IO360-A1A Oil Max. Pressure

[Igor_U]

There's another thread regarding low oil pressure but I have the other question:

I have a rebuilt engine in my M20F that consistently has a high oil pressure, especially when cold. Temps in PNW are not really hot and quite often on a takeoff roll (oil temps 100F) it would go into red (100 psi). 

I have newer EI CGR30P engine monitor with oil pressure transducer and I believe it's accurate. In cruse, in a cool (standard) day pressure would go into yellow (90 psi) and in summer is just bellow 90 psi (in green). Idle on the ground, it's not uncommon to start with 105-110 psi (even more on a cold day) and go bellow 100 psi only after few minutes. On a takeoff after 10'+ of taxi, runup and wait, pressure always get to 105+ psi

I understand that Lycoming has an oil pressure pickup at different location then Conti and there's SB increasing max pressure to 115 psi but EI flashing warnings at the startup and takeoff is annoying.  But some people say oil pressure  can't be too high...

So, question is: my annual is in 3 weeks so should I ask my IA to reduce the pressure (remove the washer) on the engine or not? 

Engine is running great, no oil leaks and uses 1 qt over 10-12h.

 

Thank you.

[A64Pilot]

It won’t hurt a thing to reduce it to the middle of the green, myself I like it at the top of the green.

The fact that you can produce high pressure with hot oil means your engine is good and tight, nice problem to have.

Where I worked we used a dead weight tester to test EI’s pressure transducers as we used them for engine torque, for example max tq for a Pratt T-34 was 58.7 lbs, so since we were talking .1 lb accuracy we needed to calibrate them in the MVP-50T, the E.I. transducers were spot on, and at least as important they were repeatable too.

I had an MVP-50P in my Maule, I had 14 temps. 6 cyl head, 6 exh, 1 oil and 1 OAT. After sitting in the hangar for a couple of days I could turn my battery switch on and all read within 1 degree of each other.

[N201MKTurbo]

I’ve a.ways set it to the bottom of the green when hot. I find it uses lass oil that way. BesIdes, if it is right on the bottom of the green, it gets your attention when it isn’t right. When it is in the middle of the green, it can move quite a bit without you noticing it.  

[jetdriven]

The problem with being at the bottom of the green is you have no margin in case you run a quart or 2 low it goes into the yellow and really Lycoming says to tear the engine down when you get below 55 or 60 psi.

[KSMooniac]

Unless the EI warnings bother you, I would leave it. I still get an occasional flash on my JPI, especially when colder, but I want it to run 89 psi in cruise. Higher is better on a Lycoming to get oil to the rockers and valve stems. They raised the redlines on the restart Cessnas (with Lycomings) but never publicized why... But it was done for a reason!

Sent from my LM-V405 using Tapatalk

[Mooney Dog]

18 hours ago, jetdriven said:

Lycoming says to tear the engine down when you get below 55 or 60 psi.

Do they really? huh... TIL.

[Shadrach]

19 hours ago, jetdriven said:

The problem with being at the bottom of the green is you have no margin in case you run a quart or 2 low it goes into the yellow and really Lycoming says to tear the engine down when you get below 55 or 60 psi.

Not doubting you, but would be interested in a link to the relevant Lycoming doc that specifies tear down.

[Igor_U]

18 hours ago, KSMooniac said:

Unless the EI warnings bother you, I would leave it. 
 

Yes I am leaning towards leaving as well.  Not that it really bothers me but red light flashing gets the attention of my passengers as well.

 

today we flew flamping to Cavanough bay 66S and temps at 9500 were 54F. Oil temps at cruse was 189 with pressure 89-92 psi (yellow). It’s the takeoff where i get 110+ psi flashing red in my monitor 

[Browncbr1]

I would adjust pressure down quite a bit to cruise at about 75psi.   If I’m using 100w oil, I don’t take off until oil temp is at or above 160. With multigrade, I take off at about 140 degrees.   This helps keep oil pressure at or below 100psi. 
 

also, not sure about continentals…. I think the OEM gauge takes oil pressure reading at the end of the gallery?   Lycoming have two at the beginning.  I may have a little bit of calibration error, but it seems the upper port on mine (hooked up to jpi) reads slightly higher at times than the lower port (OEM garwin gauge)

Edited July 16, 2022 by Browncbr1