Tell me about GC8s!

"1337HPMustang" (1337hpmustang) 09/30/2014 at 21:36 • Filed to: subie quest

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So I have the funds to buy a winter car and I want to import this low mile wrx wagon

http://b-pro.ca/product/1995-l…

After shipping, would be about $5500. Obviously a good price and a good auction grade (probably only reason it isn't a 4 is because of those body scuffs). What do you guys know about the EJ20G? Reliable? What should I expect if this will be a just a commuter?

bob and john > 1337HPMustang 09/30/2014 at 21:37

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beware head gaskets. IDK EXACTLY when they went on impreza wagons (~100k KM), but its an engine-out procedure to get it done.

1337HPMustang > bob and john 09/30/2014 at 21:40

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wasn't it 2.5's with the head gaskets?

bob and john > 1337HPMustang 09/30/2014 at 21:43

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might have been.
At this point, i just say beware head gaskets on a subaru. end of story.

Boxer_4 > 1337HPMustang 09/30/2014 at 22:00

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EJ25D, EJ251, and early EJ253 engines are the ones to watch for head gasket issues. All of them 2.5L engines, N/A, and open deck. Head gasket issues can occur on the semi-closed deck 2.5L engines, and on the 2.0L and 2.2L engines, but it is much less common.

This WRX wagon, being a 1995, has the EJ20G with the Bucket Style HLA. That meaning the valves adjust automatically. The later EJ20G (1997-1998) has Shim Over Bucket Style valves, which need to be adjusted occasionally. Being a wagon, I believe it has the Mitsubishi TD04 turbo. These are good for 217 hp at 6000 rpm and 192 ft-lbs of torque. All EJ engines used timing belts, and the EJ20G is no exception. Try to find out if it has been replaced before. They are typically good for 105,000 miles (169,000 km) or 105 months, which ever comes first. You are good on the mileage, but I'm not sure on the months.

It will probably be just as reliable as any turbo Subaru, which depends on how well it was looked after before. As always, a throughout look over by a garage specializing in Subarus probably wouldn't be a bad idea.

Also, only the sedan is a GC8. While pretty much everyone has adopted that to mean the chassis code for the first generation WRX, that isn't the case. The wagon is a GF8 (as seen on the chassis plaque), while the coupe is a GM8.

Boxer_4 > bob and john 09/30/2014 at 22:04

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EJ25D, EJ251, and early EJ253 head gasket problems are almost always guaranteed by 100,000 miles. For other 2.5s and other Subaru engines in general, its a good thing to watch, but it isn't nearly as significant an issue.

1337HPMustang > Boxer_4 09/30/2014 at 22:45

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Wow thank you for the awesome reply! I knew we'd have a resident subie expert on hand to guide me through this.

So what I understand is the closed deck, which this car has, is the one to have because of something to do with shims and cooling, right? Also since it's an earlier model, the valves don't need to be adjusted? So far I don't see any cause to steer clear of it and I can easily replace the belts if need be when I get it (unless they're trickier on a flat four?).

Boxer_4 > 1337HPMustang 10/01/2014 at 01:01

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I do apologize in advance, I may have accidentally written a book...

Open deck vs closed deck has to do with the amount of material around the cylinder bores in the short block (engine without heads). For Subaru engines, there are 3 main deck types; closed deck, which has the most material, open deck, which has the least material, and semi-closed deck, which is somewhere in between. One of the main causes of head gasket failure in Subarus is from the cylinder bore slightly "walking" back and forth, which erodes the head gasket around the cylinder bores. The more material supporting the cylinder bore, the less it will "walk".

The EJ20G is odd in the sense that there were both closed deck and semi-closed deck versions, but I'll get back to that. This snippet gives a pretty good look at the differences and why Subaru has 3 main deck types:

Summarizing:

The open deck is used on their mass market vehicles due to easy of manufacturing and lower cost to produce. *As an aside, the open deck engine pictured is an EJ253, which does not have the head gasket issue. This is a picture of an EJ251 block, which does have the head gasket issues. It's amazing that Subaru thought they could get away with that little supporting the cylinder bore.*

The semi-closed deck has been used on their performance market vehicles since at least 1993, and still used today, including the EJ257 in the STi. The semi-closed deck is better set up to handle the mild to moderate boost setups that Subaru uses, while still being cost effective to produce.

The closed deck was used in some EJ20Gs from 1992-1995 in WRX-RA models, as well as some WRX sedans until 1994. This was to satisfy homologation regulations so that Subaru could use the closed deck block in their WRC cars. The closed deck could take a lot of boost, perfect for a rally car, but it was expensive to produce. The EJ22G in the 22B was also a closed deck design.

Now, back to the EJ20G. I looked up the engine code for the particular WRX wagon you were looking at (EJ20GDW4NE, found on the chassis plaque), and saw that it is in fact a semi-closed deck engine, not a closed deck engine. For some reason on the website I just linked, they call it an open deck engine, not a semi-closed deck engine. They are using the wrong term. Looking at a picture of the two EJ20G block types, you can see the one on the left is a semi-closed design, not an open deck design (the right is a closed deck block).

The only time you really see an advantage with the closed deck over the semi-closed deck is if you plan on really increasing the boost (30 psi or more is what I've seen). The semi-closed deck is typically plenty strong for most applications, especially for a commuter.

You bring up an interesting discussion point with cooling regarding the deck type. It's a bit of a long discussion, but the short of it is that some people believe that the closed deck blocks don't dissipate heat as easily as the semi-closed deck blocks. It's been a heavily discussed topic on many forums, and nobody really knows who is correct.

Moving on to the valves, yes, the valves on this engine do not need to be adjusted. They use something called Hydraulic Lash Adjusters (HLA), also known as Hydraulic Tappets. Unlike traditional solid lifters, HLAs operate with zero clearance between the camshaft and rocker. Wikipedia has a pretty good explanation:

Oil under constant pressure is supplied to the lifter via an oil channel, through a small hole in the lifter body. When the engine valve is closed (lifter in a neutral position), the lifter is free to fill with oil. As the camshaft lobe enters the lift phase of its travel, it compresses the lifter piston, and a valve shuts the oil inlet. Oil is nearly incompressible, so this greater pressure renders the lifter effectively solid during the lift phase.

As the camshaft lobe travels through its apex, the load is reduced on the lifter piston, and the internal spring returns the piston to its neutral state so the lifter can refill with oil. This small range of travel in the lifter's piston is enough to allow the elimination of the constant lash adjustment.

Regarding the timing belt, I don't think they are any trickier to change than other longitudinal engines. If I remember correctly, the EJ20G is an interference engine, too, so if the timing belt breaks, piston and valve damage can occur.

I don't think I missed anything...

gc8foreva > Boxer_4 10/01/2014 at 10:33

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The EJ20G is indeed an interference engine. All the EJ engines except for the EJ18 and EJ22 Phase I blocks are interference engines.

1337HPMustang > Boxer_4 10/01/2014 at 12:05

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Wow thank you so much for clearing that up. I appreciate more than you know. It's made navigating and reading the forums so much easier. You single handedly dispelled all the negative conjectures I had about subaru engines and I think Im well on my way to buying the car barring some problem that's specific to that car. Since I have to rely on the auction grade, and 3.5 being rather good, I think it's a good price for a good car. One last question, would you buy this car if you had 5 grand for a winter commuter?

MonkeePuzzle > 1337HPMustang 10/01/2014 at 14:03

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ignore the head gasket comments, this engine is before that became a real issue, and it plagued mostly the US delivered 2.5s. Also, if this is a 95 its pre-interferance so it will run even if you let the timing belt melt (from experience you say? yes I done did that... )

melted - http://oppositelock.jalopnik.com/well-thats-a-s…

that bumper has GOT to go.

if its a wagon technically its a GF not a GC, handy when looking for pics to drool over

interior on that looks great, ok paint over the blue. but still, JDM WRX seats and bells and whistles. water sprayer for the intercooler. so cool. and rear spats and such that are hard to come by.

engine bay looks ready to eat off of! always loved the odd sideways canter the top mount intercooler got on the original WRXs, so odd.

get it, and I will drool, so random internet guy says do eet!

then replace the bumper - http://oppositelock.jalopnik.com/its-alive-5108…

http://oppositelock.jalopnik.com/home-depot-lip…

and buy a can of spray vinyl for the dash parts

http://oppositelock.jalopnik.com/holy-transform…

1337HPMustang > MonkeePuzzle 10/01/2014 at 14:50

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Wow thanks for the great insight! The amount of info opponauts have given me is incredible.

I'm surprised yours was a non interference engine when "gc8foreva" and "boxer_4" mentioned above that the ej20G is an interference engine... Either way, I'll replace the belt on it when I get it so it shouldn't be an issue. And yeah in the last 24 hours I've done nothing but read about 90s wrxs and realized pretty soon it's a "gf8".

Back to your timing belt though; did it melt because it was old and worn or because your engine overheated? Where did the coolant come from?

Third question if you don't mind sharing your expertise; what is a "Rob-tune"? The importers are offering it and I'm wondering if it's something I should get. Thanks again so much for your help.

MonkeePuzzle > 1337HPMustang 10/01/2014 at 15:47

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my timing belt melted because my water pump ceased. everything else continued to spin and it all failed pretty spectacularly. Coolant leaked all over because the water pump ceased and then I had pressure issues and a hose blew off.

you can follow the whole project here. I bought a new engine and did a timing belt water pump etc change on it and dropped it in. then tidied up the old engine and sold it also

http://oppositelock.jalopnik.com/tag/subaru-sum…

the others are right, because its a turbo WRX from the japans yours should be interference even though it is older, my apologies.

rob-tune isn't something I'm familiar with, but looks to be an ECU modification designed for this gen of impreza. sorry I can't advice one way or the other on it

1337HPMustang > MonkeePuzzle 10/01/2014 at 15:57

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Ok thanks for the insight. You rock. I most certainly will be getting this car so soon we'll be imprezzie buddies

Boxer_4 > 1337HPMustang 10/01/2014 at 16:17

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Glad I could be of help! I'd definitely buy that car for 5 grand!

SantaRita > 1337HPMustang 10/01/2014 at 16:38

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FWIW, the Mitsu TD04 in 15 trim will support up to 300hp or so.

1337HPMustang > Boxer_4 10/02/2014 at 23:10

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hey boxer, so that wrx sold today as I was going to put down a deposit. Shucks. The importer tells me however that he just bought a '99 STI gf8 at auction. This one

"122,000 km. It's a 1999/11 manufacture month. It's a version 5 STI! So it has the EJ20K engine that makes V5's so much more desireable and durable. I'll be asking around $6,500 total cleared customs price for it."

I went on the forums and found out that the version 5 and 6 STIs had open deck ej207s... is that accurate? And apparently they can't handle more than 300 hp before they start to eat head gaskets too. Could you help me understand why the STI, which was supposed to have a homologation motor, isn't durable? Am I missing something or did I read some misinformation? What is an EJ20K and an EJ207? I hope you don't mind if I ask you a little bit more about imprezas

1337HPMustang > Boxer_4 10/03/2014 at 00:10

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Boxer_4 > 1337HPMustang 10/03/2014 at 10:51

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Sorry to hear about the WRX.

I'm a little confused about what the importer claims this car is. If it is an 11/1999 manufacture month, then it would be a Version 6 STi, not a Version 5 STi. The change over from Version 5 to Version 6 was in 9/1999. Granted, the Version 5 and Version 6 are the same mechanically, but still...

Also, I'm pretty sure that the Version 4 STi was the last to use the EJ20K. Both the Version 5 and Version 6 STi had the open deck version of the EJ207.

Where did you see that the EJ207 in the Version 5 & 6 STi can't handle over 300 hp before they have head gasket issues? I've been looking online, and can't seem to verify that information.

While the Version 7 and up EJ207 is the engine of choice for those going for big power (450 hp or so and above) due to it having has a semi-closed deck, the Version 5 & 6 EJ207 is no slouch.

I'd see if you could get a picture of the chassis plaque to get a clear idea of what this car actually is. It will have the manufacture month and the engine code on it.