No RPM gage and low oil pressure

At he beginning of the warm engine run-up, my 1965 skyline lost engine oil pressure at 1000 rpm and the rpm gage went dead in the glass. The rpm gage is a recent overhaul 200 hours ago. I could get the oil pressure to come up slightly with a bump in rpm, but no rpm gage. I pulled the rpm cable and it appears normal at both ends. I don't leak any oil. Any ideas to check?

Comments

  • Scott ShererScott Sherer COO Forum Moderator
    Hi and thanks for writing. Regarding the oil pressure; be very careful while you're testing. If there's really no oil pressure you don't want to blow your engine. Have a mechanic check that pronto. Regarding the tach. Unfasten the cable for the back of the tach and start the engine. If the cable is rotating then it's the tach gauge. If the cable isn't rotating unfasten the cable from the engine and check the engine side with the engine running. If the engine side is rotating then the tach cable snapped in the middle someplace. Good luck and let us know how you make out.

    Scott Sherer
    Wright Brothers Master Pilot, FAA Commercial Pilot
    Aviation Director, Cessna Owners Organization Forum Moderator and Cessna Owners Author.

    Need help? Let me know!

  • UPDATE: I checked the tach And the cable, all is fine. Along with my A&P, we pulled the oil pump gears and found that the tach spur gear sheared its mounting pin. The gears in the oil pump ate the side wall of the pump housing. The 5 hour old oil filter caught the particles. We then pulled the engine off the airframe and will replace the oil pump, housing and while we're at it the 4 engine mounts. I'm glad this was discovered on the ground during engine run-up and not over the mountains. Now, to put new checks in the checkbook.
  • Scott ShererScott Sherer COO Forum Moderator
    Great job! You and your mechanic deserve a drink! Sorry about the checks... I feel your pain, lol.

    Scott Sherer
    Wright Brothers Master Pilot, FAA Commercial Pilot
    Aviation Director, Cessna Owners Organization Forum Moderator and Cessna Owners Author.

    Need help? Let me know!

  • It would be nice if you could have shared some photos with us. Today, everyone has a cell phone on their hip, but never think to use it during events like this.
  • Scott ShererScott Sherer COO Forum Moderator
    Thanks for sharing the pics. A picture is worth a thousand words. Quite helpful and educational. Thanks again.

    Scott Sherer
    Wright Brothers Master Pilot, FAA Commercial Pilot
    Aviation Director, Cessna Owners Organization Forum Moderator and Cessna Owners Author.

    Need help? Let me know!

Sign In or Register to comment.