OK, here's the story...

 

Newly "partial" rebuilt EA82T. Built on a solid core. Professionally reconditioned gen1 heads. All new gaskets etc. New H20 pump, oil pump, etc. Nothing left to chance.

Maybe a little more history on the "solid core", was it ever severely over heated or left out in freezing weather without antifreeze?... I'm thinking maybe cracked block? Not common on Subies but always possible, and could get water and oil mixed without effecting the compression.

Or compression trouble in #4 (HG or rings, assuming the head rebuild didn’t miss any cracks), and just enough water in the cylinder to pump the numbers up to match the other holes. Try a leak down test, or drain the water (don’t forget the plugs in the heads) and retry the compression test.

Side note: I cant think of any way you could get higher than normal compression from a valve problem, at least not at cranking speed.

Assume nothing, check everything, just some thoughts

Gary

Just throwing stuff out here: Could the oblong O-ring that seals the water passage between the two block-halves be leaking coolant into the case?

I'm not the EA82T expert by any means but I would have to agree with WJM. It seems like you have a bad intake gasket so it looks fine from around the outside edge but the water passage is leaking into the combustion chamber via the intake. Now to explain why there's water in the oil is because water is thinner than oil, its has moved past the rings into the crankcase which would probably also give you a high compression reading in #4....

Pete: If the intake checks out, looks like I'm heading in that direction...

WJM & Cab: I did check the intake manifold bolts and they were nice and snug. It's possible that the gasket is not seating properly or was damaged during installation. The intake is about the only thing that makes any sense right now. Last shot before pulling the motor.

Gary & Snowie:The car has 110k and is all original. The motor displayed all the classic signs of a blown HG before it was redone. It blew h20 out the tailpipe, but there was never any coolant in the oil. I suppose the block could have cracked since then, but it was definitly "solid" before it was torn down.

thanks for the responses guys!!

John