My EZ30 Tear-Down Thread

[keltik]

So out of curiosity im ripping apart my EZ30 to find out specifically what broke. Will post the thread on many forums so the internet can have more pictures and information on EZ30 internals because hell - there just isnt much out there at the moment. Im going to take a lot of pics and present things as i see them. Im not an engine builder by any means but will offer some worthless opinions. My hope is that these pics can be used by future people that want to do some work on their H6's.

Back Story:
Had this;

In this;

And produced this many torques;

Lowest plot is at 170,000km with factory ECU, top plot is the same day with the Link G4, middle plot is at 120,000km all stock standard.

It eventually started chewing through oil and quickly started smoking up a storm so has been replaced with this;


Ripping into the old motor: Day 1
Popped the valve covers and front timing chain cover off. Everything so far has been spotlessly clean. This engine did 200,000kms under my right foot - those of you who know me will know that im not afraid to give my car an utter raping on the right occasion. BUT, and thats a big but, I do look after it. I run a good quality oil, use genuine Subaru filters and have always run the factory airbox with a genuine cotton filter in it. Genuine filters do seem to be of a much higher quality than the aftermarket ones available in my area.

Heres the inside of the cam covers and timing chain cover;


Inside the left hand bank;


Inside the right hand bank;


Inside the timing chain casing;




Tomorrow I'll be popping the heads off and chain tensioners guides off to look for wear. Comments are welcome. If there is anything you want specifically measured or inspected - let me know.

[chuckthefuk]

+1

[Dead91silvia]

Good God! Thats a lot of chain!

Just wondering, does it ever call for service on anything behind the timing cover?

The heads look like EJ25 heads with an extra plug... haha

[keltik]

Day 2: LH Bank + Head Off
Ok so today i got the left hand head off and cams out to inspect the journals. I also inspected the timing gear since ive always wondered how much it wears over the engines life. Without further ado, more pictures!

Timing Gear
First up - The EZ motors do not use a hydraulic tensioner like the EJ, they appear to use a spring loaded tensioner which is fed oil pressure to tension the chain when running. Its a very simple but great design using a screw shaped insert to stop the tensioner retracting when the engine is stopped.


The water pump was tight and smooth, as good as a brand new one i'd say. There was evidence of a little bit of dried coolant through the weep hole but the bearings felt very good. The pump is sealed by one O-ring which was also in good condition.


The timing chain itself was in good condition, i didnt measure it for stretch but in place it was still taught with little slop. All of the guides and tensioner runners were extremely clean with very little signs of wear. I was expecting it to look a LOT worse than this but theres only a couple of small wear patches on the tensioner runners. All other guides are good.


I also checked the bearings in the chain idlers and they both appeared quiet and smooth. The transfer idler that runs the RH bank was a little looser than the rest and i would probably have replaced it were i rebuilding. They arent that expensive out of the states.


RH Head
The head itself was clean but combustion chambers were carbon'd up pretty badly. The first thing was to check the cam journals and they all appeared clean with no burns or scoring. Some light scuffs on the intake journals and exhaust were all clean.




The head gasket was clean and showed no signs of leakage. This is where the problems started showing up. As i whipped the head off - all the bores had about 4-5ml of oil in them. The bores were very clean with cross hatching still visible and no scoring - but they were full of oil...all of them. Heres the crowns of 2, 4 and 6 in that order. 2 was very down on compression.




I discovered you need to remove the timing chain rear cover to remove the LH head, didnt have the tool so will continue with that tomorrow. Then hopefully day 3 will be the bottom end inspected and we should know once and for all what killed this motor.

[1996Battlewagon]

IN! You sir are a trailblazer.

It looks like you had really bad blow-by but everything else, especially the timing system, looks great. Those chains are just cool and make so much sense.

[keltik]

Day 3: RH Bank and Head Off

So today i whipped off the front timing cover, removed the head and took a look at the state of things on the RH bank.

First up was to finish removing the rear timing chain cover, to get it off you need to remove pretty much everything from the front of the motor. So off came the oil pump pressure relief block, chain idlers and a whole mess of bolts. Interesting point - the idler bearings are pressure lubed and fed oil from the rear - which explains the lack of wear on them and lack of a service interval.

With all the crap removed - the front of the motor looks something like this;


Then it was on to removing the RH head. Cams out first revealed yet another spotlessly clean cam case and another set of spotless bearings;



The chambers on the head were again rather carboned up but differently to the LH head. The tops of the chambers were spotless and the bottom 2/3rds were oily with one cylinder being heavily fouled;



Here we see the crowns of cylinders 1, 3 and 5 in that order;




The buildup of oil sludge leads me to believe that this bank had only recently started to burn oil compared to the LH bank which had a much more consistent coating of carbon and thicker deposits on the piston crowns.

The bores were again score free and clean, no signs of scuffing and cross hatching was still visible;


Everything so far is pointing me towards oil control ring failure since all cylinders had oil in them when the heads were removed. This would also be consistent with the heavy smoke at startup reducing as the engine warmed up. I was kinda hoping for some catastrophic failure carnage, but this looks more like wear to me. The only question it raises is whether or not the sudden onset of smoke was caused by a drop in oil pressure or just wear and tear taking its toll.

Tomorrow I plan on splitting the block and taking a closer look at the pistons and rings. Will also have a look inside the oil pump.

[Huffer]

I'm stickying this thread because there's so little info about this engine, and it looks like keltik is going to provide us with a LOT.

[02_Legacy]

I don't know how you would test it but could the problem have been valve stem seals? If the stem seals go bad oil can leak down the valves and into the combustion chamber. Also with bad valve stem seals it would smoke worse in high vacuum conditions such as idle and decell, and smoking would decrease closer to WOT. I'm also thinking that it could be worse right at start up as oil settles and puddles in the head.
Could be wrong but i'm just throwing it out there.

[keltik]

Stem seals was a possibility, but the ports are clean and i would expect to see oil residue in them if the stems had been leaking. Also i was getting a fair bit of blow-by so yeah, rings seems to be the more likely culprit.

[keltik]

Day 4: Block split and bearing inspection
Alright so I finally got round to splitting the block and having a look at the bottom end. First to remove was the steel sump pan, then the alloy upper sump.
Upon removing the steel pan, i noticed what appeared to be a spongy donut underneath the oil pickup;


But after giving it a rub, i noticed it was actually a magnet designed to catch the fine metal particles before the mesh over the end of the oil pump pickup;


It concerned me slightly since the oil pump pickup had very little clearance between this donut and the strainer to suck oil through. I dont think it was significantly harming flow, but it might be something to keep in mind once your motor is getting up in the k's.

Here is the upper sump section which houses the waterpump and a few other things;


And here is the block with the sump completely removed;


Next the gudgeon pins needed to be removed. To do this, access panels on the front and rear of each head are removed - then you use a very long pair of needle nose pliers to undo each of the circlips on the outside of pistons 1, 2, 5 and 6. Then once those pistons are removed - you can reach through the outside bores to remove the pins from pistons 3 and 4. Its quite a fiddly job and if i were to do it again - i would probably get the subaru factory tools for doing it.

With the pistons removed, the block was split and all bearings were laid out and examined. Here are the main bearings and the crank. All surfaces were very clean with only a little scuffing on the center mains. The rear thrust surfaces were the most worn but still well within wear limits;


Heres the big end bearings. Again, all were clean and free of significant marks. All were probably on the limits of wear tho as i did notice a little bit of slop in them. I dont know what the appropriate clearance is, but these felt a little on the looser side of acceptable;


Heres the conrods and pistons. All conrods looks straight to my eye, no signs of damage. I did hydraulic the motor once using upper cylinder cleaner - but that clearly did no damage. All piston skirts had a little scuffing, nothing serious. All rings were in tact including oil control rings. All surfaces and edges were clean and sharp with no cracking or any signs of anything amiss;


More detailed inspection of the cylinders revealed them all to be in good condition. They were very smoothly polished. More than i wouldve expected. There were no scuffs or scores to be seen or felt;



Conclusions: What i learned here today

So there wasnt a smoking gun as such. No one component showed obvious signs of damage. I didnt do much measuring with the micrometer so that probably could have told me more about what was going on, but frankly, i just didnt care enough to bother.

The EZ30 appears to be very well engineered and laid out. Even more so than the EJ20. Every component felt of very high quality and the machining of the block and heads appeared to be very good with little casting marks or rough surfaces. The inside of the motor was remarkably clean and smelled of lightly used oil. It was nothing like the coked up carboned sludge filled lumps of shit ive disassembled before.

Due to the lack of any obvious failures, im putting my oil burning down to glazed bores or excessively worn rings. I dont know what would have caused the sudden onset of either scenario but will do some reading and see what makes sense.

[Huffer]

Amazing engine. Thank you so much for the valuable pictures and notes!

[Benfolio]

Out of curiosity, did you do a leakdown test of the heads? Turning them upside down and filling the combustion chambers with gas and seeing which one, if any leaks out gas will point you to of the problem WAS in the valve seals.
Buddy of mine has a built STi and is dealing with the same problem, burning oil but with no clear reason why. I know the turbo ads a bit of complexity to the equation, but based off what he found so far tearing his motor down, and what little I know, I am suspecting rings or valves.
Just curious to see yours as well.

[Patrick Olsen]

Just out of curiosity, were you running conventional or synthetic oil? I don't think that has anything to do with the failure, I'm just curious. I've only disassembled a few engines, but in my experience, synthetic oil tends to not leave that sort of orange-ish staining on the internals.

Thanks for sharing the pics of the tear-down, very cool stuff. I haven't split the block of mine, but I've pulled the timing chain stuff, cams and heads off my EZ30R. There are a bunch of pictures in this folder.

[vristang]

Obviously your pistons were fly-cut from the factory...
My EZ30 does not have fly-cut pistons...

[keltik]

Ah very interesting. I dont check here often so apologies for the late reply.

No i never used synthetic oil. Just a good grade semi-syn. Most of the time it was Castrol Magnatec 10W40. I had also used Valvoline XLD Engine Armor for a wee while.

As for the piston differences - i can only speculate but its possible the differences are because yours is a US or Lancaster spec engine and mine was the Japan only GT30 which also runs a different ECU to the others ive seen.
The service manual doesnt state any differences in compression ratios but its possible i guess.

[Tradewind]

Extremely well engineered engine

You sure there wasnt something wrong with your crankcase breather system?? This situation as shown isnt really showing up as anything of mechanical substance

[keltik]

Nah i ran it with the breather system connected to a catch tank and it came back clean. The oil was definitely bypassing the rings to get burned. The total lack of oil in the intake manifold and ports would confirm this.

Heavy smoke at cold idle, reducing to a light haze when hot is also textbook ring failure. Combined with low compression readings - im 100% confident that rings were the problem.

One thing i hadnt touched on is the fact that my new engine also had an oil usage issue. I switched grades which helped slightly and then ran a couple of cans of cylinder cleaner through it.
It was still smoking a bit so i took it on a track day and gave it death. The theory was that the rings/bores had glazed from being idled around town all its life.
I figured if it explodes - i lost an oil burning piece of junk. If it lives, i might just fix it. After that day, oil usage dropped a lot and 6 months later its at a level im happy with.
Approx one quart every 6,000 miles with no visible smoke unless doing high rpm engine braking.

After talking with the biggest Subaru dismantler in the country and a couple of highly ranked service technicians from Subaru, it seems oil usage on these motors is a fairly common
issue. Internet research seems to back this up. I have no opinions on the correct way to fix it - just reporting what i found with the wear on my old engine and the improvement
on my new one.

[keltik]

Also, to add one more line of wisdom to this thread;
My old engine did 200,000km with me and was used brutally at times. It performed well, was efficient, quiet and smooth for all its life.

My new engine (EZ30R with VVT) is more powerfull, records a better highway mpg and has better torque througout the rev range.
It is by far a superior engine to the old EZ30. The power difference is astonishing! I run an aftermarket stand-alone ECU and the new engine
is much more tunable and responsive than the old. Anyone looking to put an EZ30 into anything should only consider the newer motor. The old one by
comparison is a turd.

[Patrick Olsen]

How did you actually pull the piston pins? I have one of the turd motors in my garage and I'm in the process of tearing it down to clean it up. I got it dirt cheap, and the guy that I got it from said it had "a noise", hence the tear-down. A couple nights ago I bought some long needle-nose pliers so I could reach in and get the circlips out, but I don't have a way to get the pins out. I've seen various tools that folks have made over on NASIOC, just figured I would ask you since you've torn down this type of engine yourself.

This engine is definitely not clean and purty like yours, or like the completely spotless EZ30R that I also have sitting in the garage.





Compared to the R motor:

[keltik]

I actually used a long length of threaded rod with a washer between 2 nuts on one end. I then threaded it through the center of the pin and hooked it onto the pin i was working on, then used a claw hammer on the rod to pull it out. Sounds messy but worked a treat.

[Patrick Olsen]

I ended up making a tool with some 1/4" steel rod.



I also figured out it's easier to knock them out from behind rather than pull them out.