Working on 09 subaru legacy 2.5 sohc and pulled these plugs out. What can you tell me about them? I dont know when they were replaced last. Both valve covers have signs of slight leaks around boot gasket. Cyl 3 has history of misfire(thought it was because fuel injector-not sure if a code told me that)
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number 4 seems to be worn more than the rest for some reason. maybe they couldn't get to it for some reason on the last plug change. no idea on what the gunk is. it doesn't really look like there was oil contamination. its possible that they were only finger tight and combustion was blowing past the threads and washer a bit.
Any chance this is caused by plug boot gaskets on the valve covers? #3 just recently started seeping and it is on passenger side, same as #1
Leaks on #2 and #4 have been going for a while.
Yet, #3 had worst gunk built up
Its possible. Were the spark plug wells full of oil?
Not full, #1 had as much as #3- very little in those. The other two were a little worse... could a head gasket leaking antifreeze do this at that location?
No, at least, not on the 2.5
Any other guesses of what that gunk between washer and hex could be? It almost feels like clay/mud, somewhat gritty
Edit for ommitted info; gunk on plugs 2,3, and 4 between washer and plug looks/ feels almost like clay, rusty color. Plug one had no gunk
The gunk you're referring to is probably old antiseize that is supposed to be out on for installation. As another comment mentioned, #4 is more worn than the others. This is because of the way the wasted spark ignition system is designed, not because it wasn't replaced. Typically, #1 and #4 wear faster than #2 and #3.
As for a misfire, I don't usually see issues with fuel injectors on the NA cars. So it's probable that it's either ignition related (plug, wire, coil pack) or you have a tight valve, which means the valve cover has to be removed and the valve lash adjusted.
Thanks for your insight!
Those are spark plugs for sure.
https://www.reddit.com/r/MechanicAdvice/comments/jiihfx/before_you_post_your_spark_plugs_take_a_look_at/
The gunk that came out is between spark plug washer and base
Could this have been from an oil stop leak additive?