09 WRX P-301 code head gaskets?

Hey Gang.

Wifes car started to use a wee bit of coolant i noted at last oil change(may be 3 cups).  Toped it off and didn't think about it.  On our weekend trip i could feel a slight shake in the power train...Monday I come home and her cars here my truck is gone.  She tells me is felt like it was running on three cylinders. i asked is check engine light on? No.  Plug in and check the pending codes got a p-301  cyl one misfire code. so i clear it and go for a ride cold it runs okay but once warm it shakes and is dropping cyl 1.  took out the airbox etc changed the plugs they looked fine no change.  I'm thinking the dreaded head gasket.  Cars got 135,000 on it so what to do....  The coil pack is somewhat rusted but it run okay cold.  might try swapping cylinders but a pain to get at but easyier then pulling the motor.

What gasket brand is the in thing to use these days and what bolts?  Do these heads crack often.

All the local yards say 2200 for a motor one told me 4000 but they re-con it and warranty.  

Thanks for the knowledge.

44

My 09 went through all four coil packs (at different times) between about 120k and 160k miles. A couple of them were extremely rusted and probably weren't even getting a decent ground. It would stumble and get misfires under boost. I also replaced a sensor (I forget what), located on the passenger side near the rear of the head.

In any case, i replaced the bad coils with some cheapo ones I got online (made in China) and they worked fine. They were like $60-75 for a set of four. They're really not that hard to do once you figure out the angles and what length wrenches to use. The rear driver's side is the worst, you just need to pull the battery out and use a couple 3/8" u-joints and extension for your socket and you'll be good to go. For the driver's front one you need to remove the little plastic snorkel/tube thing there, which is pretty easy. 

Anyhow, I'd try that first.

Other culprit I had right around that miles with mine is the turbo inlet boot disintegrated at the end it attaches to the turbo and was collapsing under boost and causing a major leak. To replace it with OEM you have to pull off the IM/fuel stuff. There is a Perrin intake boot that, with some cursing, you can install with the IM in place, which is what I used. 

135k miles is about when I started the constant chase of problems on my 09, which otherwise had run pretty damn perfectly up until then. The last couple years of ownership was just one little thing after another until I unloaded the car at 170k or so..

also check for leak at the hose going from the intercooler to the IM (driver's side, below the BPV). those are known to slip off/deteriorate and cause air leaks as well. I think I replaced mine as well.

If you have a head gasket causing a misfire, they misfire for a few seconds after a cold soak from a hot shutdown.

Any evidence of carbon tracking down the porcelain of the old #1 plug?

Swap coils 1 and 3 (or 1 and 2, I forget how Subaru numbers cylinders) and see if the misfire moves with it.

In reply to Knurled. :

yup the plan is to swap coils and see if it moves cyl.  I did order 4 coils but there a week out with the holidays.  Plug from 1 was just a tad darker then #2.  I tried to look at the live data on my harbor freight  "ABS pro" but i could only find the O2 reading and it was bouncing widely with the misfire i had nope to see fuel trim for bank 1 to see if trim drop as the water separated. I'm going to find some anti freeze tester as well see if it has exhaust gasses in it

Turbo Subies don't often pop the HG's. In fact the fix for NA ones is to use the OEM turbo HG's, in place of the NA ones.

Keep looking for other issues before you settle on this.

oh one other thing - check the ground wires from the block to the chassis. About 2 years ago mine had corroded and broken off and i was getting some weird electrical symptoms and random misfires. Once I replaced them, everything was fine again. 

Pulled the coils to swap them and looking at the #1 coils rust on the laminations I said screw it and ran up to AZ and picked one up (I've got 4 NGK's on order) It's run okay again!     When the 4 coils get here i'll change the other two plugs and do all the coils.  

What a load off the mind...  

Nice job on the repair.  Glad it wasn't anything more costly and involved.  I had a slight stumble in my '07 Legacy GT spec. B that started showing up at random at about 135k.  I never investigated it further and sold the car a few months later.