Ever since getting the overhauled engine (Lycoming 0-320-E3D), I have
high oil pressure at full throttle for the runup and takeoff. I don't
recall it ever making it to the red line until the last year or so and I
have put 800 hours on it. It was always just below the red line at the
first (0 SMOH) full throttle runup of the day. Now, it has moved up one
needle mark to sit right on the red line at 100lbs or a wee bit to the
left and not quite on the line. Idle pressure is just inside the green
(60lbs) and cruise is right in the middle of the green arc - both normal
for this engine. The previous engine never went this high because it was
pretty worn when I bought it and got worse until we finally swapped it
with an overhauled unit.

I am also noticing a slightly higher oil temp lately. The former engine
and this one would be rock solid on 180 degrees until the outside temps
went higher than 85 or lower than 55. Now, anything over 70 degrees and
the temp is a needle mark or two higher than 180 degrees. Under 65
degrees outside and the oil temp is just under the 180 mark.

Could these two things be related? They appear to have surfaced at the
same time. Clogged oil cooler? It IS 33 years old and has never been
cleaned out. A partially clogged cooler might explain why the idle and
cruise pressures are normal, but FT is a bit higher. It also would
explain the temps being a bit off in both directions. When the oil is
hot, the pressure will not go up to the red line. This would also
suggest something is restricting the oil when cold.

I believe the 2 oil controls (pressure and temp) are independent. The
Vernatherm and oil pressure relief valve are separate in this engine if
I recall. If true, the only thing common to both is the cooler.

Or, are these gauges inaccurate enough to account for this drift?

Any ideas?

Mike