Oil level and pressure

[PTK]

M20J, IO-360-A3B6D.

Changed oil and filter approx.10 hours ago. Serviced with 8 qts of Aeroshell 15W50 and Tempest oil filter. Oil pressure has been right in the middle of the green band.

Last flight I noticed oil pressure was slightly lower than the middle of the green. Closer to bottom of the green. This corresponds to ~10 hours on the oil and a level of 7.5 qts on the dip stick. 

Is this consistent with what you guys with this engine are seeing? Are you seeing the oil pressure drop off slightly from the middle of the green at around 7.5 quarts? Does your oil level and pressure correlate similarly?

Just curious.

[Bob - S50]

Oil pressure is inversely related to oil temperature.  Things that affect oil temperature are OAT, IAS, and oil quantity (as it decreases, temp will rise a bit).

[Oldguy]

No correlation on oil level and pressure on mine. With 7.5 qts. you should be fine. Pressure will drop with temp, as Bob notes, but I would not think 0.5 qt. down would cause a noticeable decrease. Any chance you have the engine monitor info from the flight? Maybe OAT and oil temp?

[PTK]

I will post it as soon as I get it. 

[ArtVandelay]

Wow, I know would blow out the the oil level down to 6.5 qts in a hurry. I have JPI, my OP varies from 70-80, depending on RPM.

[Andy95W]

Do you do Touch-and-goes?  I've heard that can be the cause of low oil pressure.

No, wait- reading about touch and goes raises your blood pressure.  My bad.

[Bartman]

6 hours ago, Andy95W said:

Do you do Touch-and-goes?  I've heard that can be the cause of low oil pressure.

No, wait- reading about touch and goes raises your blood pressure.  My bad.

They are no longer discussing touch and go,s.now the few who remain active are discussing how much HORSEPOWER a 747 creates. So far, it's somewhere between zero, and a whole lot. 

[HRM]

Speaking of oil, here's my situation...

So, just before annual I have a heavy drip over the nose wheel. No noticeable oil loss on the stick but enough to have wifey saying "oooo...look!' when she saw it (and she never flies in it).

My IA asks before I take her to him (The Mistress, not the wife) if there are any squawks and I tell him that the oil leak must go.

An AMU and an R&R on #4 later with new pushrod and the leak over the wheel is gone.

Go down to the hangar Saturday (after getting plane back Friday) and notice fresh oil on the nose wheel door (pilot side). I wipe it off and attribute it to post annual residual 

Fly for an hour, started on two blades, everything perfect, new donuts yield a squeaky landing, push her back in the hangar and...

Took photo, contacted IA (in Reno for air races) and left (commercial) for Orlando--no time to pull cowling and look. 

So, for two days I have been fretting over this, but then I wondered if this might be the symptom of a loose oil drain fitting--I have one of those quick valves on there and I am thinking that it may not have been wired after the oil change. I can't even remember if it gets wired. Would this look like this?

[ArtVandelay]

I have an oil leak there as well, my AP look at it and said it's coming from the oil pan seam, apparently this is common as engines get older. I might try to address it in upcoming annual, hopefully I just need to tighten a few bolts. But mine is not as bad as yours appears to be.

[HRM]

22 minutes ago, teejayevans said:

I have an oil leak there as well, my AP look at it and said it's coming from the oil pan seam, apparently this is common as engines get older. I might try to address it in upcoming annual, hopefully I just need to tighten a few bolts. But mine is not as bad as yours appears to be.

Thanks, a good place for me to look when I get back and pull the cowling. Her 52nd birthday is coming up next month, so she's definitely not getting any younger.

[carusoam]

Following on Harley's thread creep...

Hard to get squeaky landings with that much oil on the landing gear... 

Chasing an oil leak ideas...

• clean engine
• Use a powder to find the location
• Use Black light dye in the oil

My O360 oil leaks.... (easy to fix)

• Valve rocker covers gaskets
• oil return lines, so many hose clamps on old hoses
• the quick oil drain didn't seal right.  Always a drip hanging

Other leaks to look for...

• Front shaft seal
• seal at the prop governor
• seal on the back case
• seal on the oil pan
• seal on the oil fill tube

Leaks you hope you don't have...

• between case halves.  Silk thread seal.
• cracked case up around the cylinder bases.

Air flow through and around the cowling spreads a small amount of oil everywhere.  Finding the leak source may be complicated by flying the plane...

PP ideas only, not a mechanic...

Best regards,

-a-

[Oldguy]

2 hours ago, HRM said:

So, for two days I have been fretting over this, but then I wondered if this might be the symptom of a loose oil drain fitting--I have one of those quick valves on there and I am thinking that it may not have been wired after the oil change. I can't even remember if it gets wired. Would this look like this?

Quick answer - yes, a quick oil drain leak would look exactly like this - I know from experience. The drain itself is spring-loaded with a twist-and-lock style opening for draining. As it ages, the spring holding it closed can weaken, and you can get something like what you see. Could be as simple as making sure it is fully closed, wiggling it a bit, or draining again because something got caught in the opening preventing it from fully closing. All of those options are so much better than replacing the quick drain itself.

[Bob_Belville]

Anthony's list matches my experience, mostly limited to my one IO 360, and is in the sequence I'd look for.

I have deal with all these, some more than once in 6 years:

Valve cover gaskets,'

oil return lines,

filler tube gasket (at bottom of tube).

Quick change valve seat,

prop governor gasket,

Oil "leaks" may come from oil breather line, spills from filter change, adding oil, r&r oil screen or other rmaintance

I protect the mags and spray about everything below and behind the baffles/seals with Gunk and rinse thoroughly with a water hose, then run. It's nearly impossible to find anything on a dirty engine 

 

[HRM]

A big thanks to all for the hints. In a freaky sort of way I am looking forward to getting back and pulling the cowling!!!

The other thing I noticed in reading through the suggestions is how a similar thread might be found on the geriatric urology board--I hate getting old.

[Andy95W]

@PTK- Sorry about the thread drift, Peter.

In less than 24 hours we ignored your problem and solved somebody else's.  The power of MooneySpace!

[HRM]

9 hours ago, Andy95W said:

In less than 24 hours we ignored your problem and solved somebody else's.

Indeed, mea culpa. I saw the thread drift and thought I might get it back onto an oil problem 

[carusoam]

Summary for Peter's OP...

Pressure is defined as the resistance to flow.  So, lower pressure is indicating there is less resistance to flow. The following are things to consider that may be decreasing the resistance to flow

• 10 hours on fresh 15W50
• 8qts in
• 7.5 qts remain
• oil pressure slightly lower than usual
• Oil pressure is related to volumetric flow and viscosity. (And, the geometry of the oil's path, including wear)
• Volumetric Flow is provided by a gear pump and a pressure valve at the end of the oiling process. Aka end of the oil gallery(?)
• the gear pump rpm directly changes with engine's rpm, but the oil pressure is controlled by an oil control valve..(?) where excess oil is dumped back to the sump...
• viscosity is provided by the oil's chemistry and structure, but modified by temperature.  Hotter oil is less viscous...
• OAT and oil cooler effectiveness can affect the oilT.  Might want to check the OilT and see how clean the fins are on the oil radiator.
• some odd excess use of oil happens when the oil pathways open allowing more oil to escape earlier on in the oil gallery. These are the areas that open up at the end of the engine's useful life, TBO...
• Engines are designed to have an excess amount of oil, so it would take excess wear to allow too much oil to escape back to the sump.
• sounds like very little oil has left in the 10 flight hours. Most IO360s use a At every 10 hours or more...
• There is some oil pressure related to the level of oil in the sump.  It would be measured in feet of water column. One psi is about 2' of water column, now adjust for oil density...
• oil additives can have a significantly strong effect on the oil's viscosity, but Peter doesn't use those does he? 

Does that oil control valve have accessibility?  Might be time to remove and clean(?)

Is it an instrument problem?

Is it an instrument ground problem?

Does the oil pressure change when the OAT is hotter or colder?

Does the oil smell like exhaust, or have a dark color?  (Oil can get modified and decrease its viscosity)

 

PP thoughts on engine oiling... not a mechanic.

Best regards,

-a-

[Mjknick@gmail.com]

Lycon has a solution to leaky Lycoming Engines they cut a grove in the case halves in order to put a bead of sealant in it that also acts as cushion between halves. Very good upgrade.


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[Guest]

Grooves cut into the case above the camshaft bearings eliminate oil leakage at the case halves.  Normal case sealant and a silk thread are still used to seal case halves.

Clarence

[HRM]

OK, I think I found the leak. Solutions? Note drips on #2 fins.

[KSMooniac]

OK, I think I found the leak. Solutions? Note drips on #2 fins.

I'd check the oil drain back lines and rubber hose joints under the cylinder, and also thoroughly check to make sure you don't have a crack in the cylinder. Might have to thoroughly clean it first then re-inspect.

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[HRM]

Just now, KSMooniac said:

I'd check the oil drain back lines and rubber hose joints under the cylinder, and also thoroughly check to make sure you don't have a crack in the cylinder. Might have to thoroughly clean it first then re-inspect.

Gonna need an A&P, now out of my wheelhouse. At this point I am just trying to minimize diagnostic time and learn things about the engine, thanks!

[ArtVandelay]

I would think about replacing the ignition wires while you at it.

[Hank]

1 hour ago, teejayevans said:

I would think about replacing the ignition wires while you at it.

His don't look too bad except where they are bent over at the plug. This is my old set:

And the new ones with prefab 90° elbows:

And yeah, just noticed I need to reroute the lead to #3.

[Hank]

Harley, a common leak is at the bottom of the oil filler tube. It should be tight, with no rotation. Mine's getting new gasket & safety wire soon, it twists almost 1/8".