EJ25 JDM that I've put 25,000 miles on (and took it apart!)

[Sodo]

Not just for fun!
The timing belt jumped a few teeth and bent some valves.
See other thread: EJ25 timing belt skipped a (few) teeth. See this PSA (video)

Four intake valves were bent. Here's one.
The other intake valve was not being used because this engine uses only 3 valves for low RPM.
At some higher RPM little hydraulic cylinders push a latch and engage a tappet, and the 4th valve opens.

I took the heads off.
Then was persuaded to take the pistons out, hone & re-ring.
I promise I'm going to stop there and put it back together.
Wish me luck.

The bores look good (to me) with hone marks remaining, all the way around and zero detectable ridge at the top.

Here's where I'm at this evening.

My worst piston. All others are less worn.
You can still see the original machining marks.
To me, this is 'good".
Curious what a real mechanic says.

Also I expected the oil rings to be "coked up".
They look clean to me.
But they look much less "energetic" than the compression rings.
Again, what does a Subaru mechanic say?

I will put them in the bores and measure the gap.
Does anyone know the EJ25 2010 ring gaps?
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'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[Vanagon Nut]

I don't really "know" what I'm looking at but....

Any idea how many miles on engine before you got it?

Neil.
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1981 Westy DIY 15º ABA

1988 West DIY 50º ABA

VE7TBN

[Abscate]

Casey sez “ you can put a WBX in there as an interim solution for the next 100k miles while you repair that”



Sounds you like you need Bentley for the Roo for those specs

https://www.youtube.com/watch?v=p8JjvCHvAIo
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.ssS!

[Vanagon Nut]

As a guess, as shown in the image, skirts et al of 2 pistons at LH of image look more worn than pistons at RH side.

Neil.
_________________
1981 Westy DIY 15º ABA

1988 West DIY 50º ABA

VE7TBN

[DanHoug]

everything visually looks "good enough" but proper thing would be to mike for cylinder taper etc. prolly don't need to do that with an engine that was running good and low oil consumption. just hone and clean clean clean.

consider the use of Total Seal's Quick Seat treatment on the cylinder walls plus using a true break-in oil like Driven BR30 for the first 500 miles to really bed those rings nicely.
https://www.dragzine.com/news/sealed-up-total-seals-quick-seat-piston-ring-lubricant/

https://drivenracingoil.com/i-30497749-br30-5w-30-conventional-break-in-oil.html

what grit and composition ball hone ball hone are you thinking? i used a BRM 240 SC on mine for the WBX but i'd call Brush Research to get their advice.
https://cdn2.hubspot.net/hubfs/484035/FlexHone_Resource_Guide.pdf
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[space]

Sodo,
Any chance you can post the pcv line diagram?
I have conflicting info
Thanks
_________________
82 westy
w:
2.5 JDM Subie
Rear discs

[Sodo]

[Franklinstower]

2005 EJ253 Ring Gap - I would "Assume" the same for your block

_________________
'89 Westy - EJ25/22 Frank 4.44 5mt
'75 Miami Blue Sunroof FI Standard Bug

[Sodo]

I will check that, (later today) thanks Paul !
I hear that 2010 has a tiny oil control ring.
It's definitely about the smallest I have seen.
It's 2mm tall.
Smaller than a motorcycle oil control ring.
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'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[Franklinstower]

I forgot the change ocurred in 2010. 2005-2009 outbacks were the same except in 2006 they went to the VVT.
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'89 Westy - EJ25/22 Frank 4.44 5mt
'75 Miami Blue Sunroof FI Standard Bug

[MarkWard]

It's interesting the verticle lines on the pistons show up in the cylinder walls as well. Can't tell if the piston skirts were factory coated or if that is some sort of build up. I also find it interesting that the one piston shows the lines directly aligned with the oil hole in the bottom ring land and the oil ring expander edge is over one of the holes.

Unless you are buying oversized rings that need to be fitted, I'm going to guess you are stuck with the end gaps you get. There is also a formula you can use for determining ring gaps that will get you close.

Top ring, Bore x 0.0045"
Middle ring Bore x 0.005
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☮️

[alaskadan]

Well you're getting right after it. Those are short fat pistons aren't they. When I re ringed / re rung? my engine, it probably had 75k on it. My oil rings were loaded up. Cylinders still had a tad of original cross hatch, and no feelable step at top but likely measurable. I did a light hone to break the glaze, 3 bar hones are cheap. Your cylinders look good. Id be tempted to just put it back together. How about a pic of the smile left by the valves .

[DanHoug]

[MarkWard]

Dingle berry hones have their place. You are at a crossroads. As stated, only serious honing will straighten worn cylinders at the risk of adding too much clearance and resulting piston slap. So, if you have taper or out of round, you are looking at new oversize pistons and machine work.

If the goal is to install new rings, the dingle berry will knock down glaze and give you a cross hatch for the new rings to seat on. This is more of an economy move. Getting the hang of measuring cylinders with a bore gauge does take gaining experience. A machine shop could do it for you. Then decide how you are going to proceed.

Oil rings became narrower and had less tension to reduce friction improving mpg. That yours don’t seem to have a lot of tension would not surprise me.
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☮️

[11BC2]

Save yourself a TON of money, time, and frustration...and bore the cylinders out for the next size piston.

Or, simply install new rings, which is not ideal.
Subaru runs much tighter piston to cylinder wall clearance, and using a dingleberry and re-ringing it will lead to oil consumption

You have been warned.
_________________
1985 Westy Joker EJ253 and Subaru 5spd
1990 ex Bundewehr Doka 1.9 AAZ

[11BC2]

[Franklinstower]

[11BC2]

[Franklinstower]

[Sodo]