Fifth gen engine rebuild

So the legacy has developed a pretty bad misfire at idle after overheating. I’ve checked the basics like plugs and coils with no luck. I’ve decided I’ll rebuild the engine in the new year. I have never built an engine before but am sure that it’s a project I can handle. The ej has enough of a following that there are videos out there for the assembly process. Where I may run into some issues are the differences that come between the STi and the legacy. I’ve heard there are different compression ratios, pistons, cams, oil pumps, etc. I’m hoping to get the car to a reliable 350 whp daily. I’m not sure if that can be achieved with the stock turbo, and just different internals. I intend on purchasing an invidia n1 and pairing it with the catlesss invidia downpipe I have in the closet. I have a spare vf54 I intend on porting before installing. I’d like to go with the STi exhaust cams, and oil pump. What I’m really unsure of is the matter of what pistons to go with, where to source proper valve buckets and what a machine shop would take care of with regard to the valve stems and buckets. Any and all threads you could point me towards, and personal experience is much appreciated. I know this will be a costly project, but it is definitely something I’ve always wanted to do.

Oem oil pump is an upgrade over every other ej255 and I believe is the STI pump. So get the one for our car. Buckets are available from the dealer or any subaru shop, I personally would get the camshafts and install them before ordering buckets you may not need new ones. What I have read is, once installed you can move buckets around to ensure the clearance is within spec on each valve in most cases. There isn't a variety set of buckets, you would need to order the correct thickness, and the only way to know that is to test fit.

 

If I was you I would talk with an engine builder and get their take on what you want and where you are starting, they do this for living and can help you save money by eliminating unnecessary parts/work.

Thanks. I intend on speaking with the local Subaru tuner (precision tuning) to get their take on this. I would most likely go to them for the tune after the build is done. They do also build engines.

Sorry to hear of your possible bad luck with the car. Although, you made it a lot further than a lot of the 5th gen GT's I have seen around here before a build.

 

I ended up diving all in recently and went with most all the upgrades in my build... New Stage 2 block, HTA71 turbo, flex fuel, upgraded injectors/fuel pump, Invidia down pipe, AWIC, TGV delete, 2011 STI cams, ARP head studs, 1.0mm Tomei head gaskets, South Bend stage 2 daily clutch, Verus billet clutch fork and pivot ball, PDM TSK3 throw out bearing and sleeve, AFR sensor and maybe some other stuff I'm forgetting right now.

There was a bunch of other small things and all the orings and seals eventually ended up coming from Subaru.

 

I got the car back together and the Felpro cam seals were leaking. All 4 were leaking. I put the Subaru ones in and all good.

 

How long/bad did your car overheat?

It’s hard to say how long it lasted for. I was going uphill over a bridge on my way home from work. As i approached the top of the hill i noticed my temp light flashing red. I looked at the accessport and noticed the coolant temp at 248F. I immediately cut the engine off doing 70 mph and coasted to a stop on the shoulder of the bridge. When I got out, I saw the lower coolant hose hanging from the water pump. It could have fallen off and over heated, or over heated and blown off. Hard to tell. That 248 degree reading is also hard to distinguish since the car wasn’t reading coolant temp if there was no coolant. The engine itself could have been much hotter.

 

I notice you didn’t mention pistons or bearings. Did you buy a preassembled block? What block did you go with? If it was an STi, did you run into any issue with compatibility of your parts from your legacy?

I had a local place build it for me. I haven't built one before, I figured they have better options for better fitting bearings and the experience of prior builds. It wasn't cheap, but has been great so far.

 

They started with OEM case halves. The LGT cases have a different bolt pattern for the oil baffle that the oil pan connects to. That's really about all there is different with our blocks compared to the others.

 

Here's my block build sheet, gives the example of a possible price as well... ouch.

 

Oh yeah, I upgraded my valve springs to the Brian Cower spring set, forgot that one on the list previously.

Wow, thanks for that info! That seems like a price I’d have to jump on if it were presented to me. My local Subaru tuner is closed sundays and mondays. I’ll have to stop by there on Wednesday and see what they have to say. Even if I just get an idea of what they’d do could help me decide what route to go.

This weekend was the first weekend of the engine tear down. I’ve got the heads off and pretty much the only assembled component left is the block. I’ve been putting together a cart on subarupartswarehouse.com for anything that must be replaced regardless of the route I go (hoses, clamps, rusted fuel lines etc). It’s getting expensive:spin:. I’m a little unsure of what route to go moving forward. I’ve spoken with head games motorworks who seem to have an incredible reputation. They quoted me 1200 to refresh the heads and add a spring kit prior to me finding a cracked exhaust valve. Subaru sells the heads for $540 a piece, but I’m thinking those don’t come with springs valves etc. I’d like to go with Sti cams as well, if anyone can chime in on the extra work required for machining the intake cam for the oil scavenger pump.. The block looks fine from what I can see, but I’ll likely be going with new piston rings and bearings just for piece of mind. I’ll post some pictures soon.

 

 

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I’d like to go with Sti cams as well, if anyone can chime in on the extra work required for machining the intake cam for the oil scavenger pump.

 

The 08 and up factory STI passenger side cam is already machined for savage pump. The intake STI cam are the same as our, so they aren't needed anyways.

Our engines already have the larger STI oil pump. IIRC you have 200k+ miles, so I would replace the oil pump anyways.

Thanks for that. I remember reading about someone having a cam machined, but it may have been for a different MY of the Sti.

I think S2baru had to do that, but he has non-OEM STI cams.

I think S2baru had to do that, but he has non-OEM STI cams.

 

That’s what it was. Looks like I’ll be going with oem.

I went with used 2011 Sti cams and they fit like a glove...

I went with used 2011 Sti cams and they fit like a glove...

 

Thanks. I’ll be going with oem as well.

Definitely price check against Heuberger Subaru (https://parts.bestbuysubaru.com/Subaru_2010_Legacy-25L-TURBO-6MT-4WD-GT-Premium-Sedan.html) They sell their parts online at 36% off.

 

I had the same issue as you. Burnt exhaust valve on #4.

 

I ended up just buying a brand new replacement shortblock from Heuberger along with a gasket kit, replaced all my turbo oil and coolant lines, turbo oil pan, lower oil pan, oil cooler, oil pump, filtered banjo bolts, O2 sensors, a couple ignition coils along with a lot of other associated gaskets, hoses and stuff. Spent about $3k there, and the another $1k on ARP head studs, head gasket, timing belt kit, spark plugs, belt, break in oil and other stuff I can't think of. Head work was about 800, but they essentially just cleaned and refreshed my heads, replaced 2 valves and replaced the seals.

 

Getting that new shortblock from Subaru has really helped me trust this engine more.

So the legacy has developed a pretty bad misfire at idle after overheating.

 

When I had headgasket failure and overheating, it also lead to a misfire.

 

After I rebuilt the engine and had it back together, the misfire remained. Turns out one of the injectors failed.

 

I believe the failed injector and rich condition also lead to a melted cat.

 

Hopefully you don't have that type of luck.

I would check the exhaust valve clearance on #4, which is the likely cause of the burnt valve. I would guess it is zero. If you don't have feeler gauges when it is shimmed properly you can see light between the camshaft base and lifter bucket. You can also have you injectors sent out to be cleaned and flowed for peace of mind.

Subarupartswarehouse still looks like it’s cheaper than other site, but the websites look identical.

 

The heads are going to headgames on Saturday as long as my cams get here in time. They’ll check the clearances on the valves as part of the refresh.

 

I wasn’t aware I could have the injectors cleaned. I’ll definitely have to look into that.

I just got off the phone with the tuner I plan on going with. I was mentioning the block to him and who I should go to for the work, and was pretty surprised to hear his advice. He told me a brand new short block from Subaru is $1000. He said the cost to have the stock one machined would be close to same price and so just buy a new one. Anyone have any prices from the machine work for their blocks?

A new block (10103AC860) is about 1800 depending on your discount. I went that route since really that sort of quality control is hard to beat. Also the fact that i plan on never really going past stage 2 was in play since this is my dad-car. Any real internal upgrades wont really be used to their potential and be mostly wasted cost