Jump to content

What's your oil pressure set at?


Recommended Posts

Just got my plane back from overhaul and the oil pressure is set very high -- it's at the top of the green during cruise and yellow during take off.

Curious what are the consequences of higher oil pressure? Could this prevent camshaft spalling (reason for my premature overhaul) in the future? Is it bad for the crankcase? Bearings?

I'll check the Mooney Service Manual PDF as well to see what is recommended, but curious if there is any wisdom in leaving it as-is or whether to adjust it down.

  • Like 1
Link to comment
Share on other sites

Reasons for High oilP...

Higher viscosity oil than usual.

Different grade of oil than usual.

Lower oil temperature than usual.

Oil Pressure regulator set a bit high.  (Spring controlled valve, adjustable)

 

Challenges Of Too High an oilP...

pushing seals out of their locations?

pushing oil through the seals?

nothing helpful is going to come from too high an oil pressure.

cam and lifter issues come from too many days off more than lubrication challenges...

 

Why oil P is kind of set....with some stability...

The oil flow through the engine is delivered volumetrically by the gear pump and operates in relation to the engine rpm.

The Pressure is generated by resistance of the oil to flow through all the channels in the engine. The last channel at the end of the line is the pressure relief valve... that dumps the rest or excess amount of the oil back towards the sump....

 

PP ideas, not a mechanic... let me know if I got this right...? :)

best regards,

-a-

Link to comment
Share on other sites

Higher pressure at the regulator is more volume through the galleries. The Rod and Main bearings get enough oil but what you do get is more piston cooling oil on the bottom of the piston and more oil to the rocker box and valve guides. 

  • Like 1
Link to comment
Share on other sites

58 minutes ago, Raptor05121 said:

Am I correct in remembering that the IOs have jets shooting oil at the pistons and the Os do not? I don't believe we benefit from the extra cooling

IO-360s have the piston cooling nozzles while most if not all versions of the O-360 do not. Including IO-360L2A in the restart 172s, they are basically an O-360 parallel valve engine with fuel injection. The best of both worlds, parallel-valve derated HP, longevity with the markedly better efficiency of the RSA-5AD1 fuel injection (right off the IO-360).  Bolt that thing onto an M20C and you will have a plane thats cheaper to run than an M20E, a little slower but the same trip burn. Think of your dad's M20C that runs LOP at 1.5 GPH less no loss in speed.

Edited by jetdriven
  • Like 1
Link to comment
Share on other sites

It's the 100 Sae 50 Mineral Oil from Aeroshell that's in the plane now. The pressure is at 95-99 on take off, and then 87-90 during cruise (non engine monitor gauge), just the default needle.

Friday’s flight log shows 92 at takeoff, 86 at high power, and 80 in cruise (2500 rpm) using Phillips X/C 20W-50. I wouldn’t count on your analog panel gauge to be anywhere near accurate.

 

 

Sent from my iPad using Tapatalk

Link to comment
Share on other sites

I run AeroShell W100 (50 wt.) year round based in NC and preheat so that the engine is >60 F before start.

I see 100 psi briefly upon starting coming down to about 90 on t.o. roll and 75+ in cruise when the oil gets to 185+. 

I changed the oil pressure spring to the next heavier gauge a few years ago, I like the pressure to stay in the high side of the green.

 

Link to comment
Share on other sites

Alex- this is fairly normal for overhauls, partially because Lycoming changed the limit to 115 psi, but our POH still has a limit of 100 psi.  Your engine overhaul shop did the right thing and set the oil pressure according to the new specs.  Tight tolerances will also give you slightly higher oil pressure which will probably go down a very small amount in the next 100 hours.

I wouldn't worry about it, but enjoy the knowledge that you will be getting enhanced oil pressure and flow where you need it the most- through the lifters and pushrods to the valves, and a greater chance that some of that oil will find its way to the camshaft lobes.

  • Like 1
Link to comment
Share on other sites

I just put two new cylinders on my IO360 and running Aeroshell W100 mineral oil. The pressure runs at the yellow line if you add full power before the oil temp comes into the green. Once the temp is up the pressure runs at the top of the green band in cruise. 6 more hours of break in for those two cylinders and I will go back to Aeroshell 15/50. BTW: the engine has 2200 hours total time since overhaul!

  • Like 2
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.