[lewis17]

i went down to the local auto parts store,and bought four new H-12 champion plugs, got all of them replaced except one. the one i pulled out was a champion H-12 plug, but the threads were bigger than the rest of the H-12 plugs....so three are new plugs and i cleaned up the old and put it back in... any one got an answer! thanks

 

[Grand Valley Tractor]

I would guess a simple case of somebody at the factory mismarking the product, or, if the threads are just slightly oversized it could be the threading die didn't close all the way before rolling the threads...it happens, unfortunately.

 

[JohnW]

Quality control :thSick:

 

[rscurtis]

That cylinder could have had a thread repair performed in the past and the insert came out with the plug.

 

[lewis17]

That cylinder could have had a thread repair performed in the past and the insert came out with the plug.

well it still has threads in the head, and the threads in the head are fine, but the hole is bigger than the other three...and everyone of them have H-12 on them.... when you match up all the h-12 plugs they all are the same except the one...so in order for me to replace it.. it has to have bigger threads...but all the H-12 plugs that i have looked at have smaller threads

 

[Tractor-Holic]

I agree with rscurtis,a heli-coil was installed previously and it stayed on the plug,instead of staying in the head--the head still needs threads to hold the heli-coil in it,so yeah,it'll have threads in the plug hole..

If the insert wont come off the old plug,just take it to a parts store and buyt another instert the same length and thread,and screw it on the new plug and install it..I had this happen to me on more than one VW Beetle I owned,its common to find heli coils on their spark plug holes in the heads,they stripped out easily..

 

[lewis17]

I agree with rscurtis,a heli-coil was installed previously and it stayed on the plug,instead of staying in the head--the head still needs threads to hold the heli-coil in it,so yeah,it'll have threads in the plug hole..

If the insert wont come off the old plug,just take it to a parts store and buyt another instert the same length and thread,and screw it on the new plug and install it..I had this happen to me on more than one VW Beetle I owned,its common to find heli coils on their spark plug holes in the heads,they stripped out easily..

ok... i see what you mean now... thanks so much!

 

[JohnW]

i went down to the local auto parts store,and bought four new H-12 champion plugs, got all of them replaced except one. the one i pulled out was a champion H-12 plug, but the threads were bigger than the rest of the H-12 plugs....so three are new plugs and i cleaned up the old and put it back in... any one got an answer! thanks

Yeah I completely missed the part about it being an old plug with the larger threads. The others being sharper of eye and mind have got it right. The heli-coil repair just unscrewed from the head. Replace it with a new one and all will be good.

 

[lewis17]

Yeah I completely missed the part about it being an old plug with the larger threads. The others being sharper of eye and mind have got it right. The heli-coil repair just unscrewed from the head. Replace it with a new one and all will be good.

thanks it unscrewed easily and i got the new one in