: cracked spark plug



Greg Thomas
08-18-03, 10:01 AM
96 Deville
Northstar
120,000 miles

The #7 plug will run for about 2500 miles then start missing. When removed the porcelain part will have a vertical crack. A mechanic has changed it twice and I have changed it twice. I am quite certain that we are putting them in without breaking them. It has less than 3 months on a new set of GM plug wires and I use GM plugs. What could cause this?

Katshot
08-18-03, 01:49 PM
Never heard of anything that cracks the plug besides physical contact with something else.
There was a guy here a while ago that had the same problem. I don't recall what ever became of him or whether he ever figured out what was causing his problem. Try doing a search here on the cracked plug and see if you come up with anything.

AKPsiMC03
08-18-03, 04:42 PM
when i changed my eldo plugs 2 of them were like that. I asked an engine builder and he told me it was from excessive heat around the ceramic of the plug.... i still dont know what caused it though.

Logandiagnostic
08-23-03, 03:34 AM
when i changed my eldo plugs 2 of them were like that. I asked an engine builder and he told me it was from excessive heat around the ceramic of the plug.... i still dont know what caused it though.


It feels like a crack but its not. Its carbon tracking. Once you have carbon tracking on a plug/boot setup, it will keep coming back over and over. Replace both the plug and the spark plug wire.

Logan

Greg Thomas
08-27-03, 01:33 PM
It feels like a crack but its not. Its carbon tracking. Once you have carbon tracking on a plug/boot setup, it will keep coming back over and over. Replace both the plug and the spark plug wire.

Logan

Logandiagnstic, You hit the nail on the head. Thanks. I checked out the plugs that had "cracked" and the would clean up with a wire wheel. So I guess I got a bad plug wire boot. Can you buy just one GM wire? I hate to give another $150 for another set. I doubt if GM would warrant them since they have been on about 3 months.

Thanks Again, Greg

elwesso
08-27-03, 07:41 PM
You should just be able to get one......