Oil Pressure

[M20F]

IRAN on the top and bottom about 100hrs ago due to lifters/cam corroding (yes I use Camguard, yes I hate Lycoming metallurgy that isn't my question).  I had this appear a bit early on in break in when I was will using Mineral Oil which I ran to about 30hrs.  Then for the most part everything has been the same as it always had been for 15yrs and give or take 1500hrs.

Yesterday flew KLZU to KDKX and was progressively losing oil pressure.  CHT, EGT, etc. all the normal.  The oil temp was a little hot and then a little cold in both pictures because it is a 45-60 min ride up to 8K with a slam dunk at the end due to mountains.  You can see in the first picture the progressive loss and then an immediate 10 PSI jump, the flight back to KLZU (same day) is the second picture (I also flew KLZU-KDKX-KLZU today and had same 68-72'ish PSI result).

I haven't seen anything sludgy or goofy in the oil, consumption is great, filters are clean, this is new oil with about 6hrs on it (so differing oil then the first time I saw this), etc.  I am guessing some sludge coming apart somewhere?  I open it to the peanut gallery.

 

 

[hammdo]

First, I’d verify the Oil Preasure gauge is accurate with a mechanical gauge tapped in-line (on the ground of course). Also, If no leaks, then verify oil pressure adjustment is good (spring/ball are correct and good), checking oil cooler flow for any blockage. I’m assuming the oil pump gears AD has been accomplished at some point, just to rule that out.

Turbo I’m guessing? May need to check that out also if oil is used for that.

Were the main bearings replaced? I’ve seen oil pressure drop if smaller bearings were put it but, that would be absolutely the last item to verify.

If you’ve read ‘Fly The Engine’, you’ll get some great insight on these lyco engines…

-Don

[MikeOH]

I'd leave it be.  I have a high-time (2700 hour) engine and oil pressure runs in the mid-60s with higher oil temps (around 200 in winter, +220 in summer).  It's been that way since I purchased 7 years ago with 2100 hours. NA IO-360A1A

[A64Pilot]

If the gauge confirms good and if that’s below the green I’d be concerned, but personally before I started tearing into things I’d fly it with both gauges to be real darn sure the ancient stock gauge isn’t flakey. I’ve seen tens of thousands spent when all the problem was the gauge, it was a temp gauge but still it read incorrectly.

If it’s in the green, then well sort of by definition it’s OK.

[cliffy]

Green is good, Red is bad   The old days had everything at specific numbers  (Boeing 727 training vs AB 320 training  :-)

We used to fly for years with only an oil pressure gage and a temp gage then we got EGTs and started to worry about 

50 degrees difference in EGT THEN we got engine analyzers  and now we worry about 10 degrees ?

We flew Cherokees by leaning to rough and enriching to smooth running all day long. Same with all small a/c before analyzers came along. 

Perhaps we worry too much these days with 21st century electronics and 1945  engines.