Changing spark plugs - : Jeep Wrangler JK Forum
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post #1 of 6 Old 05-07-2017, 09:39 AM Thread Starter
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Changing spark plugs

Hello everybody! I was changing spark plugs to my JK Unlimited 2007 few moments ago and I had to stop it at first plug. It feeled tight but I guess sometimes they are. Passenger side nro 1 spark plug did something that never happened to me, it snapped and part with threads are still in cylinder head! I couldnt believe my eyes when I was looking that poor spark plug. Any ideas how I can get that part with those threads from cylinder head without tearing upper engine apart?
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post #2 of 6 Old 05-07-2017, 10:35 AM
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I am guessing that the porcelain came out with the broken part. So you are looking at the threaded part only? You can see into the cylinder? The old magnum engines used to do this all the time. I would heat the spark plug part with a torch, let it cool, heat it again, let it cool then extract it with a easy out. You want to heat the spark plug portion only, not the head. The expansion rate would cause to to break free. Some guys would heat it then soak it with penetrating fluid, you could try this if you want.
If the plug is snapped in half, you can't see inside the cylinder, I would remove the head. By the time you were done extracting it you would have a lot of debris in the cylinder.
This is a common problem for newer Ford trucks. Your local parts stores sell tools for this, youtube it.

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post #3 of 6 Old 05-07-2017, 10:55 AM Thread Starter
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Thanks for fast reply! Porcelain came out and only threaded part is jammed in head. I put some penetration fluid around one of the drivers side plug and let see does that plug come out in one part. If that plug breaks too I guess its wisest thing to remove heads and it is quit big job when You are concerning changing new spark plugs! If it doesnt break Im going to try those things You suggested. Thanks!
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post #4 of 6 Old 05-07-2017, 04:20 PM
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If its only the metal threaded part in the head get a proper spark plug socket. I have a nice set from Stahlwille. They are magnetic and work great. make sure the socket is fully seated and it should turn right out.
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post #5 of 6 Old 07-06-2017, 11:28 AM
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There is a buildup of carbon and rust on the threads that were exposed in the combustion chamber.

Go get a nice plug socket. I like the one with the u-joint built in for the back cylinders.

Crack it loose, then unscrew until it feels like it is tighening up again. Spray penetrant. Screw it back in. Unscrew it again until it feels tight again. Spray penetrant. Screw it back in again. Repeat.
Each time you'll get it backed out a little farther. Patience is important. No matter how long it takes, it will be less than pulling the head just to get a plug out.

Sure these fancy-pants spark plugs are good for 100,000 miles and all, but consider changing them more often to make future plug swaps easier on you.

P.S. I just noticed your handle. I have a civilian 1947 CJ2a.

Last edited by rudycon; 07-06-2017 at 11:30 AM.
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post #6 of 6 Old 07-13-2017, 02:39 PM
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A proper spark plug socket is an absolute necessity.

When removing old plugs, you want to keep "downward" (i.e., toward the plug) pressure on the tool to keep it from slipping off. It sounds to me like your socket slipped off the plug while you were pulling on the ratchet/breaker bar, and broke the porcelain.

A couple of good taps on the breaker bar has always worked for me to break the plug loose -- but don't overdo it. These are aluminum heads, after all. Once you break the plug loose, do as others have suggested if you encounter resistance: 1/2 turn to the left, 1/4 turn to the right, 1/2 turn to the left, and so on.

Before you install your new spark plugs, put a small dab of anti-seize compound (I've always preferred the copper stuff) on the plug threads. This will prevent the plug from seizing in the head. After a couple of heat cycles (100-200 miles), I always re-check the torque on my plugs.
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