Hangar Flying => Hangar Flying => Topic started by: aaronh on May 23, 2005, 07:48:28 PM
Title: 0-235 low oil pressure
Post by: aaronh on May 23, 2005, 07:48:28 PM
I recently flew from colorado to southern california, then over to las cruces for the hotglass flyin. A total of around 16 hours of time was put on my 0-235 longez. On the flight from california to las cruces, I noticed lower than normal oil pressures. I normally run between 65-95psi, and even up to 100psi when the oil isn't yet hot.
On runup I saw 55-65psi. Since my normal colorado start is much cooler than the 80+ deg it was at rosamond, I attributed the oil pressure to thinner warm oil. Shortly after takeoff I noticed the oil pressure ran 35-40psi. I was very concerned and monitored it closely, almost deciding to put the plane down at the nearest field. I began thinking I had an instrument issue because the oil pressure was steady (not bleeding off), the oil temperature was steady in normal range (~180F), CHT is normal range. I continued my 2 hour leg to casa grande, oil pressure stayed steady at 35-40. I checked the oil, it a tad low, but exactly where it should have been after the 6 hour flight from CO to CA. I topped it off and continued on. The oil pressure was again 35-40psi the remainder of the trip. At las cruces, I pulled the cowls off and checked the oil pressure sender (dry as a bone). Electrical connections looked good. The engine was good and clean. I definately wasn't loosing oil. I flew the ez back home a couple days later... seeing the same oil pressure 35-40psi.
I had a couple guys tell me that 35-40 sounded great, but after getting home I confirmed lycoming says normal operating range in cruise is 60-90psi for the 0-235. So either the instrument is failing (I think this is unlikely), or something else changed.
Could the oil pressure relief valve get stuck open? I would guess I would see lower than 35-40psi if this were the case? Any other theories?
I use Aeroshell 15w50 semi synthetic.
Thanks for any ideas,
Aaron
Title: 0-235 low oil pressure
Post by: Drew on May 24, 2005, 07:41:50 PM
Check the gauge first. Borrow a direct reading oil gauge and plumb it directly to the engine (remove the electrical sender and plug it in there).
Title: 0-235 low oil pressure
Post by: cozybob on May 27, 2005, 09:46:34 AM
Suggest you check the oil pressure relief valve. I had an experience on my O320 where a small metal chip was caught on the valve seat and was holding the relief valve slightly open. It exhibited similar low oil pressure symptoms.
Bob M. Cozy N342RM
Title: 0-235 low oil pressure
Post by: aaronh on May 28, 2005, 07:09:02 PM
Thanks guys. I cleaned out the pressure relief and seem to be running back to normal (slightly lower but its a lot warmer out now).