"Houston, We have a Problem" Help!

[gl1674]

The line pressure test involves attaching a pressure gauge (similar to tire gauge, but with 5 feet hose and a proper adapter to a tranny).
There is a test port on the left (driver side) of the tranny.
It is plugged with a bolt. One has to get under the car, remove
the bolt and connect oil pressure gauge. Access is rather hard,
exhaust pipe is in the way, so the car has to be cold.

The exact port location and readings are in the service manual.
Roughly it should be 60psi at idle in D/N, 80psi at idle in R,
raising to above 150psi if engine is revved up.

You can do it yourself if you can find a gauge and have ramps.
I bought my gauge at ontool.com, I paid around $50. It is a universal gauge with adapters to all transmissions and can also be used to check engine oil pressure.

Any transmission shop that specializes on transmission rebuilds will have the tools to do this test (whether they will be willing to do this for you is another story). Shop prices I have no idea about, my guess they would charge about 1 hour labor for diagnostics.

Subaru dealer may not agree to touch transmission at all. Our local dealer says SOA does not allow them to do so, but I suspect they just want money from transmission sales, not from small repairs.

Solenoid A is a part of a pack of 4 solenoids. The cost is around $200. They are available via subaru dealerships. Replacement involves draining ATF, removing bottom cover of the transmission and removing the valve body. Nothing hard, but very tedious and ATF is dripping down. Paper gaskets in the valve body tend to get brittle - it added another $20 to my repair cost and another couple of hours of work. No idea how much a shop would charge for solenoid replacement - 3-4 hours to match the price of the part?

Why it only slips in high gear? Good question. Several explanations possible:
1. This is the only gear where you can drive with a throttle more than half open for any extended period of time so you have time to analyze revs.
2. You may not see 200-400rpm slippage in lower gears - it can be masked by normal slippage in torque converter
3. We don't know what component slips - it may be the torque converter lock-up clutch and it only works in 4th gear.