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Keep cracking plugs on cylinder 5

B

Brick on Wheels

New member
Guys, I keep cracking the porcelain on the #5 spark plug. I've cracked 3 now, and only got 100 miles on the last one. Any idea what is causing this? I'm not beating on the car at all, driving like a grandpa trying to get max economy. Plugs are Delco 41-101. Electrodes are fine, it's just the porcelain. Tried to upload pics to this site, but it says they are too big.
 


Are you using an actual spark plug socket to install them? That's the only way I've seen one get a crack in it. Is there something near that plug that could hit it?
 
Yes, using a spark plug socket. None of the other plugs are cracking. You can tell when it has cracked, as the mileage will drop off and the car will stumble bad on throttle tip-in (like going up a hill and seeing a couple lbs of boost build in 4th gear).
 
Is there anyway it's hitting something? Being #5 it's right up front. Do you have bad motor mounts, maybe the fan?

I too can't see why a plug would crack on it's own unless it's getting hit
 
No, if you look at our motors, the plugs are set back in the manifolds so they are mostly protected from hits. I just pulled the plug back out, and it has no cracks in it. Very carefully put it back in. Will post back if it happens again. Thanks for the replies.
 
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