Topic: What to use to clean cabon fouled plugs?

[Steve F]

I tend to disagree with folks with an aversion to bead blasting plugs.

Its the routine way to clean aircraft spark plugs....

After about 20 years of cleaning plugs this way I've yet to see "glassing" or "glazing" or anything of the sort.

Now when I say this keep in mind I've dealt with alot of spark plugs....we're talking 14 and 18 cylinder air cooled radial engines.

Two Plugs per cylinder

A LOT of spark plugs.

We're talking inspecting plugs with a magnifying glass.

We're talking about spark testing before and after cleaning. Spark testing under pressure (yeah I have the machine, 100+ psi).

Glass bead hasn't done a bit of damage that I have EVER seen.

Most plugs I've seen have been killed by dropping or otherwise subjecting them to impact.

Cracks the insulator.

I agree that bead blasting has and still does a superior job of cleaning the plugs, but I have seen where the grit gets trapped in the plug, way up where it's hard to see, between the insulator and the body of the plug, and has later fallen out of the plug and ended up in the combustion chamber.  If you use the bead blasting cleaner, you just have to be really careful and remove all of the grit before you install them.  I had a plug that looked really good after I bead blasted it, and when I went to install it, the grit contaminated the plug threads, and galled.  Luckily, it was on a cast iron head, and didn't do too much damage...had it been an aluminum head, it would have been "heli-coil" time.

[kghost]

Well if you don't clean grit out of the plug...I guess that could happen...

I believe that bead blasting has added benefits.

Really gets the internal cavity and walls clean.

After all thats what wicks the heat away from the plug tip.

Contamination inhibits the heat transfer.

Additionally you can see defects better when they are clean.

[goon 1492]

I've gotta say I have always reused some of my plugs, espically if they are still new. There is simply nothing wrong with them, and like King and many other stated I use carb cleaner a brass brush and some compressed air. This trick started out for me with my old 250 elsinore, you wouldn't believe how many times I buried that beast and fouled a plug only to grab an old one out of my goodies in the middle of nowhere and that old plug got me back home having fun all the way.
we also had a fancy blaster in automotive school that would blast the plugs and test them, our teacher said that this doesn't always work for the plugs as they get older and just to get new ones.