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Old 07-13-2021, 07:01 PM   #4
Elbert Bass
Scooby Specialist
 
Member#: 283429
Join Date: May 2011
Chapter/Region: South East
Location: Down yonder.
Vehicle:
2016 Fuji Sunfire 03
Silver

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Quote:
Originally Posted by Hobbes2.2 View Post
Yeah, that doesn't sound fun. Good to know, thanks for info.

So I do end up need a new block down the road, is there anyway I can verify that the new block won't end up having the same issues? (I guess what I'm asking is: is this oil leakage a ware-and-tear on the block over time, or an actual defect in the block?)

I've read a couple places that say the issue stems from poor quality factory oil rings, and others that say it's a defect in the block itself.

I've also read that Subaru supposedly fixed this issue later in the FB20B line, but am getting conflicting dates on said fix. Some sources say 2014, others 2016. Oh nm on this last one, I just found Blktrax's post on that from back in 2018.

"Block Part# Interchange
10103AC650 = 2014-2015MY Forester & 2013-2014MY Legacy & Outback
10103AC760 = 2013MY XV Crosstrek 2.0L CVT & 2013-2015MY XV Crosstrek 2.0L MT
10103AC750 = 2012-2013MY Impreza 2.0L CVT & 2012-2015MY Impreza 2.0L MT
10103AC660 = 2011-2013MY Forester

Everything after these models have the revised rings from the factory." (cred. Blktrax)

But my curiosity about the block defect vs crap oil rings still exists. It feels like a chicken/egg thing from my knowledge-limited perspective, one problem would lead to the other overtime? Any insight on this? Also curious, any idea what about the oil rings is bad (was it just poor quality material, or poor manufacturing Q/A, or other)?
Same question for the block defect: what was said defect?

Thanks again!
Any new or reman short block currently sold by Subaru will have the revised rings. The issue was ring tension. In order to reduce friction Subaru reduce both ring thickness and ring tension in FB engines compared to EJ engines. So much so that in Subaru engine class you could unbolt the rod caps on a new engine, turn the block on it's side, give the rod a nudge and the piston would slide right out of the block. Even a worn out EJ would not do that.

They also went to a lighter weight oil (0w20) so the rings wouldn't "float" and pump oil into the cylinders. The problem was the early engines had so little ring tensions the rings still "floated" and pumped oil into the cylinder where it was burned. They tried replacing rings but they had a problem with techs breaking the rings or scoring the cylinders while installing them. They finally went to replacing short blocks. There never was a block defect, just the lack of "old school" mechanical experience of Subaru dealer techs.
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