Plug Oiling

[EJSC4]

Can anyone give me some idea why I have 1 plug(number 3) which keeps oiling up and causing miss fire. Compression is good and after cleaning runs realy well for about 150/200 miles then same problem.

 

[teamzr1]

Can only guess

1. valve seats & guides for #3
2. Oil getting past #3 piston rings
3. is EGR or SMOG system near #3 ?

Maybe need to do a longer time of compression test ?
Slight leak of head gasket by #3 ?
Have you pulled the valve cover for that head, checked the valve parts for #3
and with cover off, used a smoke tester to location a slight leak ?

 

[EJSC4]

Thanks for suggestions I will check those

 

[EJSC4]

Replaced all valve stem seals. Problem solved