Holy crap I'm seeing combustion... 00XLT V8

[dreddog47]

Alright, so my friend has a 2000 XLT V8 with 164k miles on it... Since he got the truck, it has been making a "tick tick tick" noise which I thought was an exhaust leak coming from the pass side. (Before any of you say it, this is NOT lifter tick)I took the pass side splash guard off from the wheel well and didn't see any cracks on the manifold, and the connection to the Y pipe sounded fine... He started the truck and I couldn't feel any air coming out of it either. However, I looked at plug number 3 and I could actually see the spark inside the engine glowing around the edge of the plug. (where the threads are)

What would cause this, and what can I do to fix it?

Loose plug? Wrong size plug? is the head trashed?

 

[Brandon96]

If I'm understanding you right... I'd pull the plug out and investigate the threads first. See if there's any abnormalities like missing threads or traces of the hole being rethreaded.

 

[Joe Dirt]

Agreed- no way of knowing what's wrong until you pull them out.

Does the tick get quieter after the truck warms up?

 

[corkey]

i actually saw this today on a snomobile,, usually what causes it is a crack in the insulator of the plug,, replace it and it should go away,,
what causes it is the resistance of the plug is too much and the spark jumps from the wire connector to the threaded part that goes in the head,,

 

[Brandon96]

Ohhhh, that makes a lot of sense..

I thought he was actually seeing the combustion process through the threads. Misread that. listen to corkey!

 

[dreddog47]

i actually saw this today on a snomobile,, usually what causes it is a crack in the insulator of the plug,, replace it and it should go away,,
what causes it is the resistance of the plug is too much and the spark jumps from the wire connector to the threaded part that goes in the head,,

yep this sounds about right, I'll replace the plug and see if the noise goes away


thanks

 

[Joe Dirt]

What about the tick? That's indication of an air gap, no?

 

[Dan Whitaker]

What about the tick? That's indication of an air gap, no?

Not if the arc is jumping. It wolud be the same as a burnt plug wire shorting against the exhaust manifold.

 

[Joe Dirt]

Would that be constant though, and not affected or dissipate and get quieter as the engine warms up?

Just asking out of curiosity...

 

[dreddog47]

Would that be constant though, and not affected or dissipate and get quieter as the engine warms up?

Just asking out of curiosity...

it definately never goes away. Also, the noise was more audiable when i moved my ear towards the plug, when i moved it towards the Y pipe, i heard it less.



the rythmic tap tap tap noise seemed to match the spark pluses i was seeing. Hopefully its as simple of a fix as swapping a plug.

 

[corkey]

the ticking you are hearing is the arc.
you should be able to hear it with the hood closed too , it can be loud,,

 

[dreddog47]

the ticking you are hearing is the arc.
you should be able to hear it with the hood closed too , it can be loud,,

I can hear it inside the cab driving at 70mph

 

[dreddog47]

I replaced the plug, but I still see it... I guess the wire will be the next thing to replace

 

[Joe Dirt]

Does it get louder if you're under heavy acceleration?

 

[dreddog47]

Does it get louder if you're under heavy acceleration?

I can hear it over the sound of the engine

I'm starting to think that maybe the manifold is cracked, this sound still exists even when the wire isn't arcing out....

 

[Joe Dirt]

That's why I was wondering if the noise is noticeably louder when the truck is cold, or when you step on the gas... Usually the manifolds or leaky gaskets create problems more when the truck is cold until things warm up and expand. I could see it being a wire if it was a constant volume, and no matter the temp of the truck...

 

[dreddog47]

well i replaced the plug wire, and it doesn't arc out anymore... The ticking has gotten alot quieter, cant hear it at idle, but when the RPM's start to go up it comes back... I'm betting the manifold is cracked somewhere as it looks horrible

 

[FarmTruk]

are you using dielectric grease inside the plug boots?

I'd think that could help prevent arcing from the wire to the head.

 

[dreddog47]

are you using dielectric grease inside the plug boots?

I'd think that could help prevent arcing from the wire to the head.

yes I used it, but its NOT arc'ing out anymore, the tick is something else, I'm sure its the manifold since those are so common to crack