3.0 why spark plugs are cracked

[elkhunter338]

View attachment sparkplug.pdfI heard what sounded like a bad spark plug wire.
Engine was not running rough. Pulled the spark plugs out and the porcelain under the spark plug wire boot had a long vertical crack.
Part of the plug inside the cylinder looked normal.
What would cause this crack. 2 of the 4 were cracked.
It is the correct plug. The only thing I can think of is I put them in too tight. Torque setting ? I put them in with no torque wrench.
2007, 3.0 GM

The attached file is what mine look like but these are not plug out of the boat, just a real good picture of what happened to mine.

 

[Bondo]

Re: 3.0 why spark plugs are cracked

Ayuh,... Generally, it's caused by not keepin' the socket straight in line with the plug, when tightenin'...

 

[elkhunter338]

Re: 3.0 why spark plugs are cracked

That is kind of what my research on the internet is leaning towards. My plug socket has a real tight rubber insert which could put some side pressure on the plug.
No signs of running too lean or spark knock because the plug shows no signs of blister and no broken or weird looking end on the part that is in the cylinder.

 

[Oshkosh1]

Re: 3.0 why spark plugs are cracked

Happens more frequently with the articulated sockets also!

 

[brnschoneck]

Re: 3.0 why spark plugs are cracked

id jsut change them be carfull putting new ones in maybe use a torque wrench ...fire her up and see how she runs ...

 

[Hoosmatroos]

Re: 3.0 why spark plugs are cracked

When I discover a cracked plug I always hold my compressor ready. Before removing the plug, clear the hole with some compressed air so there can't fall ceramic pieces in your cylinder.

 

[Oshkosh1]

Re: 3.0 why spark plugs are cracked

When I discover a cracked plug I always hold my compressor ready. Before removing the plug, clear the hole with some compressed air so there can't fall ceramic pieces in your cylinder.

A shop vac works also...
I've used small rubber tubing and duct tape to reduce the size and allow for entry into hard to reach plug wells to suck out dirt/debris prior to plug removal.