Plug Assessment

[Bingster]

This is a plug out of one of the cylinders of my flat head six.  I thought it was a little suspicious and thought I'd put it on here for evaluation.  It looks like there is a type of fuzz on it like we have on our apple trees. But there are no apple tree in cylinder one that I know of. It came out of the head harder than the others and with a light squeek, undoubtedly from the rust on the threads. Wait. Don't tell me. I don't wanna know!

Edited September 15, 2017 by Bingster

[Dodgeb4ya]

When is the last time it ran?

[Bingster]

Seven years ago.  Been sitting under cover since.

[Los_Control]

For what it is worth, if there was water getting into the cylinder while running, the plug would be a real clean light colored from the water.

Also the plug would be harder to remove.

I broke a plug on a 80's toyota 4 cylinder with a leaking head gasket. Which is where I read up and learned about the issue. The car ran great, I did not think it had a blown head gasket.

 

I do not know anything about the fuzz, but it appears to be burning cleaner then the others and makes me wonder.

[Bingster]

All of the plugs have the electrodes even with the bottom of the threads, which is quite a bit lower than the new R45's I have. Are these old ones that worn?

[Reg Evans]

That looks like a similar growth you will find on the contact points after a long rest.

[Los_Control]

When looking at the plugs, is the edge of the electrode that shows the wear.

Worn the edge will be rounded, sometimes they are no longer flat and slope to one side with part of the electrode burnt away.

Also the gap is a clue, if they were gapped properly in the first place.

From what I see, looks like you could clean those up and reuse them. Worn edges and mushroom shaped electrodes will spark off of the sides in a larger pattern and basically weaker then a plug in good shape.

A good plug with sharp edges will fire straight up.

[Bingster]

The electrodes are still square.  My service manual says .025 but seems like a lot of you guys like .030.

[Dodgeb4ya]

Looks like the engine ran a little rich and burned some oil.

Plugs don't look eroded excessively. They are no good as is IMO.

[Bingster]

Yeah, buying new ones seems like a good investment.

[greg g]

Spiders????

[Bingster]

Well you know, the first thing I thought was that it looked like seat stuffing and I thought, "Oh no, a mouse got into the engine." But that's silly, so I thought water in the cylinder. But I like the spider idea much better.

[Silverdome]

Looks like cotton candy. Hopefully nobody sugared the tank and that's why the engine was pulled but I would bet on spiders first since it is only one plug. The .025 gap would be correct for non resistor plugs I believe.

[JOHN EDGE]

Don't think you gain much info from those plug. Get it running if you can. Do a compression and leak down test. Go from there

[keithb7]

I wonder if that cylinder with the cooties on the sparkplug has been dead for some time?  Maybe no compression for some time when the engine was at least last running?

The reason I say this is, I found similar spider web type stuff in a dead cylinder of my running 1953 L265. I had done a compression test and found #6 was dead. See pic below. See the white spider web-ish stuff on intake valve #6. This engine was running but #6 intake was stuck open. So no compression. No explosion. Cylinder was dead. Ignore #5 intake valve here. It was bent. But that happened just before I pulled the head, and snapped this pic.

[Bingster]

That's a possibility.  My my mechanic and I fire it up he's gonna check compression, etc.  We'll see what kind of engine I have.