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EJ25D at Home Rebuild

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Not a Subaru engine that is worth rebuilding to make any kind of real power (nor is it known for reliability) but I am very low on funds and needed to get my car on the road for winter. I suppose I should give some background information to start out. About 6 years ago I was t-boned in my 98 black sedan LGT and sadly it was deemed totaled. Because I was at fault and did not have collision I was left with this functional but wrecked car. I bought a 98 LGT wagon with a blown auto transmission for $400 and proceeded to swap the drivetrain from my totaled sedan into the wagon. I kept the engine out of the $400 wagon and scrapped the rest of its drivetrain along with the shell of the sedan. Keep in mind that when I bought the sedan it had over 180,000 miles on it. Around 4 and a half years later of driving the wagon and the engine began to misfire when it was cold, plus it had low compression in cylinder #1. It was then that I decided it would be a good idea to swap the engine that I kept, back into my wagon. Long story short I should have tossed that engine the moment I saw inside because it was never well maintained and ultimately that engine spun a rod bearing and my car sat in my driveway for around a year.



All the Rod Bearings (one has a horizontal cut from a hacksaw) ~ These looked nothing like the rod bearings in the engine I rebuilt and unfortunately I don’t have a picture of them to compare


I spent my last year of college driving my brother's 02 civic and I bought a 94 miata in January which I started driving in July after I moved back from college. When I got home I started to rebuild the engine with the misfire and low compression.



Top of the engine I rebuilt before I tore it down, over 200,000 miles worth of crap



Inside the case of the engine I rebuilt before I tore it down



Dirty exhaust valve from cylinder number one, I think this may have been part of the misfire/ compression issue



Windage Tray, Oil Pickup Tube and Oil pump before being cleaned


After fully stripping the heads and the block halves, I soaked all of the internals and the block/heads in LA’s Totally Awesome Cleaner, then power washed them and dried them. It did little for the corrosion that built up on the outside of the block and heads but it did clean all of the oil staining on the inside of the engine. Additionally some of the engine bits needed some TLC to get them clean like the pistons, crankshaft, connecting rods and the valvetrain. The only real damaging build up of oil gunk was in the oil relief holes in the pistons. Besides that and the valves, most of the inside of the engine was just badly stained.



Side by side comparison of the inside of the blocks



Side by side comparison of inside the heads



Both block halves and heads after all being soaked, power washed and dried



All of the hardware for the blocks and heads besides the block bolts and head bolts



The valve train after being cleaned



Side by side comparison of the connecting rods before and after being cleaned



The crankshaft after being cleaned


I was planning on spending as little as possible to rebuild this engine, luckily I had some gaskets to use from an old project on the engine that spun a bearing. I did not take it to a machine shop and I made sure I put everything back together exactly how I took it apart. The only things I replaced were all the associated gaskets, seals, piston rings, a few valve shims, the valve keepers (because I had them) and the cir clips for the pistons.


Since I had time on my hands I decided to balance the pistons and the connecting rods along with smoothing out sharp edges in the intake runners in the heads. To take material off of the connecting rods I purchased a belt sander that I clamped upside down to a bench since it was much more cost effective than buying a tabletop belt sander. Balancing the pistons was easy, balancing the connecting rods proved to be much trickier. After weighing the wrist pins, piston rings and the rod bearings I was ready to start weighing the connecting rods. I spent a lot of time taking measurements of both sides of the connecting rods. The most crucial aspect of producing consistent values was eliminating all movement in the jig. Once I had measurements that I was confident in, I started the balancing process.


First I balanced the pin end, starting by taking the mass of each pin end again and the total mass of each connecting rod. To determine how much mass I had taken out of each rod at any given time I simply took the difference of the rods total mass before I started removing material compared to its total mass at that given point. This gave me a value to aim at when weighing the pin ends after shaving them down. Once all of the pin ends were the same (within .1 grams of each other), I then knew that any difference in the mass between the connecting rods was in the bottom ends of the connecting rods. At that point I was able to weigh the whole connecting rod and balance them by removing material from the bottom ends. I did this while simultaneously double checking the bottom end weight by using my jig.



The jig I made and used to balance my connecting rods



All the connecting rods after being cleaned and balanced



Side by side comparison of a piston that needed to lose weight and the lightest piston



Removing sharp edges from the intake runners


Luckily I was able to correct almost all of the valve clearances by swapping around the shims in the engine and using shims from the engine with a spun bearing. A few shims had to be purchased.



Excel sheet used to determine where each shim should go along with which shims needed to be bought



Lapping the Valves



Checking the ring gaps

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I used 220 for material removal, 320 for a finishing grit and a lot of wd40. A proper straight edge and feeler gauge was used to check for flatness. I'm not sure how much the lapping plate cost my brother but it has certainly saved us money by now.



Flattening a head on the lapping plate



Flattening a block half on the lapping plate



The heads after being flattened



The driver side block half after being flattened



Before honing the cylinder



After honing the cylinder


Once the block and heads were ready for assembly I did another deep clean through all of the oil passageways using a variety of pipe cleaners. I then used a pressure washer again and sprayed it all down and then dried it all off with a compressor. For all of the oil passageways/coolant plugs I used red loctite and I only used Fuji bond on the plugs that called for it in the manual. At first I was installing the valve springs using a C-clamp and a socket with a chunk cut out but then I switched to using a socket with a barrier between the keepers and the socket which worked much better.

Like in this video->

This was the same style tool and method I used to take it apart but this video showed me how to put it back together. I used Por-15 to paint the oil pan.



Installing the valve springs with a c-clamp and a socket before finding that video



Crankshaft and connecting rods assembled and ready to be installed



Bearings installed in the passenger side block half along with fuji bond



Crankshaft installed in the passenger side of the block



The driver side of the block installed over the crankshaft on the passenger side block half



Installing the pistons



Clean windage tray and pickup tube installed



Oil pump installed, oil pan installed, head gasket in place ready for the assembled head



The assembled long block


I broke the piston rings in over the course of 500 or so miles, just by varying the revs and staying below 4500 rpm / half throttle but I made sure I did not baby it. I used cheap oil to start it and let it warm up for the first time and then switched to what I normally use for the first 500 miles and then changed the oil again. I have done full throttle pulls to red line post break in because that is exactly how the other engine spun a bearing...on the first pull. I know the 833 miles I have put on it as of right now are nothing compared to the mileage I’d like to see come out of it but it has been working as well as I could have hoped for so far. This engine is as old as me and had over 200,000 miles on it when I started the rebuild so I am curious to see how long it will last. This rebuild cost me around $550 for parts I needed and consumables. The parts I already had were the new keepers, new O rings for between the block halves, new valve seals, new block bolt o-rings with the orange seal, and a new knock sensor. From the wrecked engine I used the head bolts (because they were essentially new) along with different plugs and bolts. I hope this post helps anyone doing something similar in the future, feel free to pick my brain, criticize or leave additional advice. How many miles do you think I’ll get out of it?

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  • 3 weeks later...

Great low budget garage build. I recently picked up a 02 Legacy Wagon with about 230,000 miles on it. The kid before me pulled the engines and had the heads gone through and put it back together, I wish he had done as much as you did with your engine.


I bet you get at least a couple years out of it, 20-30 thousand miles? Maybe longer, who knows. My only concern honestly is that you reused the head bolts, it is my understanding that these use 'TTY' or Torque To Yield head bolts. What this means is they are designed to stretch into elasticity to allow the bolt to stretch with the expansion and contraction of the heads during continued heating and cooling cycles. Due to this they are a one use only bolt, once they have been stretched, that's it, they are done.


But if you torqued them down via the proper spec and sequence and none of them felt like they went mushy on you then chances are they will go just fine. But there is also a good chance they will just stretch out and not return and you will end up with blown head gaskets, but hey ballin on a budget.


I appreciate your thread, as someone new to these engines it is great to be able to see all the parts in detail in both tear down and reassembly. Good Luck and I hope your engine last you for another 10 years! ;)

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I had very similar concerns when replacing the head gaskets on my engine that blew which is why I bought a set of new head bolts for that engine (costing $90 at the time). Sadly I only got 1500 miles out of them in that engine. I actually recovered the head bolts, which I reused, from the blown engine while it was still in my car. The FSM mentions nothing about needing to replace the head bolts (at least for this engine) and I have seen different opinions about the matter which has brought me to my own ‘conclusions’. First the fact that these are steel bolts that are threaded into aluminum threads. (I do have the old block and might take the angle grinder to it just to see if there are steel inserts) If the threads in the block are just aluminum then I don’t see how those threads wouldn’t be the ones to stretch to a point where they yield instead of the bolts themselves.


Unless you are saying that when you torque down the bolts they are then elastically stretched, which would mean that when you remove them , they should return back to their original un-stretched state (atleast before you start using the engine). Basically, I don’t buy that just the act of installing these bolts is enough to make them one time use, torquing something to be in an elastic state is very different from torquing something to its yield point.


However I can fully envision the bolts being stretched due to fatigue experienced from the engine just running over time along with the heat cycles the engine goes through, especially if the bolts are in an elastically stretched state. These two factors could lead to the head bolts stretching similarly to how valves stretch, over time, and I hope 1500 miles of light driving was not enough to do this. Although I could be wrong about all this and only time will tell! If something was to fail prematurely on this engine I think it would be the head gaskets. I am currently at 1756 miles on the engine I rebuilt and it has been working great so far. I am glad I have a working Subaru again since a foot of snow was just dumped! Thanks for the feedback, indeed ballin on a budget! I would like to put an EJ205 in my car (when I have the money) but I also want to see how long this engine will go for.

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  • 7 months later...
  • 3 months later...

Its been a little over 12,000 miles since I rebuilt the engine and it is running exactly how it was freshly rebuilt. It feels loose before its warmed up and always likes to run at a little higher revs than before the rebuild. In retrospect balancing the connecting rods and pistons may have been not the best idea since I did not replace any of the rod or main bearings. I intend to find out how long this engine will run until it cannot.



The only place I really found gunk in my engine was in the piston oiling holes, which makes sense. The blockage was starting to cause wear on the piston and cylinder walls which would have led to more oil consumption. I wish looked for a correlation between the gunk location and the piston orientation, maybe the fact that these engines are horizontal has something to do with it.



Ideally, I think, anyone who is rebuilding their heads should remove, clean and maybe re-ring their pistons, without splitting the block. You definitely couldn't hone the cylinders but I think that just cleaning the pistons would give every Subaru engine a lot of extra miles. Maybe you could use a thin angled bar and lever against the access holes to poke the pistons out. Or you could probably poke them out from the bottom if you remove the oil pan, pickup tube and windage tray. Whatever the method, it should be standard.

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