2nd time in less than a year broken spark plug

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goat69
Posts: 12
Joined: Sat Mar 29, 2014 6:11 am

2nd time in less than a year broken spark plug

Post by goat69 »

Back in January 2021, I replaced a spark plug that had the electrode completely broken off and was causing misfire in cyl #2. I replaced it and it ran great once again..OH.. and this is on my 2006 Vibe. Yesterday, 6/16/21, that same cyl #2 spark plug electrode broke off again. WTH? It seems as though the piston is coming up to high and breaking off the electrode. Is this a safe assumption? Or, has anyone else experience this. This is on my 152K mile engine.
zbyers
Posts: 1767
Joined: Thu Apr 03, 2014 6:12 pm
Location: Sheffield, Pennsylvania

Re: 2nd time in less than a year broken spark plug

Post by zbyers »

what brand plugs? where did you get the plugs? what kind of shape is the coil in? wouldn't the cam be more likely to hit the plugs?

post a pic if you get a chance.
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andrewclaus
Posts: 482
Joined: Tue Oct 03, 2017 6:38 pm
Location: Golden, CO

Re: 2nd time in less than a year broken spark plug

Post by andrewclaus »

Beside the obvious misfire code, have you been reading any other diagnostic codes?

Did you lose the ground electrode, the center insulated electrode, or both?

I heard of severely worn crankshafts, connecting rods, and wrist pins leading to a cylinder hitting a plug, but you'd probably be having other audible problems with that much engine wear. A severe detonation might break a plug. Or the improper plug was installed.
jolt
Posts: 945
Joined: Sun Mar 02, 2014 2:07 am
Location: Twin Cities, Minnesota

Re: 2nd time in less than a year broken spark plug

Post by jolt »

Can you post a picture of the spark plug tip that goes into the cylinder and of the top where the name and part number of the plug are? Is it the center electrode that is been damaged or is it the grounding strap on the plug? Amazon and Ebay are said to sell counterfeit / gray market spark plugs and this could be poor manufacturing of the plug itself.

If the grounding strap is been hit by the piston, and it had no history of doing this years ago, something has changed. The piston should not be that close to the spark plug. If a rod bearing or wrist pin is loose in the engine it could allow the piston to hit the spark plug but you would have other loud noises coming from the engine. Does the engine make any other noise when running? Has the cylinder head been off the engine? Was the head resurfaced or block resurfaced?

To test for a loose piston, you can take a long piece of wooden dowel rod and stick it in the spark plug hole on to the top of the piston. Mark on the rod it's location in the cylinder head spark plug hole. Now slowly turn the crankshaft back and forth by hand and watch the dowel rod's movements. There should be no delay, the rod should move with even the slightest crankshaft movement as the crankshaft is rocked one direction and then the other. NOTE: Make sure that the dowel is way to long so that it can not fall down into the cylinder or you will be pulling the head off to get the dowel rod out.

Do you have the right part number spark plug installed? A extended tip spark plug installed in a engine that is not designed to use such a spark plug, can have the piston hit the plug.

Take a bore scope and look down in the cylinder. You can find cheap bore scopes that can hook to a cell phone. If the piston is hitting the end of the spark plug ground strap, you should see the marks from it left as dents in the top of the piston. Also check for carbon build up on top of piston.
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