oil pressure drop

[clarkmiller]

New to forum. 05 XC70 235000mi. I picked this up cheap. One cylinder low compression. Burnt valve. Planed head, replaced all valves, pcv box while all apart. NOW- Runs great until you drive it down the road for 10 min, and I get the stop safely no oil pressure message. Sooooo, we flushed the motor, dropped and cleaned oil pan and pickup tube, installed new filter,and Castrol synthetic 10-30. New oil pressure sensor. Same message. The motor runs very quietly, excellent power, and stays quiet after message.

I'm at my wits end. Any ideas?

[vtl]

Oil pump, it has a pressure relief valve that gets stuck.

Also did your try to move the crankshaft while the pan was out? Could be the bearings are worn.

[SuperHerman]

vtl's suggestion is solid. Check that out.

You need to check your work specifically the oil pan o-rings. Another question is what type of sealant did you use on the pan and head? Did you use the correct anaerobic sealant or RTV? If the latter that could be the cause as the wrong sealant can cause blockage and/or break away fragments that cause the same.

[ignatz]

Maybe, pull the oil pressure sensor and tie in a mechanical pressure gauge. It should confirm good or bad.