In Reply to: Adnan e34 oil presure prob posted by roger on August 01, 2001 at 18:28:14:
How did you determine that the valves are okay? It is almost impossible to tell without dismantling the canister.
Yes, the o-ring seals off a bypass passage that permits the canister to drain when the bolt is pulled. If the o-ring is defective or not seating properly, it'll allow drain back.
A simple test - remove lid of canister and replace the bolt (with o-ring). Remove filter element and pour some oil into the canister and let it sit. If it drains, you'll be able to tell whether it's the valve or the bolt by the oil level that is left standing.