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Discussion Starter · #1 ·
This is my first time rebuilding a motor so go easy on me. I'm trying to se my ring gap for the piston rings qnd from what I saw on all data, the rings should be within .20mm to .35mm but when I measured the gap of the ring in the cylinder it read .50 mm. Could I have been misinformed or is there a mistake with the manufacturer of the rings? I bought them to be standard sized. TIA
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To clarify, your old used piston rings have a 0.5mm gap, so the gap may have grown from cylinder bore and piston ring wear. I'm not an engine builder so maybe someone else can tell you how to determine if your cylinder bore is too worn and you need to do something like honing before you put in the new piston rings.
 

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Do you have a brand and part number for your ring set? It would have been convenient to have all of your piston ring issues in one thread.

 

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Is it me or is this new oil ring bigger than the oem because it won't seem to drop into the piston? (New and oem next to each other) View attachment 539906
This is way off topic BUT that is a great picture showing “gummed up” oil control rings.

This is something that causes high engine oil consumption which is often discussed on this forum. Oil control rings with this much contamination can never work as designed.

Thanks for the GREAT photo.

By the way, if the new oil control ring cannot be easily pushed into the piston ring groove then the oil control ring is not the correct part for your piston.

Seagrass
 

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2006 Outback 2.5i manual
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So should I only buy piston rings from the dealer? Or are there other options out there?

In my experience it's best to stick with rings associated with the pistons - in other words, if you have OEM pistons, use OEM rings.

It's hard to tell from your picture, but when you measure ring gap you should press the ring down into the cylinder with a piston, this helps it sit nice and level in the cylinder. I always measure 3 spots in each cylinder (ie top, middle, bottom - with the top being the most important for the compression rings). If you already did do that (I'm sure you did), and you aren't planning on touching the bores, then you really should be measuring the bores with a dial bore guage. You never know how worn they've become unless you measure.

But it's more than just ring gap. Piston to wall clearance is also important, especially when it comes to longevity. Your side skirt coating is totally worn off. Those pistons may rattle, which will wear things down much quicker.

If it were me, I'd be buying oversized pistons and have the cylinders bored out to match them. If I'm going to the trouble to totally open the engine, I always like to start with a fresh bore and hone. The rings almost always end up within spec when you do this, and you're much less likely to have oil consumption issues all while having excellent compression. It will also last longer. Just my own preference that not everyone shares.

Just my .02
 

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Discussion Starter · #12 ·
I may not be correct and this is only from what I've heard but I've been told that these motors shouldn't be bored out because they are sleved motors but if the cylinder sill has the factory cross hatching throughout the cylinder wall then I can just replace the rings. That's just from what I've heard and read so I'm not too sure. But BTW This is my first engine rebuild so I really appreciate the advice. Also this is for a 2005 saab 9-2x with the ej253, so it should be the same parts as the 2005 impreza. Can anyone tell me the oem part number for the rings?
 

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I may not be correct and this is only from what I've heard but I've been told that these motors shouldn't be bored out because they are sleved motors but if the cylinder sill has the factory cross hatching throughout the cylinder wall then I can just replace the rings. That's just from what I've heard and read so I'm not too sure. But BTW This is my first engine rebuild so I really appreciate the advice. Also this is for a 2005 saab 9-2x with the ej253, so it should be the same parts as the 2005 impreza. Can anyone tell me the oem part number for the rings?
Iron sleeved blocks, like found in the EJ engines, can most certainly be bored out (to an extent). Even Subaru makes .25mm and .5mm oversized pistons.

Here is the part number for the STD size...

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At this website they're $135 per set. I assume you need 4 "sets" (I could be wrong).They're pretty dang expensive! 😬

You can definitely get away without touching the bore and just replacing the rings. But, in my experience, you get more life and performance if you at least hone it. It's not required if, like you stated, the bores don't have any visible wear (ie the crosshatch is visible throughout the entire bore).

Again, always doing a bore and hone, even if the bores look good, is personal preference on my part. As long as your measurements are within spec you can absolutely do it without over boring and/or honing.


Anyway, considering the price of the OEM rings, it may be worthwhile getting aftermarket pistons and aftermarket rings. Specifically, Mahle makes them for our engines and they're a solid brand to use.

Here is an option..

Mahle STD size pistons (you will have to add a quantity of 4) :

Mahle STD size rings: (RockAuto is out of stock)

Or I suppose you could take a chance and see if the Mahle rings fit the used pistons you have. You could also try Hastings brand rings (RockAuto has them in stock), I've had good luck with them in the past.

Either way, good luck and let us know what you end up doing! I'm hoping you get it all figured out.
 

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@Diegoc92x were any of your rings stuck like this?
 

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Discussion Starter · #17 ·
Is there a easy way to align the piston rod with the piston to slide the wrist pin in? I'm having trouble lining them up to get the wrist pin in
 
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