compression gasses escaping around preheating plug in a Diesel vw vento?

[ardong241]

i have a 1996 vw vento 1.9 diesel it is leaking compression gasses around the first preheating plug i tried to tighten it up a bit more but it is as tight as it can go so i made a copper washer to go around it at the heating element side put it back into the engine but it is still leaking gasses can anyone help.

 

[RoberteeL]

you have to re tap the hole to make sure the threads are not damage or use a helicoil