Hello all, I have a 2007 Prius with 210k miles. It has no problems or symptoms. I just changed spark plugs and now have concern for a bad head gasket. I previously changed them myself at 115k. At that time, I used anti-seize on the threads. I have since learned not to do that. The plugs didn't feel great coming out, but they did make it out and the excess anti-seize didn't seem to be causing too many problems so I went ahead with the job until I got to the last cylinder (driver side). That one had the most anti-seize by far. The area immediately above the threads was gunked up by it. You can CLEARLY see the stuff at the tip of the coil is anti-seize so I'm not worried about the tip. My concern is near the middle of the coil with all of the brown film? Seems like oil? Inside the well you can see there is discharge/gunk on about 1/3 of the circumference. I cleaned everything back up and re-installed because by the time I got to #4 I was just expecting a little funkiness from the anti-seize but now I'm second guessing myself... Priuschat detectives - what's the verdict? p.s. running an oil catch can for 80 or 90k miles will eliminate the oil in the bottom of the throttle body. Not sure if the debate about the source of the oil being from the PCV or Atkinson cycle is still alive, but I think this just about settles it.
You must mean valve cover gasket not the cylinder head gasket. Looks like you need a valve cover gasket and the spark plug o rings maybe but even so it's pretty clean I don't think the one NZ really has head gasket issues they may fail it really high mileage but then anything can fail but these aren't known for it I don't believe.
It does look like oil residue from a very minor valve cover gasket seep where it seals at the spark plug bore. Unless there is oil residue from seepage along the outside of the valve cover, I would leave it alone. If you want, pull a coil in a year or two and see if the seeps have gotten worse. Posted via the PriusChat mobile app.
nothing to be concerned about, the oil seepage is very minimal. If your spark plug is drenched with oil and causing misfires then you have to replace the valve cover gasket (not the head gasket) Usually it's oil at the tip of the boot and in the spark plug that you need to visually check.
