something came out with spark plug when removed

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Nov 29, 2009
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I changed the spark plugs on my boat and this boat has had a bit of a misfire since day one honestly. Anyways, lately it's been getting worse. So yesterday when I was changing the spark pugs I could have sworn some metal shavings or something came out with the spark plug when I removed it. Whatever it was dropped into the bilge to never be found again. It's possible it was some paint that flaked off. idk. I didn't get a chance to check for spark, but I did go and get a borescope from advanced auto and didn't see anything unusual. Lots of carbon on the piston, but all the cross hatching is still on the cylinders. What are the chances of their being some debris leftover from when they machined the heads? the engine only has 150hrs
 
If they were original plugs, they may have had paint on them. If the scope didn't show debris, probably isn't any. You could always flush the cylinder with brake cleaner, and then make SURE to put some oil down the plug hole, to lube the rings before running.
 
If they were original plugs, they may have had paint on them. If the scope didn't show debris, probably isn't any. You could always flush the cylinder with brake cleaner, and then make SURE to put some oil down the plug hole, to lube the rings before running.
On a couple of the holes, the paint did come off when I pulled the plugs off. I did see a paint flake sitting on the engine mount just below the plug i pulled out and the backside that wasn't painted, did have a chrome reflective look to it in the light. They were original plugs
 
I had the threads come out with the plugs on a 1975 Johnson once.. Had to put in a heli-coil inserts with the new plugs and cringed every plug change after that.. They were still in there when I sold it though.. Have you done a compression check?
 
I had the threads come out with the plugs on a 1975 Johnson once.. Had to put in a heli-coil inserts with the new plugs and cringed every plug change after that.. They were still in there when I sold it though.. Have you done a compression check?
I didn't see anything wrong with the threads
 
I didn't see anything wrong with the plug
Idk maybe it was my imagination, but I could have sworn I saw stuff come out. Maybe the threads weren't chased properly and it was metal in between the threads.. what are the chances of metal hanging around the spark plug threads from the machining process? Maybe this is what was causing my misfire problem.
 
Idk maybe it was my imagination, but I could have sworn I saw stuff come out. Maybe the threads weren't chased properly and it was metal in between the threads.. what are the chances of metal hanging around the spark plug threads from the machining process? Maybe this is what was causing my misfire problem.
So you're asking people to identify and characterize stuff you could have sworn you saw but might be your imagination?

And then diagnose your misfire problem using the speculation about what the stuff was you might have imagined?
 
So you're asking people to identify and characterize stuff you could have sworn you saw but might be your imagination?

And then diagnose your misfire problem using the speculation about what the stuff was you might have imagined?
I checked all the things they said to check except a compression test. Even bought a borescope and looked at the cylinder walls and you could still see the cross hatching. Relax man.
 
I'm completely relaxed. I just repeated back what you said.
Well, what I was getting at.is maybe there has been a chunk of metal or something stuck on the spark plug grounding out the spark. I've only had a chunk of carbon come off and ground a spark plug out once in about 25 years, so it's not likely. I would think you would see metal all over that cylinder if there was a problem. Agree?
 
Well, what I was getting at.is maybe there has been a chunk of metal or something stuck on the spark plug grounding out the spark. I've only had a chunk of carbon come off and ground a spark plug out once in about 25 years, so it's not likely. I would think you would see metal all over that cylinder if there was a problem. Agree?
Sure, maybe there was. Or maybe not. Even you say it isn't likely, nor do you know either way. Awfully hard for the board to draw conclusions.

Agree?
 
Sure, maybe there was. Or maybe not. Even you say it isn't likely, nor do you know either way. Awfully hard for the board to draw conclusions.

Agree?
I was just asking for ideas of what it could be, other than busted piston rings and a melted down piston. You guys gave me ideas, thank you. That's all I asked.
 
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