If your Impreza/WRX rocker covers are leaking oil (even if it’s just a couple of drops a day) then it’s time to get a new set of gaskets in there. Thankfully if you have the time and can handle a spanner or two, it is a job you can do at home.
WHAT YOU MIGHT NEED
Now before you start this job, make sure you have everything on hand as it’s one of those jobs where you can’t easily throw everything back in the car so you can limp to the parts store. Here’s a couple of things that helped me do the job in my own driveway in the space of an hour and a half (one side but I was well and truly taking my time)
The gaskets: Best to swing by your local Subaru dealership with your Vin number to find out exactly what you need for your model. For my GC8 I need the main rocket cover gasket, the spark plug gaskets and 6 grommets for the bolt holes.
10mm ratcheting spanner: While you can use a 10mm offset spanner (and you probably will need one for access to the lower bolts initially), a 10mm ratcheting spanner is a huge time saver as there’s not much room to work at all and considering the size of the bolts, using anything else will add a lot of time to your job.
10mm offset spanner: As mentioned above, handy for the bottom three bolts when space is an issue.
Permatex Black: Opinion is divided on what gasket sealant to use, I used Permatex Black without any problems. Other Subaru owners have sworn by Hondabond when putting the new gaskets in their groves, then a line of Permatex on top.
Degreaser: If this is the first time you’re doing this, prepare for a dirty and oil soaked job. There was a fair bit of old oil and grease in Project WRX so it helps if you’ve got a couple of cans of Degreaser to clean up as you go.
BEFORE YOU START
Make sure you identify exactly which side is leaking oil (unless you plan on doing both sides at once). Thankfully only one side of my EJ20 was leaking oil and hopefully the other one doesn’t start before I sell it.
Space is incredibly limited with this job so take the time to make as much of it as you can before you start undoing the bolts. For the side I was working on I moved the battery and washer bottle out of the way as well as a couple of wire clusters. I also tucked the coilpacks well away so they wouldn’t suddenly get in the way during the removal.
While you’ve got the space it’s also a great time to clean that area with some degreaser before you remove the rocker cover.
-Put a rag underneath your work area. While it won’t gush out liters of oil, a little will come out so it’s best prepared to have a rag in place, especially so oil doesn’t fall on the exhaust heat shield and have to burn off later.
-Enroll a mate to hand you tools, help line up the cover again and fetch you beer.
-Only finger tighten the bolts. Don’t force them. You really don’t want to snap/break something down there.
THE JOB ITSELF
Once you’ve cleared some space and taken out the bolts, you can slowly pull the rocker cover off. The old gaskets might still be in the rocker cover or stuck to the side of the block. Peel them away carefully. Check the mating surface to make sure there’s no old gasket bits stuck in there (otherwise a new seal won’t be created properly and you’ll have an even bigger leaking oil problem).
Once out, clean the cover with mad abandon – the more you work on this the better chance you’ll have of a clean surface for the gasket to sit in perfectly. Pay particular attention to the grooves so the gasket can go in there smoothly.
While there’s areas the manual suggests you put sealant (namely the cam section), I put a line of gasket sealant along all of the gasket just to be sure. A line of sealant on the bolt grommets isn’t a bad idea either.
Carefully pop the cover and new gaskets back to the block (do it slowly and carefully, you don’t want to jostle the gasket out of place otherwise you’re leaking oil problem will continue..) and then put the bolts complete with new grommets back in. Again there is no need to rush as the sealant will need time to harden and create a proper seal.
I did mine on a Friday night and left everything (ie Battery and washer bottle) out overnight so that I could tighten again if need be and monitor for any leaks. While I did see a few drops of oil on the rags below, it turned out it was residual oil from the oil leaking before. I got under the car and cleaned the whole area with more degreaser and thankfully everything is now leak free.
After 24 hours I put everything back in and ran the car for a good ten minutes to see if anything was happening that shouldn’t. Thankfully no leaking oil, nothing frying on the heat shield and all systems go!