My #5 spark plug boot keeps popping off after a short amount of driving.

Is this a normal occurance after changing plug wires? I'm hoping it's just moisture inside that's heating up and causing it to come off - but could there be leakage from the combustion chamber through the threads? Anyone ever experience this?


Thanks,
-Ben Allison

 

Could be either the adhesive that bonds the insulator to the metal part of the sparkplug is leaking or the sparkplug is incompletely installed or crossthreaded. One other possibility is a cracked head. Hope it's a bad plug.

Dennis

 

Too warm to retain moisture, so either the plug is not sufficiently tightened, or in rare cases, I've seen a plug insulater not seal to the metal body. Pull #5 wire, start up on 7 cyls, and place a length of hose (stethoscope) in the well to listen for escaping exhaust. - or simply, try a spare plug.

 

When removing the plugs, I noticed the #5 (and one or two others) had oil on the threads of the spark plug - is this normal? I'm suspicious because not all of them were like this.

 

Maybe you're not getting the wire fully clipped onto the plug electrode. Or that is loose.

Oil on the threads could be coming from the outside. I'd look at the face of the plug as to whther there's excess oil in the chanmber. Yellow or golden is fine. Black and caked-up is bad.

 

Ben,

Oil on the threads is AFAIKT unlikely to come from the cylinder - oil in the sparkplug hole on the other hand (leaking through a bad cam-cover seal) would run down the thread when the plug is removed. Is there oil anywhere else on the plug?

I had this on all 8 plugs a year ago - I had the seal, and an army of O-rings, replaced which solved the problem. (PO had just tightened the bolts when it first started leaking and squashed all the O rings).

It's an easy fix, took a bit of time, but at least they're relatively cheap parts .