spark plug problem

[BobHyatt]

We put Champion plugs in our 2000 4.6 a couple of months ago. Last night, it started running rough, acting like one cylinder was mis-firing. I unhooked each coil and when I got to #8 there was no change. We pulled the plug and the center electrode is missing, apparently coming loose and dropping down into the combustion chamber...

A couple of questions:

(1) is this tip magnetic so that we might fish it out with a magnet on a flexible stem?

(2) since I have never seen one of these things disassemble like this, even after years of drag-racing, what is the potential for combustion chamber/valve/piston damage?

I suppose we will probably go ahead and pull the head to see for safety, but I thought I would ask if anyone had seen such an issue. I will probably take this up with Champion as well as this seems like a ridiculous failure that is clearly a faulty plug...

 

[streethorse]

If you are lucky maybe it went out the exhaust valve.

 

[BobHyatt]

If you are lucky maybe it went out the exhaust valve.

Unfortunately, I have not won any lotteries recently either, so I am not sure "luck" is on my side most of the time.

I have fished around with a magnet and could not find anything. New plugs and it sounds fine although I intend to inspect again. Can't see any damage on the bottom side of the piston which I can see thru the plug opening, but a bore scope would be nice...

 

[twogts4us]

Your problem started when you installed Champions...
Bore scopes aren't too expensive anymore - make friends with a local engine builder and offer em a few bucks to use or let them take a look for a few more bucks. Likely it was discharged out the exhaust by now or all sorts or noise would have been heard.

 

[wohorsy2002]

Consider yourself extremely lucky if it came out somehow. I have a friend whose porcelain chipped off the side of a plug.... amazing how such a small piece can beat the ever loving hell out of a piston!

 

[the98stang]

No way of telling what damage has been done with out pulling the heads first.

Might as well pull the heads, resurface, and get a nice new head gasket in there.

 

[Mustang5L5]

Motorcraft plugs > *

 

[BobHyatt]

we pulled the head for safety, zero damage. Only drawback to doing this is 40 bucks for new head bolts and about the same for a new head gasket. This is a completely stock 4.6 in a 2000, except for 3.90 rear end and an electric water pump which lets us run with no serpentine belt at the track. Running consistent 13.40's with a best of 13.20 in the 1/4 mile.

Just replaced the clutch and did a tranny check as we were unable to shift into reverse at all, and 5th seemed a little reluctant at times. While we had the tranny off (Tremec on the 2000) we pulled the rear half of the tranny case off and reverse looked brand new. We then pulled the bellhousing/front cover off and while doing so noticed a torx bolt in the side of the tranny that had somehow backed out about 1/4". When we pulled the front cover/bellhousing off, I noticed this was simply a pivot shaft for the internal shift linkage, and as it backed out, it was screwing up the shifter. Took some playing to get it to go back in easily as it wants to bind against the shift linkage if you are not careful. A dab of loctite and shifting now works perfectly.

hard to say whether it backed out by itself or the previous owner thought it might be a fill plug and backed it out himself. It is on the driver's side, about 1/2 the way up from the bottom, about the same distance back from the front end of the tranny. Always worth a look to make sure yours is not backing out. If it is, you need to have someone sit in the car and wiggle the shifter while you screw this bolt in _by hand_ until it bottoms out. Then torque it down and all should be ok.