There are two things I dislike doing on Subarus: spark plugs and valve cover gaskets. Neither is particularly difficult, they just take a longer to complete than your average 4-cylinder. I can probably do spark plugs on my Bugeye in an hour or so now that I removed/relocated a few items in the engine bay, however, valve cover gaskets always seem to be a weekend ordeal.
The driver’s side is pretty straightforward, as most of the bolts are accessible from either above or below the engine. The passenger side, however, is not so convenient. The bottom three bolts are hard to get to without removing the up-pipe; which means removing the header and the downpipe. I also needed to raise the engine to get the bottom rear bolt out. Good times.
Since the pre-turbo exhaust has about a 100k miles on it, I decided to play it safe and order new gaskets.
This isn’t really a how-to install guide as I just needed to get this done, along with some other things in the area, and I didn’t have time to document the process. Plus, I ended up getting pretty sick towards the end of the process so I didn’t document this very well.
There is a pretty decent write-up here.
Valve Cover Gasket replacement Subaru WRX:
I had planned on painting the valve covers while they were off, but it was too cold (around freezing) and I didn’t have enough time to wait for them to dry so I just cleaned them up a bit so that it would be easier to spot any new oil leaks.
Once the valve covers were off, I could see my cams. And I don’t know why but I expected them to look milder; not that I measured them or anything. Maybe I just haven’t seen Subie cams in awhile.
The insides of the valve covers weren’t great but they weren’t horrible either. I wanted to clean them off, but at this point in the process I was coming down with a pretty bad cold.
So I just replaced the gaskets and reinstalled the covers, along with the IAG half moon seals. EJ207s w/AVCS have their own valve cover gaskets so be sure to order the correct ones. I ordered all of my EJ207 specific gaskets from IA Performance.
The JDM OEM gaskets fit perfectly. They are a little spendy but I didn’t really want to take a chance on an aftermarket set.
A secondary reason for this install was my up-pipe heat shield. It began to rattle horrendously on cold starts. There is nothing more embarrassing than a loud rattle or squeal so I used this opportunity to remove the heat shield and wrap the up-pipe in exhaust wrap. I think in the long-term, I want to use something like Heat Shield Armor from Heat Shield Products; in the meantime, I just grabbed a roll of DEI Titanium exhaust wrap from the local parts store.
Once I pulled the header and up-pipe off, it was pretty clear that I had a leak at almost all of the pre-turbo gaskets. Which frankly, I was kinda glad to see. I have not been impressed with the spool on the EJ207 twin-scroll. So much so that I have been considering switching to a single scroll/UEL setup.
The biggest hang-up for me on single scroll is the weight of the cast manifolds vs the JDM headers and the cost of the switch. I would need exhaust manifolds or headers, up-pipe, turbo, and downpipe.
Also, I’m not a huge fan of the Subie rumble. I think it sounds great in the moment (like when I hear a Subaru driving by), but living with the rumble everyday is obnoxious to me; it just drones like mad during daily driving.
While the header and up-pipe were off the car I decided to weigh them. The pre-turbo exhaust actually came out heavier than I thought. The header came in at 19.8 lbs and the up-pipe weighed 8.7 lbs (28.5 lbs total).
With the heat shields removed, the naked up-pipe weighed 5.9 lbs.
Adding the exhaust wrap brought the weight back up to 6.3 lbs; with an overall lightness of 2.4 lbs. Which is pretty surprising that the heat shields weighed that much, to begin with. I suspect the header heat shields probably weight around 5-6lbs.
By comparison, the UEL OEM manifold/up-pipe weighs around 26 lbs. Although it isn’t clear from that link if the Nasioc user weighed the heat shields with the manifolds. Either way, I expected the JDM headers to be much lighter.
I spent quite a bit of time cleaning up oil off of the heads and old gasket material from the up-pipe, header and heads. The studs actually came out of the passenger side head as they the nuts were seized to the stud. I soaked them in a bucket of PB Blaster. I’m generally not a big fan of PB, but I had several cans from the years so I just emptied the cans into a bucket just to get rid of it.
Also, I remembered seeing a video on YouTube about a guy using a piece of paper or something and some compressed air to show the flow difference between a log header and a equal length header.
I tried that test on my JDM manifolds and it did not suck the paper in like it did on the video. It actually blew back out like the log manifold. Which leads me to believe that the OEM JDM setup does not perform nearly as well as we thought it did; at least not in terms of cylinder scavenging.
However, after seeing the condition of my exhaust gaskets, I was pretty eager to put this thing put back together to see if there was an improvement in performance.
Putting the car back together is more or less reverse of removal. On the valve cover gaskets, you do need to apply Threebond/Fujibond or Permatex Grey RTV in a few areas. Everything else is pretty straightforward.
After driving for a couple of months now I can say the exhaust leaks definitely hurt the performance of the EJ207. Low end response has improved significantly. Driving around town is much easier, I don’t need to wind it out as much as I used to, and I don’t need to downshift nearly as much; although it still needs a 4.444 final drive.
I started this post way back in February; but the semester got under way and then I got sick again so I had to put the blog on the backburner. Now, the semester is over so there will be more posts coming out soon.
Cheers!
B.黒曜石 