Spark Plugs To Blast or Not to Blast

Huckster79

Huckster79

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Huckster79
Just got all the supplies for doing my own spark plug rotation and cleanings. Being I fly about 150 hours a year, just makes sense to do myself. Bought all the goodies that I didn't already have, the right socket, gaskets, rack, Anti-sieze, gapper guage and tool, etc and the $39.99 vibrating or ultrasonic cleaner from Spruce, but also noticed they sold a blaster unit for cleaning, some of the comments was it was really just a HF one. So I stopped by and grabbed one at HF today and then got reading up on the cleaning process....

Looks like blasting them is not a unversally accepted thing to do...

What do you guys n gals do with cleaning them and why? I see the disadvantage of blasting is wear, whats the upside of blasting it instead of just the vibrating cleaner?
 
The problem with those little bean bag blasters is that you can't see what your doing. So you have to keep pulling it out and turning it around in a blind attempt to blast the area that's been missed. If you put a plug in a regular media blast cabinet where you can see it only takes a couple of short shots and you're done. Does it abrade? Well sure but you only do it once a year so nothing like the 20-30 arcs per second it's getting while you're cruising along. The question above of fine-wire is because like platinum plugs in a car, they are self cleaning and don't require blasting though they will still accumulate lead deposits in the well.
 
I prefer glass bead blasting for plugs, in a cabinet, but because the bead is nearly invisible you have to be really diligent and use a light and some strong reading glasses and have a good look in that well to see that you don't have any bead stuck in the crevice between the steel and ceramic. Bead there will fall out into the cylinder and cause serious scoring.

The sparkplug cleaners use silicon carbide grit. It's really hard and really sharp. That stuff for sure you want to make certain isn't stuck in the well, and it's also much harder on the plugs. Both bead and silicon carbide will peen the ends of the electrodes if you blast too long, mushrooming the metal over a bit and closing the gap, making accurate gapping more difficult.
 
I have a Champion spark plug cleaner/tester. After using a dental pic to carefully (carefully!) remove the lead deposits I blast, but not for more than 1 to 2 seconds. That's all that I've ever needed, then regap, test and put 'em back in. If you are running a Lycoming note the most recent service bulletin on the topic states copper based anti-seize now. I'm using Loctite C5-A.

https://www.lycoming.com/sites/default/files/SI1042AH Approved Spark Plugs.pdf
 
I don't blast spark plugs, I've never found a need to. I just pick the large lead deposits out, check/set the gap, and rotate the plugs.
 
mondtster said:
I don't blast spark plugs, I've never found a need to. I just pick the large lead deposits out, check/set the gap, and rotate the plugs.
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+1. If any doubts a pressure check and/or resistance check may be in order. Regardless, always recommend someone who is performing this for the first time to follow the OEM procedures until they get a handle on the process. Gives a good foundation and a convenient reference for the log entry.
 
mondtster said:
I don't blast spark plugs, I've never found a need to. I just pick the large lead deposits out, check/set the gap, and rotate the plugs.
Click to expand...

I used to, but with aggressive leaning during taxi (and LOP running at cruise), they stay quite clean. If they looked to be fouled with oil I'd probably blast, but deposits are minimal and healthy in color.
 
SoCal RV Flyer said:
I used to, but with aggressive leaning during taxi (and LOP running at cruise), they stay quite clean. If they looked to be fouled with oil I'd probably blast, but deposits are minimal and healthy in color.
Click to expand...
If I found oily plugs I cleaned them with non-chlorinated brake cleaner first, blowing them dry, sometime several times to get them oil-free. Any oil in there will trap the grit. And oil getting into the blaster lumps up the grit.
 
Another example of the crazy aviation prices. With my car, I don't bother to clean the spark plugs, at $3 each I'll just spring for $20 in new plugs, especially since after I have removed them, I might as well put in new ones. But at aviation spark plug prices, I'd be cleaning them haha.
 
Regardless of what kind of bead blaster you use, keep in mind that those beads can not be trapped by an oil filter. If any of them make it into a cylinder they can never be trapped by the oil filter and can make it past the rings into the crankcase. Take all measures to see that no glass beads are left on the plug.
 
MBDiagMan said:
Regardless of what kind of bead blaster you use, keep in mind that those beads can not be trapped by an oil filter. If any of them make it into a cylinder they can never be trapped by the oil filter and can make it past the rings into the crankcase. Take all measures to see that no glass beads are left on the plug.
Click to expand...
Wut?
 
Repeat: The glass beads used in a bead blast process are too small to be trapped by an oil filter. Even though they would be introduced into the combustion chamber, they can make their way to crankcase and be circulated in the oil doing microscopic engine damage.

The point is to blow off the plug thoroughly after cleaning in an effort to remove all beads to prevent unnecessary engine wear.
 
I think a resistance check and a check of spark plug operation under pressure is important.
 
MBDiagMan said:
Repeat: The glass beads used in a bead blast process are too small to be trapped by an oil filter. Even though they would be introduced into the combustion chamber, they can make their way to crankcase and be circulated in the oil doing microscopic engine damage.

The point is to blow off the plug thoroughly after cleaning in an effort to remove all beads to prevent unnecessary engine wear.
Click to expand...
Those glass beads are huge compared to the other stuff a filter catches. The smallest beads are around .002" and the typical #10 is around .005". A 10-micron oil filter will catch stuff above 10 microns, which is .00039".

Bead shatters into smaller stuff, and the dust might get past filters, but the dust is far easier to blow out of a plug than a bead wedged in the crevice between the metal and ceramic. That's the critical stuff.

Hard carbon breaks off the piston and cylinder head and gets everywhere and tears stuff up, too. It's the nature of these engines. Proper leaning can minimize that buildup.
 
I can’t lean for taxi- the Stromberg carb doesn’t work that way... though I do run Mogadishu when I can to help....
 
Dan Thomas said:
Those glass beads are huge compared to the other stuff a filter catches. The smallest beads are around .002" and the typical #10 is around .005". A 10-micron oil filter will catch stuff above 10 microns, which is .00039".

Bead shatters into smaller stuff, and the dust might get past filters, but the dust is far easier to blow out of a plug than a bead wedged in the crevice between the metal and ceramic. That's the critical stuff.

Hard carbon breaks off the piston and cylinder head and gets everywhere and tears stuff up, too. It's the nature of these engines. Proper leaning can minimize that buildup.
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Don't try and correct him, he "Repeated" himself. We all know the schoolyard rules - if you say Repeat: there are no corrections allowed. Those beads don't have to follow the normal rules of physics. Repeat: those beads don't have to follow the normal rules of physics.
 
I’m only going by a TSB I read decades ago. Took it for the truth and have been careful with those beads ever since.
 
I have not had fouling with massives but I am sold on fines. They cost less per hour, never need gapping since the erode so little, you would never blast them. Just use pick to get out the lead balls. There is dyno report that fines give couple a percent more BHP which should mean less fuel/BHP which would mean free plugs with the fuel savings compared to massives..
 
Personally I never use a pick to get lead deposits out. wedging and prying with a pick is a good way to crack the ceramic. Use the vibrator, that's what it's for. Very gentle intrusion and no need to force anything.
 
Appreciate the insights in this thread. I think I’ll pick up one of the vibrator-type cleaners.

I do have the blast type and have been picking out the lead carefully then blasting just for a few seconds then blowing out. Good point about the abrasive, though.

Which leads me to a question: looks like ATS sells a walnut shell-based medium for this. Any thoughts/experience with that stuff? $2.50/bag seems reasonable!


https://aircraft-tool.com/shop/detail.aspx?id=78W
 
Huckster79 said:
What do you guys n gals do with cleaning them and why?
Click to expand...
Installed a G3I harness:
https://www.g3ignition.com/
Slick harness_320x240.jpg
Slick and Bendix magneto harness lead replacement allowing the use of automotive style spark plugs with

stock magnetos. Complete harness conversion kits, with instructions to convert one or both magneto harnesses.



I run
NGK (3961) BR8ES-S
just change them at annual. They are cheap enough to not bother with cleaning or testing. Of course I'm in an experimental...
 
FORANE said:
I run
NGK (3961) BR8ES-S
just change them at annual. They are cheap enough to not bother with cleaning or testing. Of course I'm in an experimental...
Click to expand...

Back in the 90s I had a couple of Kawasaki jet skis that used BR8ES plugs. I think I still have a couple in a drawer somewhere.

:D
 
3393RP said:
Back in the 90s I had a couple of Kawasaki jet skis that used BR8ES plugs. I think I still have a couple in a drawer somewhere.

:D
Click to expand...
Yes, though there are a couple of different variants of the BR8ES (5422 and 3961). It's nice buying plugs at $1.99 each.
 
Huckster79 said:
Just got all the supplies for doing my own spark plug rotation and cleanings. Being I fly about 150 hours a year, just makes sense to do myself. Bought all the goodies that I didn't already have, the right socket, gaskets, rack, Anti-sieze, gapper guage and tool, etc and the $39.99 vibrating or ultrasonic cleaner from Spruce, but also noticed they sold a blaster unit for cleaning, some of the comments was it was really just a HF one. So I stopped by and grabbed one at HF today and then got reading up on the cleaning process....

Looks like blasting them is not a unversally accepted thing to do...

What do you guys n gals do with cleaning them and why? I see the disadvantage of blasting is wear, whats the upside of blasting it instead of just the vibrating cleaner?
Click to expand...
The vibrating cleaner works really well
 
Silvaire said:
Personally I never use a pick to get lead deposits out. wedging and prying with a pick is a good way to crack the ceramic. Use the vibrator, that's what it's for. Very gentle intrusion and no need to force anything.
Click to expand...
Would you use a vibrator on fines? I have never cracked the ceramic in 8000 hours. Am I that good? Probably.
 
Standby for thread drift.....
All this talk of abrasive blasting (or not blasting) spark plugs reminded me of my first job as an auto mechanic (too many years ago). Just out of high school, I had no real experience other than working on my own car and some friends cars. After quite a few rejections, the owner of a small foreign car shop not too far away said he would give me try. My first task is a tuneup on a VW Bug. As I drive the car in I’m thinking this is good I’ve worked on VW’s before I’ll knock this right out. The boss says the book is over there for the specs and the plug cleaner is on the bench. The plug cleaner is one of those small sand blasters with an attached cloth bag of abrasive like the ones discussed in this thread. I hadn’t used one before but hooked it up to shop air, a couple of quick blasts for cleaning, blew them out with shop air to get out the sand and the plugs looked like new - cool. Plugs back in, set the points and I go to start the engine to set the timing- it cranks but no trace of attempting to start???? This is my first task, I can’t ask for help. Got to figure this out, what did I screw up! Seems like it must be ignition, but there is spark at the coil and plug wires, timing has to be close, I drove it in. By now the owner (and other mechanics) are checking on my progress. I sheepishly describe what happened and the troubleshooting I’m doing try and resolve the problem, without success and thinking I’m done on the first day. The boss thinks about it, asks a dew more questions and finally says “that’s weird - throw in a new set of plug”. I do and the car starts instantly.
Sometime later I learn that the shop owner adds a bit of graphite powder to the plug cleaner abrasive as a “stress test” for a new mechanic. The trace of conductive graphite left on the plug is nearly invisible but insures the plug won’t fire even though it looks perfect.
So, in conclusion, if you do decide to blast, with an abrasive medium of your choice - don’t choose or add graphite.
 
Last edited:
Hank195 said:
Standby for thread drift.....
All this talk of abrasive blasting (or not blasting) spark plugs reminded me of my first job as an auto mechanic (too many years ago). Just out of high school, I had no real experience other than working on my own car and some friends cars. After quite a few rejections, the owner of a small foreign car shop not too far away said he would give me try. My first task is a tuneup on a VW Bug. As I drive the car in I’m thinking this is good I’ve worked on VW’s before I’ll knock this right out. The boss says the book is over there for the specs and the plug cleaner is on the bench. The plug cleaner is one of those small sand blasters with an attached cloth bag of abrasive like the ones discussed in this thread. I hadn’t used one before but hooked it up to shop air, a couple of quick blasts for cleaning, blew them out with shop air to get out the sand and the plugs looked like new - cool. Plugs back in, set the points and I go to start the engine to set the timing- it cranks but no trace of attempting to start???? This is my first task, I can’t ask for help. Got to figure this out, what did I screw up! Seems like it must be ignition, but there is spark at the coil and plug wires, timing has to be close, I drove it in. By now the owner (and other mechanics) are checking on my progress. I sheepishly describe what happened and the troubleshooting I’m doing try and resolve the problem, without success and thinking I’m done on the first day. The boss thinks about it, asks a dew more questions and finally says “that’s weird - throw in a new set of plug”. I do and the car starts instantly.
Sometime later I learn that the shop owner adds a bit of graphite powder to the plug cleaner abrasive as a “stress test” for a new mechanic. The trace of conductive graphite left on the plug is nearly invisible but insures the plug won’t fire even though it looks perfect.
So, in conclusion, if you do decide to blast, with an abrasive medium of your choice - don’t choose or add graphite.
Click to expand...
That’s an awesome story
 
I often just spray BrakeKleen on plugs and blow them dry with shop air. If they look clean inside with no lead deposits, I check gap, brush old antiseize from threads, rinse and repeat with shop air. I do sometimes use my bead blaster set to very low pressure just long enough to accomplish the job..I do not attempt to make the plug shiny like new. I test internal resistance if the plugs are old Champion types.
 
Dana said:
What's involved in doing the conversion? The website is a bit vague, they want you to pay $30 to download the instructions.
Click to expand...

You can buy the instructions or do as I did and buy a completed wire harness set that includes the cap that screws onto a slick mag. It's plug and play but you will need to provide exact lengths of wire for each plug. I am very happy with it. The motor runs very smooth. Research the difference between the 2 ngk plugs I mentioned earlier. One is preferred.
 
Dana said:
One solid, and one the screw on cap?
Click to expand...
Yes, I use the solid.
My titan doesn't need spark plug adapters because it's tapped for 14mm plugs. You might research plug adapters also.
 
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