glow plug thread pitch/size

[brokeasajoke]

Was pulling glow plugs and checking glow on each one and discovered the PO had not screwed one completely in for reasons unknown. Now the threads in the head are full of carbon and glow plug wont seat. The gp threads look good as well as head. So what thread is the gps. Was going to chase the threads with a tap after i put shaving cream in hole then vaccum it out and disable fss and blow it out.

 

[JSVD]

pretty sure it's metric - 10X1.0

 

[OLDBULL8]

/\ /\ /\ That's correct above. Be very carefull with the tap, the GP seat has a taper, if you scratch it the GP may not seal. Your best bet, try this first, soak the hole with PB blaster a few times, then use a brass brush like a 22 Ga. rifle cleaning brush or something similar.

Edit: That little bit of carbon that gets down in the precup won't hurt anything, it'll just blow out.