Has anyone seen this happen to a spark plug wire? Car is 84 T/A, carbed. Ran it all summer and never had a problem. The only thing I can think of is that is started when it got cold and I let the car run on high idle for 5-10 min to warm up and it gets to hot. Only that one plug is doing this. I'm ordering anew set of MSD plugs now. Does anyone have an idea of what could cause this? Running hot obviously...but just hot or could I be having something else going on?

 

Retarded timing or lean mixture will make your exhaust run hot. Especially during your warmup high idle. Can you see the headers glow if you run it at night? Mine were red hot and cooked my wires right after my engine swap before i got everything adjusted.

And is that your number 5? I think that was the first one to start glowing on my own.

 

Possibly the terminal inside the boot wasn't making good contact causing internal arcing and going through the insulation to the outside. Question, in your pictures what is below the wire that is also cracking?

Because there's not much room to route wires away from my SLP headers I use boot insulators like these. http://lh5.googleusercontent.com/pub...yy61vfPZsx=s90 The next time I change wires I'm replacing these with 12" insulators.

 

That's the rest of the wire/boot. It's completely blown up like that. Bubbled up all white and crusty and rotted away from the inner wire. The car still runs fine..for now. I'm sure it'll start arcing soon enough.

I have a set of those wire protectors but I cannot get them to fit over the boot ends of my MSD wires...so I wasn't able to put them on. if I could figure out how to take the boot ends off I could get them on but I haven't been able to figure it out.

 

Is it that the boot is too bulky?
The end of the insulator with the ring goes goes on the plug side of the boot.

 

I know "where" they go, but the ring itself doesn't fit over the boot. I tried fishing it in thinking the ring went aorund the plug itself and the shielding covered the whole boot but that didn't work. I always buy the assembled spark plug wires...do the boots themselves come off or are they permanently attached? If the boot can come off, then I maybe I could put it over the wire..put the boot back on, and cover it that way. Hmm...

 

I think your melting the **** out of those wires with the headers !!!!

same thing happend to me on my suburban !! Now i got custom wires made ..160 bucks and they are awsome !!!!!

 

What plug wires are you running?

 

they are 9 mm or so with a special wrap around them..a guy here local makes them...don't know what brand..lol
But my 600 CI race engine in the boat likes them too and the exhaust temp on that one is 1400 degree.

he can make blue,red and black...maybe other colors ??!!!

 

if you cant get the wire protectors on can you wrap the header with heat wrap?

 

I'd swap that one wire out with another, see if it happens again. Looks like it cooked itself from the inside out.

 

Just a thought, but I had a similar problem with my '89 Firebird (2.8 V6). Turned out to be a leaking exhaust gasket.

 

Here's some pictures of mine.
Insulator without the wire in it, the ring is on the left.

Wire shown on the outside.

Wire and insulator installed.

 

Wrapping headers is not for street cars. The wrap traps moisture and cause rust that will eat right through the headers.

 

I find that hard to believe...

Water evaporates at a far lower temperature than the headers will reach, even lower temps at higher elevation like where I live

 

Here's a forum where the subject is discussed.

http://www.thumpertalk.com/forum/arc.../t-535952.html

High grade stainless steel tubing takes longer to rust, using a high temperature sealant on the tape is a must. Ceramic coating would be a better choice plus it looks good.

 

Ive been using exhaust wrap on my headers for years now. As long as you keep the engine compartment dry, the headers will do OK. Its true that you do get a bit of rust after a while. I re-wrapped my hookers, and they had some surface rust. Nothing major, though. Much better having a small ammount of rust than nuking several thousand dollars worth of electronics and wiring from all the heat. I will say that if the car is kept out in humid conditions and not driven, it can be an issue. The condensation soaks in and can cause quick rusting if its allowed to sit for extended periods of time. I left a set of wrapped headers out of the car and they definitely had a decent ammount of rust from sitting.

Since your carbed and the wires are the only thing thats being damaged, then the insulating boots are a good solution. I also used aluminum heat shields at one point as well when I still had straight plug heads, and that works well also. The thing that causes all the problems is that some of the pigments used to color the silicone absorb infrared, leading to the wires getting too hot. Deflecting the radiation goes a long way to keeping them cool.

 

The new wire set should be here today or tomorrow. I"m going to swap out that wire and put the heat protectors on them to see how that helps. I wonder why it waited until now to do this. I've been running the car since July with these plug wires and nary had a problem till I saw this last week and I am under the hood at least once a week.