Login

How does oil get past plug threads into the combustion chamber

Hi Scotty,
How does oil get past plug threads into the combustion chamber if the tube seals are shot?

Hi Scotty,

How does oil get past plug threads into the combustion chamber if the tube seals are shot? Plugs are tightened down pretty good and have those crush washers. I know the oil can get thru bad tube seals, but past the plug threads too? Any assistance is appreciated. Thank you, MarkDIY.

tube seals only make the top of the spark plug oily. But, if you remove the spark plug, then that oil of course drips down to the end of the plug too. If engine has worn piston rings or valve seals, then oil would enter the combustion chamber that way too.

Stories