Who can read spark plugs?

[KaGee]

I've got a 3.8L V-6 Chevy. Pertronix ignition. Developed a little bog while trolling Monday and the engine died. I thought she was just loaded up a little (we been trolling a while). Restarted and gunned the engine depositing black carbon in the water. We trolled a little more but something was not quite right. Pulled the remaining lines and went in. It felt like I was down a cylinder. RPM and speed was down. The boat has sat until I could look at it today.

I think I found the fouled plug (#2) as it was slightly wet. We had a long ride in the channel at no wake after the run in, so I expected to see them a little black. But look at these and tell me what you think.

Especially this is interesting:

I've installed new plugs, but due to a weather front that blew up that's all I've done for now.

 

[b0mbtrack]

Re: Who can read spark plugs?

i've never seen a plug that color

 

[KaGee]

Re: Who can read spark plugs?

i've never seen a plug that color

Me either... I put $50 of SUNOCO Premium in it to offset some older fuel... could there be something in that fuel leaving the red residue?

 

[b0mbtrack]

Re: Who can read spark plugs?

but why just one plug?

 

[sabastianunf]

Re: Who can read spark plugs?

lt looks like rust. if it is then you have a bad exhaust manifold. Symtoms sound about right as well. at lower rpm's water can pass back into the combustion chamber and cause that cylinder to not fire and the motor to stall. At higher rpm's the water is kept out by the exhaust pressure.

 

[KaGee]

Re: Who can read spark plugs?

No, it's not rust. It's on all the plugs, just more intense on that one.

 

[Gary H NC]

Re: Who can read spark plugs?

That is strange Kagee,I have never seen one that color either. Was Stabil in the fuel or any other additive? Still wonder why so much more on that one plug.
Maybe the premium at the pump was old due to the high prices and nobody is buying much of it?

 

[WAVENBYE2]

Re: Who can read spark plugs?

I'm sorry, but I can't wait to see the answer for this one either, I hope it's not serious ....PAT

 

[Reel Poor]

Re: Who can read spark plugs?

The plugs don't look that bad. They all look like they're quite fat at idle (notice the black soot all the way around the flat edge of the threaded part of the plug). The rust color is most likely residue from a manganese fuel additive.

You've got e-mail.

 

[Boatist]

Re: Who can read spark plugs?

The plugs all look very bad to me. The center parts whould be white or light gray not dark gray to black. Look a lot like the plug in my out board when I was haveing a lot of fouling problems. When the new outboard TCW 3 oil came out I had a real problem with plugs fouling. Would have to change every other day. Today I belive the problem was just lots of carbon in the engine and the new TCW 3 oil was cutting in out but fouling the plugs. After I used OMC Engine Tuner the plug looked worse than yours. Then after that nice and white with no black on them at all and the fouling problem was gone.

I had a friend back in the 70's that used shell gas and his plug were always pink/red. He changed brands and look normal from then on.

I would do a compression check first to make sure your miss is not a bad valve. Then I would run OMC engine turner thru you motor or Seafoam and run it out good. After that change the plugs and see what happends.

 

[whywhyzed]

Re: Who can read spark plugs?

Did you put a LOT of Stabil in the tank for the winter?

Seems to be a lot coming up on google about fuel additives turning things red, o2 sensors, spark plugs etc....

At idle, #3 and #4 are a lot closer to the carburetor I suppose..... would maybe get more of what precipitates out or more fuel in general.

The plugs look OK aside from the rich look and red....

I'd probably run through the idle mixture setting, and see if the screw is on the rich side.

 

[whywhyzed]

Re: Who can read spark plugs?

Just went and pulled my #3 plug.... I haven't idled much... a few minutes before shutting down.
I'm still on the carry-over fuel with Stabil in it.

 

[KaGee]

Re: Who can read spark plugs?

I used Pri-G for stabilizer in the fall.

I talked with a mechanic friend this morning... Reel Poor hit on the same subject that my friend mentioned... fuel additives... not by me, by the refiners. Says he pulls a lot of plugs with red residue. Said nothing to worry about as far as the residue is concerned.

Have to re-check my air mixture adjustments.

 

[Coors]

Re: Who can read spark plugs?

I don't know if it still does, but in the late '60s, Hess would color the plugs pink..