best to get them out, but doubt they will create any damage. It is the small stuff, like the abrasive mentioned above, that do the most damage.

 

[Bavafa]

Side tracking your main question which I think it has been answered by others, an easier way to crank the engine and wanting it not to fire/start is just to shut off power to the PMAG instate of unplugging the sparkplug, PMAG requires power for starting and without it, it can not start the engine. In fact EMAG doesn't recommend unplugging the sparkplug and have PMAG fires. If this method is used, sparkplug should be connected to the wire after removal and grounded so it fires.
On the main question, did your A&P grease the tapping tool to collect all the shavings? Maybe with both valves closed, blow air thru one sparkplug hole and vacuum thru the other hole.

Good luck

 

[storm_pilot]

Need to consider what type of material the shavings are made of. Brass from the adapters and aluminum from the head are both softer than the steel barrel and rings. Piston is aluminum and could be scratched in theory but my biggest concern would be clogging of the ring lands or ring gaps. That being said, if you have removed most of the material then I wouldn’t worry about it too much. Its fairly common to replace those threads with the procedure your mechanic employed.

 

[chaskuss]

Those shaving are either aluminum or carbon. Both are softer than the steel piston rings or the hardened steel cylinder walls. I would slowly rotate the engine till the piston of the affected cylinder is at top dead center, then try removing them again. Blow gun through the top plug hole should blow them out the bottom hole. Doubtful they would harm anything even if they had to exit via the exhaust system. FYI for next time. Rotate the engine to TDC on that cylinder BEFORE repairs. This can be done via borescope through a spark plug hole [make sure both valves are closed] or remove the valve cover, rotate engine by hand until both valves are closed and the TDC mark on the back of the ring gear lines up with the crankcase parting [seam] line. That will aid in removal of any foreign objects, particularly if you drop something steel in by accident.

 

[Dandlac58]

Don't pull the cylinder. Flushing with a solvent and air blasting, maybe alternate solvent/air a couple of times. Kinda messy but you'll sleep better. Borescope as you've been doing. It will be ok

Dear Sansoneservices,
Thank you for this re-assuring post. A couple of questions:
a. What kind of solvent to use? Am I to flood the cylinder - while it is in TDC position with the solvent? Should I inject through the top spark plug hole and then apply vacuum on the bottom spark plug hole?
b. Will injecting solvent in the cylinder get past the rings and down into the sump fouling my fresh oil in there.
c. The shavings definitely appear to be aluminum, they are "silvery shiney" and some of them look like a pigs tail (cork screw).
Much Appreciated.
Dan

 

[Dandlac58]

I defer to those with a lot more experience than I have, but this is exactly what I would do, after doing what @sansoneservices recommended. It takes a few minutes to remove the other plugs. After a valve lapping session, it's recommended to use a long q-tip with some grease on it to pick up the little grains of abrasive material - that might also help. Probably overkill, but it does not take much time.

Hi Mickey, I did attempt to drag a couple of large cotton swabs around the cylinder but was unable to get any of the shavings on the swabs. I've asked for some more info from Sansoneservices on how to flush the cylinder with solvent.

 

[Dandlac58]

The shavings from threading are big enough that they shouldn't do any real damage and will eventually blow out the exhaust. Definately do your best to get them out, but doubt they will create any damage. It is the small stuff, like the abrasive mentioned above, that do the most damage.

Hi LR,
I am 99.9% certain the shavings are aluminum from when A&P ran the thread tool. They are "silvery" visually with some being small specks and others being more like a pig tail, or a piece of a pigtail (cork screw looking). I can get a photo of them next time at the hangar (from those I caught in the vacuum canister). I think there are only a very few remaining in the cylinder. I am looking at irrigating the cylinder with solvent as sansoneservices advises as a final attempt to remove the last remaining shavings. Do you anticipate that what ever ones remain will be eviscerated during combustion and will just be blown out the exhaust valve?

 

[Dandlac58]

Side tracking your main question which I think it has been answered by others, an easier way to crank the engine and wanting it not to fire/start is just to shut off power to the PMAG instate of unplugging the sparkplug, PMAG requires power for starting and without it, it can not start the engine. In fact EMAG doesn't recommend unplugging the sparkplug and have PMAG fires. If this method is used, sparkplug should be connected to the wire after removal and grounded so it fires.
On the main question, did your A&P grease the tapping tool to collect all the shavings? Maybe with both valves closed, blow air thru one sparkplug hole and vacuum thru the other hole.

Good luck

Hi Bavafa,
Thank you for that info on the PMAG recommendation to not remove the wires from the plugs. I could simply pull the circuit breakers for both pmags and fully cut off fuel flow so the engine cannot start.
A&P did not grease the tool when he used it.
Yes, I absolutely blew pressurized air through the top hole while applying vacuum on the bottom hole and then vice versa.
Thanks,
Dan

 

[lr172]

Hi LR,
I am 99.9% certain the shavings are aluminum from when A&P ran the thread tool. They are "silvery" visually with some being small specks and others being more like a pig tail, or a piece of a pigtail (cork screw looking). I can get a photo of them next time at the hangar (from those I caught in the vacuum canister). I think there are only a very few remaining in the cylinder. I am looking at irrigating the cylinder with solvent as sansoneservices advises as a final attempt to remove the last remaining shavings. Do you anticipate that what ever ones remain will be eviscerated during combustion and will just be blown out the exhaust valve?

The material he was tapping is definately aluminum.The smaller speck/glitter type Al debris is absolutely fine. That type of stuff is always coming off the piston pin caps and does no damage. The pig tail stuff would be good to get out. If lucky, it bounces around, breaks up and goes out the exhaust. However, it could break up into smaller pieces and get stuck between the ring and the ring land, where it restricts movement of the ring; low probability, in my opinion.

No real issues with doing a flush. However, be certain that you re-introduce oil into the cylinder, via the spark plug hole, before running it again.

 

[Mel]

When doing a flush, it might be a good idea to raise the opposite wing so that the cylinder slope is toward the spark plug hole.

May be over kill, but couldn't hurt!

 

[Dandlac58]

Need to consider what type of material the shavings are made of. Brass from the adapters and aluminum from the head are both softer than the steel barrel and rings. Piston is aluminum and could be scratched in theory but my biggest concern would be clogging of the ring lands or ring gaps. That being said, if you have removed most of the material then I wouldn’t worry about it too much. Its fairly common to replace those threads with the procedure your mechanic employed.

Hi Storm_pilot,
I am 99 percent certain they are aluminum shavings, the look "shiney and silver" visually and some are little chips/flecks, others look more like a sliver, and still other resemble parts of a cork screw or pigs tail. I've captured most of them in the vacuum cannister. Im going to check them for magnetic attraction to confirm what they are. I expected that what my A&P did was fairly common, he is quite well experienced, I guess if there is any concern, its that he did not do a thorough attempt to remove the shavings from the cylinder. When I stuck my borescope into the cylinder I was quite surprised at the mound of shavings. I do think I have gotten the vast majority out of the cylinder, hence, my thought to "turn" the engine several times (at idle cut-off on mixture and circuit breakers pulled on the pmags) and with both plug holes open so that the remaining bits can make their way out through the plug holes or the exhaust valve.
Thanks,
Dan

 

[Dandlac58]

The material he was tapping is definately aluminum.The smaller speck/glitter type Al debris is absolutely fine. That type of stuff is always coming off the piston pin caps and does no damage. The pig tail stuff would be good to get out. If lucky, it bounces around, breaks up and goes out the exhaust. However, it could break up into smaller pieces and get stuck between the ring and the ring land, where it restricts movement of the ring; low probability, in my opinion.

No real issues with doing a flush. However, be certain that you re-introduce oil into the cylinder, via the spark plug hole, before running it again.

Excellent! Thank you LR! I've removed all the pig tail type of debris. How much oil should I re-introduce if I should do the flush procedure? A couple of shots from an oil can?

 

[Dandlac58]

When doing a flush, it might be a good idea to raise the opposite wing so that the cylinder slope is toward the spark plug hole.

May be over kill, but couldn't hurt!

Not a bad idea and easy enough to do. Definitely not over kill in my estimate, trying to avoid any engine damage and also save 2-3000 dollars in a cylinder replacement. My other concern is solvent going past the rings into the sump? The compression on the cylinder was excellent when A&P performed the compression test, 78/80.

 

[lr172]

Excellent! Thank you LR! I've removed all the pig tail type of debris. How much oil should I re-introduce if I should do the flush procedure? A couple of shots from an oil can?

Yes and then rotate the prop by hand a couple times to distribute it. If all of the larger stuff is gone, don't think a flush is necessary, but if It gives you peace of mind, no problem doing it.

 

[Dandlac58]

Those shaving are either aluminum or carbon. Both are softer than the steel piston rings or the hardened steel cylinder walls. I would slowly rotate the engine till the piston of the affected cylinder is at top dead center, then try removing them again. Blow gun through the top plug hole should blow them out the bottom hole. Doubtful they would harm anything even if they had to exit via the exhaust system. FYI for next time. Rotate the engine to TDC on that cylinder BEFORE repairs. This can be done via borescope through a spark plug hole [make sure both valves are closed] or remove the valve cover, rotate engine by hand until both valves are closed and the TDC mark on the back of the ring gear lines up with the crankcase parting [seam] line. That will aid in removal of any foreign objects, particularly if you drop something steel in by accident.

Im pretty certain they were aluminum, like 99.9% and will make it 100% when I test with a magnetic those which are in the vauum cannister. I did have that cylinder at TDC when I started working on removing all debris, then I also rotated the prop just a little to move the piston farther down into the cylinder to get a better look with the scope and to make sure there weren't any large pieces of debris still in the cylinder.

 

[Dandlac58]

Yes and then rotate the prop by hand a couple times to distribute it. If all of the larger stuff is gone, don't think a flush is necessary, but if It gives you peace of mind, no problem doing it.

I will go back in with the scope and do one last thorough inspection to make sure everything big is gone, and if necessary apply air pressure and vacuum, to remove. Not particularly wild about doing the flush but will suck it up and get it done if necessary. I really want to minimize any potential damage to the engine - its a really good strong engine with 907 hours on it.

 

[chaskuss]

Next time you need to remove spark plugs, I would suggest using either a 22mm or 7/8" offset box wrench to hold your adapter while you remove your spark plug. I'm assuming here, that these are the correct sizes for your adapters. Correct me if I'm wrong. You can find photos of these wrenches, & where to buy them cheaply at posts 57 & 58 linked below.

Reinstalling ND Alternator Pulley & Retaining Nut thread

 

[Dandlac58]

Next time you need to remove spark plugs, I would suggest using either a 22mm or 7/8" offset box wrench to hold your adapter while you remove your spark plug. I'm assuming here, that these are the correct sizes for your adapters. Correct me if I'm wrong. You can find photos of these wrenches, & where to buy them cheaply at posts 57 & 58 linked below.

Reinstalling ND Alternator Pulley & Retaining Nut thread

That's a really good idea. Thank you.

 

[chaskuss]

That's a really good idea. Thank you.

It's much easier than fabricating a tool as shown in

Starkeys Custom Spark Plug Wrench