So i have a customer with a 2000 nissan sentra. Every now and then he gets his plug in cyl 1 and 4 spark plug electrode thing pushed down to the tip. However, i dont think the piston is touching it because i looked down the hole, i do not see any marks on the piston and also, on the perimeter edge of the plug, it looks beaten up. What can cause this to the plug? Detonation? I checked the part number on the plug, its the correct one.

Can someone help me out please. thanx

 

If it were detonation, the electrode or grounding strap would start to be consumed.

Only thing I know of that would cause this is contact.
Sure plugs are correct length?

tom

 

smashed rod bearing can cause contact, but you would hear it first in the bottom end lol

 

So where do i even start with this. I never dealt with a car like this so idk what to check first. and lets say the rod bearings were bad. In that case, it would happen all the time. This only happens under load. When the car is idling, the plugs are fine, but when you drive, the 1st and 4th plugs get smashed in. I dont understand.


and the plugs are the same length as oem.

 

You wouldnt see a mark on the piston because it would be covered with black soot almost immediately. I would say its the piston hitting it though.

 

on piston hitting. Or, plug was tightened down too hard. Still have a washer on it?

 

Ya the washer is still on it. SHould i put another washer to space it out a little more or would that harm anything?