So, I had some arcing from the base of my spark plug wires to the block. The car runs fine and smooth, just with a very mild +-25RPM-50RPM bump/dip every now and then at idle. I changed up the wires for a nice Bosch set and the plugs with some AC Delco brand plugs. The arcing still continues, but the car still runs fine. The metal wire shields are still on.
Should I be worried and dig deeper? Or is this "somewhat acceptable" for our cars?
By the way...out of all the things I have done to the car (full suspension replacement, full brake replacement, and a few other odds/ends), the firewall plugs were a walk in the park. I am surprised by all the threads of how difficult they were and the things people have done (removed the decklid, lowered the cradle, come from underneath the car...). I was ready for a nightmare, but all I did was just sat in the trunk, removed the small intake hose and used a ratchet with only a 3" extension attached for all three plugs. To anyone else who gets freaked out from reading other threads...don't. It is easy!
Possible causes. Always use dielectric grease inside the boots. Spark plug gap too large. Cheap spark plugs that do not have the ridges on the insulator ceramic. Fuel mixture that is too lean. (possible egr valve not closing at idle).
[This message has been edited by greaser (edited 02-14-2014).]
Possible causes. Always use dielectric grease inside the boots. Spark plug gap too large. Cheap spark plugs that do not have the ridges on the insulator ceramic. Fuel mixture that is too lean. (possible egr valve not closing at idle).
I used a generous amount of dielectric grease in each boot, the plug gaps are all at 0.45 and the plugs have the OEM ridges. Not sure if a lean mixture exists, however.
Yeah, it's not that bad... unless a plug breaks off in the head.
Ha! Helps to be 6'2" and be able to lean on the intake plenum. I was lucky that the plugs were low on rust and it wasn't a fuss. It began as one of those, "I know these plugs are good...I don't really need to change them" moments. And you know how those "I don't really need to fiddle with that" moments can historically turn into the worst moments, which ends up in you cursing yourself for not listening to yourself in the first place. Thankfully not on this instance.
Ive seen plugwires and Vac lines (Rubber) Glow like neon tubes with each pulse. Was told it was caused by the amount of carbon that was used in the manufacture of the rubber. Changed everything to 8mm silicone jacketed wires and silicone Vac lines and it was gone. Looked cool as hell with the shop lights out.
Originally posted by Patrick: I've heard that arcing from the metal boot shields to the heads is normal. I believe it's due to electromagnetic induction.
For this reason, I nixed the metal heat shields, and only use high-quality spark plug wires with silicone insulation.
I doubt the arcing between the metal shields and the head is going to hurt anything. But I'm kinda paranoid about stray electricity and engine fires.
For this reason, I nixed the metal heat shields, and only use high-quality spark plug wires with silicone insulation.
I doubt the arcing between the metal shields and the head is going to hurt anything. But I'm kinda paranoid about stray electricity and engine fires.
I would have guessed that the metal shields were for heat prevention, to protect the boots....but what do I know.
I am also doubting the arcing is doing any harm, but some people outside of our car community seem to think it is not good, so I figured I would pick all of your brains, just to make sure
Originally posted by MacGyversMullet: I would have guessed that the metal shields were for heat prevention, to protect the boots....but what do I know.
I believe they were. The big question is whether or not that was really needed. I have my own opinion regarding that. But I'm sure others will differ.
Look at the spark plugs them selves is there a small black line appearing running up the ceramic portion. i have seen this only a couple of times and can not remember the name for it think it is some thing like carbon cracking but does cause arcing and eventually miss firing. Dan
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DARN Cars now open with Over 30 years wiring experience between cars and trade as an avionics technician in both Canadian Air Force and civilian aviation. Over 25 years experience building and modifying cars. Over 10 years of full Fiero engine swaps and harnesses building and still going.
Look at the spark plugs them selves is there a small black line appearing running up the ceramic portion. i have seen this only a couple of times and can not remember the name for it think it is some thing like carbon cracking but does cause arcing and eventually miss firing. Dan
Carbon tracking is the term I've always heard. The metal shields are suppose to be for heat issues, I removed mine with zero problems. Also, here's something that made my spark plug changes even easier, get a stubby 3/8 drive ratchet. Trust me on that one!
Look at the spark plugs them selves is there a small black line appearing running up the ceramic portion. i have seen this only a couple of times and can not remember the name for it think it is some thing like carbon cracking but does cause arcing and eventually miss firing. Dan
Dan, good point, but neither the old plugs nor the new plugs show any sign of this. No other funny signs from the old/new wires/plugs either. Everything is as it should be, minus the arcing. If it isn't something I should worry about, then I am fine with it.
Just a few points. Dielectric grease/compound is used to conduct heat away from a component to a heat sink. I.E ignition module to distributor housing. The grease that comes with spark plug wires is just silicone grease. Mainly used to keep the boots from adhering to parts. Helps keep you from tearing off the boots when you take them off the next time. Also helps keep moisture out. With the newer better materials used on spark plug wires, the metal tubes are not needed unless the wires could come in contact with the heated metal parts. Have had the tubes cause more problems then help. I have seen carbon tracking on the center electrode cause the plug to arc up the insulator and then to the side of the plug. This normally happen after crap has been burned off (overly rich conditions, or run continuously cold) and the carbon sticks to the side. The tracking seen outside off the plug is not carbon, but some kind of metal track from something metal rubbed against the insulator. Take a piece of steel and wipe it across a piece of ceramic and it will leave a fine metal line on the ceramic/glass. Sometimes removing a socket on enough angle can cause this. Use anti seize compound sparingly. Only use enough to just lightly coat the threads. Too much can cause the compound to move up the threads and onto the seal surface when installed. The tapered seal surface of the plug and head needs to be clean. If you have to, take a small round wire brush to the head taper. Especially on old heads. Any rust or dirt can keep the plug from sealing right. This will cause small compression release and contaminate the threads with heated exhaust gases. This can cause seizing. Especially on aluminum heads. This also causes higher resistance. Causing more likely hood of arcing. This and loose plugs causes them to vibrate, which leads to insulator breakage.
[This message has been edited by cmechmann (edited 02-15-2014).]
Way back when better thermal compounds came out we used dielectric grease. Before the white grease. Before the metal powdered stuff. Before dielectric grease, Mica pads were used. But back then it was used because it did have some thermal conductivity. And we used it until newer, cheaper compounds came out. After the other compounds came out, we used it on wires until it was just sold as silicone grease. I used some on some of my first 80386s. Had some left over in my drawer. They didn't require heat sinks, but I did notice less temps when using it. While working for Chrysler in the late-late 70s/early 80s when they were using Lean Burn systems we also used it under and over the tips of the distributor rotor and on either side of the contacts on the side of the distributor cap. This was before they were using higher energy coils and helped keep the spark flow more direct. Helped keep the spark from expelling off or to the side of the contacts. It did make a small difference and the system could be leaned out a little more. That practice has also went away.
