Spark Plug Complications

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Recently I found some loose spark plugs in my engine. They were all cleaned and re-tightened. There was a mysterious odor that led me to discover this problem in the first place. At least that has been corrected. However, I feel that something is still not right with my engine. Gas mileage is still down, and I have a slight difficulty starting the engine when it's hot.

Could the head have been damaged by the loose spark plug condition? Or perhaps the spark plug itself have developed a crack? Could an exhaust leak cause any of these problems?
 
I would first check that you have the recommended spark plugs in the engine. I doubt very much that the cylinder head was damaged but, you may have damaged plugs i.e. cracked insulators or fouled with oil/fuel. Why not just put a new set of spark plugs in and maybe a new set of ignition wires at the same time.
 
None of the plugs appeared to be damaged or fouled. The loose ones were all charred up before I cleaned them off. They appeared to be in decent shape otherwise.

Would a crack or damaged plug be pretty noticeable? Or could there be a fine crack that is hard to see? The plugs I have now are NGK's. The car originally came with a set of Motorcraft plugs.
 
I would replace the plugs with what came in the car originally. If the car is older then I would replace the ignition wire also.

I would imagine that a crack could be very difficult to see in a plug.

Go get some Motorcraft plugs!!!

Good luck
 
A cracked plug can be very hard to see. I have a 1967 john dear lawn tractor that had a plug with a cracked insulator. I just couldn't get the thing to run. Was about to put a new condenser and points on it.
Any ways the ceramic insulator around the electrode had a crack in it. I had taken this plug out before and looked at it and well it looked okay. The only way I found the crack was grounding the plug to the engine and watching a spark. I was luckily able to see the spark traveling to the base of the plug along a crack I couldn't even see.

Long story short if in doubt throw a new plug in.
 
Would a cracked plug explain difficulty in starting? Or bad fuel mileage? Can gases escape through a cracked plug?
 
Additionally, if a sparkplug is not tight heat cannot effectivly transfer from the plug to the block perhaps overheating the plugs. Far fetched perhaps, but in any event I would change the plugs and wires as mentioned by some others. Cheap enough to do.
 
I just read your last post in your other thread. I would've never dreamed that fuel vapors were coming out of the spark plug holes; what did you use to tighten them with initially?

I use a bent handled flexhead ratchet; which is about 11'' long; as hard as I can pull on it.
 
The vapors were more like fuel and exhaust combined. Spark plugs were my last guess as well, but as soon as I tightened them the smell went away.

The directions in the NGK package said to thread the plugs down to the seats, and then torque an additional 1/8 turn. That's what I did, but apparently it wasn't enough. I had also used anti-seize which I skipped this time. This time I tightened an extra 1/4 turn.
 
How did you clean your 'charred' plugs?
Without a sandblaster, it can't be done properly. If you used a wire brush, the metal will impregnate the ceramic and you will never get it out, and they will misfire.
 
Well, here's the deal: I've got some OEM plugs in hand, and I'm going to work on the car right now. So hopefully I'll have some answers by this afternoon.

Mechtech, I did use a wire brush because I was unaware of that happening. Thanks for pointing it out.
 
The new plugs are in. My car seems to be healthier, but it may take a few days for me to safely conclude that.

For now, it's picture time! Everyone likes pictures right?

http://i6.tinypic.com/87b9dnm.jpg
Notice anything unusual above cylinders 2 & 3?

http://i1.tinypic.com/8byot1v.jpg
Here are the plug coils from when I first discovered the problem.

http://i11.tinypic.com/6lvnpyo.jpg
Leaky plug vs tight plug.

http://i8.tinypic.com/73dnipg.jpg
After being cleaned, re-installed, and removed yet again.

http://i1.tinypic.com/6x0kx8l.jpg
This is the closest thing to a crack that I found on any of the plugs.
 
Last edited:
Your plugs weren't tight at all! If they are crush washer type, tighten them by hand until they are snug to firmly tight/ie the gasket is crushed all the way. This "usually" ends up at about a half turn AFTER you thread them in by hand and the washer hits bottom. Very noticeable; you thread by hand and it turns very easy and then stops. Attach your ratchet and firmly snug them up until you can no longer turn with light medium to medium force. DONE.

If they are tapered seat plugs like most domestics use then it only takes about an 1/8 of a turn with medium force to tighten them. If you only go an 1/8 of a turn with a gasket seat type plug, then ye, you're losing major compression.

Go by feel IMO.
 
I looked it up, yours has tapered seat without a gasket so you're right, it should be about 1/8 of a turn. But even if you get to 1/8 turn and it's till doesn't feel tight, just snug it up till it's tights with light moderate force.
 
The new Motorcrafts definitely felt tight. Even hand-threading them in felt like they were more snug than the old NGK's. So that was reassuring to me in some way. There's no way these will back out like the NGK's did.

So what does the yellowish discoloration on the ceramic indicate?
 
Believe it or not, you can "knock" them loose. It's doubtful in your case but I've experienced extreme detonation and had 6 loose plugs.. and two blown headgaskets. The discoloration on the ouside of the plug is normal. My TL had a trace of carbon on every plug and the reddish/yellowish tint on the outside. I compared it to pictures of others and concluded it was normal.
 
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