Turbo Failure:  A Warning to '02-'06 Turbo Subaru Owners

"Boxer_4" (Boxer_4) 01/24/2017 at 16:45 • Filed to: None

10

30

Several months ago, a friend of mine bought a mostly stock ‘03 WRX. All was well until a few weeks ago, when he got a check engine light and was noticing a lack of power. Using the ever-useful !!!error: Indecipherable SUB-paragraph formatting!!! with FreeSSM, I was able to pull an Exhaust Gas Temperature Malfunction code (P1312). Us two, and another good friend, were able to correct the check engine light with a 2.2kohm resistor. However, the lack of power still remained. A test-drive while using real-time monitoring with FreeSSM and watching the installed boost gauge showed that no boost was being produced, and the wastegate solenoid was behaving as expected. There were no cracked hoses or exhaust leaks. With these things in mind, there were a few possibilities for the cause of the issue. However, I had a gut feeling what the problem was...

In the US market, the 2002-2005 WRX, 2004-2005 Forester XT, 2004-2006 Baja Turbo, and 2005-2006 Legacy GT and Outback XT had a pre-catalytic converter in the joint-pipe (commonly known as the uppipe). The joint-pipe is the pipe that connects the header to the exhaust inlet of the turbocharger. Also included is an Exhaust Gas Temperature (EGT) sensor, intended to monitor the temperature (and in theory, the health) of the pre-catalytic converter. In some cases, the pre-catalytic converter can break apart and get sucked into the turbocharger (also taking out the EGT sensor in the process).

As you can probably imagine, that’s not a good thing...

The WRX owning friend came prepared with a new TD04, expecting to replace a seized turbo last Friday evening. Myself and the two other people who were now helping him on the job were hoping it was just going to be a simple turbo swap. Wishful thinking on our part... the turbocharger was completely seized, with chunks of pre-catalytic converter falling out of the turbine wheel housing... we knew we had some work ahead of us...

It was at this point that we know both the joint-pipe and center-pipe (dump pipe) needed to come out. As the dump pipe was pretty much permanently attached to the rest of the rear section of the exhaust due to 14 years of PA winters, we were pretty much forced to remove the entire rear section of the exhaust in one piece. That was fun without a lift... The picture above shows what came out of the dump pipe.

Removing the joint-pipe involved fighting rusted bolts with penetrating oil, a blow-torch, and eventually, a grinder. When we finally got the joint-pipe off, we saw that what remained of the pre-catalytic converter was loose inside the pipe. Even before we discovered that, we knew the pre-catalytic converter needed to be removed from the system to prevent damaging the new turbo. Going for the cheap option, we decided to gut the original joint-pipe. This was the result:

Gutting the joint-pipe was a lot more difficult than we anticipated. What remained of the pre-catalytic converter was quite robust, requiring the use of a hammer and chisel, and eventually, a hole-saw.

Reassembly went better than disassembly, however, it still wasn’t completely smooth. After fighting with the joint-pipe for what seemed like forever, we finally got the exhaust reinstalled. By comparison, installing the new turbo was fairly easy.

By the time we had everything put back together, the turbo primed, and the coolant level topped off, it was past 3am on the second evening we worked on the project. We all went for a test drive, and other than all of the smoke and steam from all of the penetrating oil used and coolant spilled, it ran perfectly.

In the end, the project was a great success, and us inexperienced mechanics got some valuable wrenching experience. However, I have a newfound hatred for pre-catalytic converters...

Roadster Man > Boxer_4 01/24/2017 at 16:52

1

Tru Dat. Removing the “up-pipe” with the cat is a must-do for these Subarus. Otherwise you basically have a ticking time bomb, with the catalytic converter just waiting for exhaust gas to blow a piece of it into that delicate little turbine...

Subaru has made some questionable engineering decisions with these cars... a pre-turbo cat and valve covers that sit directly over the headers, so that when a valve cover leaks the car smokes like it’s about to explode.

RiceRocketeer Extraordinaire > Roadster Man 01/24/2017 at 16:59

2

Seems like a common issue among cars at the time - were automakers just starting to figure out cold start emissions? I think the Sentra SE-R Spec-V and Mazda6 V6 of that time had similar issues with the pre-cats disintegrating and causing havoc upstream.

DC3 LS, will be perpetually replacing cars until the end of time > Roadster Man 01/24/2017 at 17:09

0

Overall how are Subaru’s to work on? I’ve worked quite a bit on 4 cyl Japanese cars, but never a Subaru. The boxer engine just seems like it would be a PITA compared to an inline 4. Is there any truth to that?

Master Cylinder > DC3 LS, will be perpetually replacing cars until the end of time 01/24/2017 at 17:20

2

My LGT is pretty OK to work on. The boxer layout has some advantages (i.e., allows the use of a top-mount intercooler so the turbo and plumbing is actually fairly accessible.

Anything that has to do with the heads is obviously more of a hassle, of course. Spark plugs aren’t much fun (which is why manySubaru owners tend to opt for iridium plugs to avoid having to do it more than once eveyr few years) and head gaskets are an engine-out deal.

Overall, though, they’re not really any different than other cars to work on.

Master Cylinder > Roadster Man 01/24/2017 at 17:21

1

I still have to do this on my ‘05 LGT. Mostly I’m trying to resist the urge to also add headers to my order....

TheTurbochargedSquirrel > DC3 LS, will be perpetually replacing cars until the end of time 01/24/2017 at 17:22

3

They are generally OK until you have to do something on what is traditionally the top of the engine. Spark plugs, valve covers, etc are all more difficult to get to than they are in a more traditional layout. Other than that they are actually rather simple and easy to work on. Subaru hasn’t fallen into the trap of packaging everything into a tiny space like a lot of companies have (they also don’t try to hide everything under massive lumps of plastic).

BeaterGT > Boxer_4 01/24/2017 at 17:22

1

Yeaaaahhh, I still need to do this. I just brought my car back from the dealer with more problems than I brought it in with (0)!

CobraJoe > Boxer_4 01/24/2017 at 17:24

1

And that’s why I’m planning on replacing my stock uppipe with a used COBB uppipe tonight on my ‘05 Legacy GT.  

Took the oppurtunity to wrap the new uppipe with some heat wrap and I’m planning on doing the same with the downpipe to make sure I keep all the heat contained as much as possible.

CobraJoe > Master Cylinder 01/24/2017 at 17:26

1

I resisted that urge by having a separate project car and by buying an aftermarket uppipe second hand.

Got a nice COBB pipe for $50. Can’t argue with the slightly discolored looks of it for that price.

dropthatclutch > Boxer_4 01/24/2017 at 17:46

1

This happened to me. Used it as an opportunity to remove all the cats and upgrade the turbo to a TD05/18g hybrid. Though I paid a shop to do the work.

Roadster Man > RiceRocketeer Extraordinaire 01/24/2017 at 18:29

0

Really? I didn’t know that other automakers made the same mistake, I thought it was only Subaru was silly enough to think it was a good idea.

Learn something every day!

Roadster Man > DC3 LS, will be perpetually replacing cars until the end of time 01/24/2017 at 18:34

1

The only thing I have as a comparison is my NA Miata, which is super easy to work on. Like someone else said, everything is pretty much the same except the head. Spark plugs and valve cover gaskets are a pain compared to just popping the hood in an inline 4.

Boxer_4 > RiceRocketeer Extraordinaire 01/24/2017 at 21:37

1

I knew about the issue with the QR25DE in the Sentra and Altima, but I wouldn’t be surprised about other cases existing.

Subaru switched to secondary air injection on turbo motors for the 2006 and 2007 model year depending on the model. Even this system isn’t without issues (valves sticking and pump failure not uncommon plus a recall for a faulty relay), but at least a failure doesn’t take out the turbo, or worse.   

Boxer_4 > CobraJoe 01/24/2017 at 21:41

0

Good call in getting an actual catless uppipe. It is well worth $50 to not have to gut the OEM uppipe. That was a pain, and took much longer than we expected.

Boxer_4 > BeaterGT 01/24/2017 at 21:56

0

From CobraJoe, it sounds like a catless uppipe can be had for pretty cheap. Removing the uppipe isn’t too terrible as long as your bolts aren’t too rusted and you remove it from the top after removing the turbo. Reinstalling it took more effort, however.

BeaterGT > Boxer_4 01/25/2017 at 00:29

1

I’m not that confident in my own skills to do this job, I might bring it to a shop especially because  the bolts everything will be rusted to hell. Thanks for the reminder !

BeaterGT > CobraJoe 01/25/2017 at 00:30

0

How was the job?

CobraJoe > BeaterGT 01/25/2017 at 09:34

0

Not bad, but there are a lot of parts to remove, so it took a lot longer than I planned on (started at 830pm, done at 1am). Intercooler, down pipe, crossover, passenger side manifold all have to be removed to get the uppipe out, and even then it was a lot of wiggling and pulling to get the old pipe out (I finally bent the EGT sensor tail to get it out). I also reused all my old gaskets, but with a thin bead of Ultra Copper on them to make sure they seal.

Sadly, I couldn’t get a sample of any power gain, we had some snow last night and a lot more coming this morning. It seems a little quicker to get on boost, but hard to tell when it’s this slippery out.

BeaterGT > CobraJoe 01/25/2017 at 09:41

0

Oh man, definitely doubting my technical ability on this one. I’ll have to keep my eyes peeled for a catless UP.

CobraJoe > BeaterGT 01/25/2017 at 10:11

0

I’d say it’s possible for someone who knows basic wrenching with one provision: that none of the bolts are too rusty. My turbo was replaced before I got the car, so every bolt and nut came out easy. I’d bet that the front crossover pipe would be the most likely to be rusted, high heat and close to road salts, so if that won’t come out, you might as well leave it to a pro to avoid the frustrations of fighting rusty nuts elsewhere.

If it’s not rusty, everything else is pretty straight forward, even though there are a lot of pieces coming out, I’m sure there’s a youtube vid on how to do it. I’d highly recommend planning on a whole saturday to work on it though, and a buddy to help you to at least provide a ride to the parts store if needed, but I’d say it’s a decent job for someone wanting to learn to wrench more.

BeaterGT > CobraJoe 01/25/2017 at 10:18

0

That’s the thing, I’m in NJ so I’m sure it is incredibly rusty. Snapped a bolt doing the wheel bearing last time around.

CobraJoe > Boxer_4 01/25/2017 at 10:22

0

Considering this is my daily driver and I’m currently without a running project, I really didn’t want to chance taking off a stock part and ruining it without something ready to replace it, plus I’ve read about how hard it is to actually gut a cat, not something I’d want to do in a time crunch.

Though I did underestimate the time it would take to remove the old one and stick in a new pipe, I got out of the garage at 1am.

CobraJoe > BeaterGT 01/25/2017 at 10:26

1

I snapped a brake caliper bolt not too long ago, but the exhaust bolts were all nice and clean. There’s an easy way to check: Pull off one of the manifold heat shields next time you’re under the car, should on take 5 minutes and you’ll get a good look at the crossover bolts.

But don’t let me talk you into something you’re uncomfortable doing, I just like to see other people wrenching on their cars.

BeaterGT > CobraJoe 01/25/2017 at 10:31

0

I hear ya, and appreciate it. I enjoy wrenching on my car as time goes on but it’s not exactly fun working on a cold driveway either! Brake caliper bolt is exactly what I snapped.

BeaterGT > dropthatclutch 01/25/2017 at 10:38

0

How was that turbo upgrade? Did you need any other supporting parts?

uofime-2 > Boxer_4 01/25/2017 at 12:39

0

I’d have been worried about crap falling down into the header then getting blown up into the “new” turbo once the engine can breathe again.

Boxer_4 > uofime-2 01/25/2017 at 13:48

0

Believe it or not, the precat was only breaking apart from the end closest to the turbo exhaust inlet. We had the exhaust off up to and including the right-side exhaust manifold, which came out clean. We left the front-pipe and left exhaust manifold installed, but did take a quick look into the front-pipe and it looked clean. It would be a good idea to remove the remaining parts when doing this job, but it depends on how broken apart the precat is. Honestly, he was quite lucky how it failed.

Boxer_4 > CobraJoe 01/25/2017 at 13:54

0

I was surprised how solid the precat actually was. I would have thought it would have been fairly fragile, but even with it broken free of the uppipe already, it still took a good hour and a half of working at it and trying various things.

An aftermarket uppipe like a COBB should flow better anyway; even without the precat the stock uppipe is fairly restrictive.

I, too, was surprised by how difficult the uppipe removal and install was. The bolts for the heat shield and the pipe itself were very rusted (a downside of living in PA), and it took quite a bit of maneuvering to get the pipe reinstalled.

CobraJoe > Boxer_4 01/25/2017 at 14:29

1

I know I was lucky to avoid rusty bolts, perhaps because the turbo was replaced by the previous owner, and I ended up bending the tail on the EGT sensor to get the old pipe out and the new one in.

I’m sure I gained a bit of power, but sadly its snowing today so I don’t have a good comparison yet.

Thanks for validating my thoughts of not gutting the stock pipe, I was seriously considering it to keep the costs down to spend more money on the project car. (That strategy isn’t going very well though).

dropthatclutch > BeaterGT 01/25/2017 at 16:19

0

Bigger fuel pump, bigger injectors, bigger intercooler (w/ upgraded Y-pipe), stiffer turbo inlet, catless up-pipe, catless down-pipe, and boost controller. That’s on top of a cat-back exhaust and intake I already had.

Wasn’t cheap but once the turbo had to be replaced it was the way to go.