C-90 12F OIL Pressure
Posted: Fri Aug 23, 2019 8:08 pm
HI All,
Just had my C-90-12F that resides in my 140 overhauled. Also up dated the Tach and Engine gauges with an Electronics International CGR-30. Nice instrument and I know some might think it overkill for the aircraft but I like it so far.
In any case the question is that the engine oil pressure has been running lower than I would expect. I currently have about 25 Hrs on the new engine. Before over haul (with the old analog PSI and Temp gauges that are notoriously un-accurate) the oil pressure was a solid 40 Lbs. I have been running 40 weight mineral oil (AeroShell 80)and the pressure was running at 31-33 LBS in cruse with the Oil temp at 172 f . I am running it at 2400 RPM. On start up with the Oil temp at ambient the pressure comes up to 39-40 Lbs as I would have expected, But as the oil temp increases the pressure goes down. And of course as you reduce power (RPM) the pressure goes down. At idle its about 12 Lbs or so. All with in published limits but lower than I would like.
Changed the oil today at the Engine Shops suggestion (Aero Tech, NS, CA) with 50 Weight (AeroShell 100 Mineral )and the pressure is better. 35 Lbs or so in cruse at temp of 172 or so and idle pressure is better about 15-18 LBS. Once I am off the mineral oil I will use AeroShell 15W-50 as I have in the past.
The PSI meets the published limits but I would like to have it a bit higher, say 40 LBS in cruse with normal oil temp. Am I making too much of this, Anyone seen this before ? Is the C-90 pressure relief valve adjustable ?
Just had my C-90-12F that resides in my 140 overhauled. Also up dated the Tach and Engine gauges with an Electronics International CGR-30. Nice instrument and I know some might think it overkill for the aircraft but I like it so far.
In any case the question is that the engine oil pressure has been running lower than I would expect. I currently have about 25 Hrs on the new engine. Before over haul (with the old analog PSI and Temp gauges that are notoriously un-accurate) the oil pressure was a solid 40 Lbs. I have been running 40 weight mineral oil (AeroShell 80)and the pressure was running at 31-33 LBS in cruse with the Oil temp at 172 f . I am running it at 2400 RPM. On start up with the Oil temp at ambient the pressure comes up to 39-40 Lbs as I would have expected, But as the oil temp increases the pressure goes down. And of course as you reduce power (RPM) the pressure goes down. At idle its about 12 Lbs or so. All with in published limits but lower than I would like.
Changed the oil today at the Engine Shops suggestion (Aero Tech, NS, CA) with 50 Weight (AeroShell 100 Mineral )and the pressure is better. 35 Lbs or so in cruse at temp of 172 or so and idle pressure is better about 15-18 LBS. Once I am off the mineral oil I will use AeroShell 15W-50 as I have in the past.
The PSI meets the published limits but I would like to have it a bit higher, say 40 LBS in cruse with normal oil temp. Am I making too much of this, Anyone seen this before ? Is the C-90 pressure relief valve adjustable ?