B737-800
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Communication Breakdown; Time Pressure; Training / Qualification
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Aircraft; Incorrect / Not Installed / Unavailable Part; Logbook Entry; Procedure
Aircraft arrived late to ZZZZ. While doing my oxygen mask test; I observed a significant drop in oxygen pressure; over 400 PSI. I had Contract Maintenance check the valve on the crew oxygen tank to see if it was open. He reported back; along with his Supervisor; that he found the valve closed and that he opened it. The FO (First Officer) and I then tested both out O2 masks and there was no drop in oxygen pressure.I asked Contract Maintenance if they wanted me to put this in the log book and they requested that I not because of the time it would take to clear the paperwork with Maintenance Control. The crew oxygen bottle had been changed a few days ago. The aircraft flew several sorties a couple of days ago. It is possible that those crews would not have had O2 available if needed. In the future; [I] will record deficiencies in the log book even if it increases delays.
B737 Captain reported getting dissuaded by Maintenance from initiating a logbook entry after discovering the shut off valve was discovered closed on the crew O2 bottle.