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Old 06-03-2011, 12:50 PM   #4
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Member#: 120273
Join Date: Jul 2006
Chapter/Region: SWIC
Location: AZ
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I got a spare NA 2.5 short block from a fellow member on here. I promised to trade him alcohol for it, but I never delivered the goods, so this motor was free. brocksdad is a sucker.

Either way, this motor also had rod knock despite having brand new bearings and despite having only run for a minute or two. What was strange is that this motor was from a 1997 Outback, which should have made it a Phase 1 DOHC 2.5. However, upon teardown, I found that the case and the crank were definitely Phase II as the thrust bearing was on #5 instead of #3 like the Phase I blocks. To compound things, the pistons in this block were definitely the old Phase I square relief ones. My guess is that this car had a warranty replacement motor at some point and Subaru repaired it with the updated block design.

Whatever the case may be (no pun intended) on the doaner motor, it looks like I can use the block and the crank for this build. This saves me the trouble of driving down to Tucson and pulling the motor from the RS only to drag it back up here for disassembly and rebuild.

Here are some pictures of what I found.





As you can see, the bearings are shot. It seems that the bearing in the rod end (not the cap) on each took the brunt of the damage. This makes sense.

What would you guess caused this? Lack of assembly lube? Not priming the motor? Improper clearances? Improper torque on the cap bolts?
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kpluiten is offline   Reply With Quote