I have a problem with the oil pressure on my 912S, which runs too high after
a while. On the ground and for the first few minutes of flight it seems OK,
about 70 or so --73 is the rated max. Then it starts to vary, jumping around
in the 70-83 range intermittently. It slowly works its way up to 70-94 after
an hour or so at 4900 RPM. I've tried a new pressure sensor which didn't
help. The oil temperature is in the 185-210F range depending on outside
temperature and throttle setting. There is a pressure regulator (spring
loaded ball type) which I will open up and examine; seems like it would be
hard for this to cause the variations I see unless there were debris caught
in a passage or something similar. Anyone know how the regulator, sensor,
filter and engine are connected to the pump output, I.e. what is in series
and what is parallel? Any advice or suggestions on this would be helpful.
An EGT imbalance, 1300 left vs 1500 or so right, occurs at mid-throttle
settings (4700-5000). At full or low throttle the EGT's converge; the engine
seems to run well in spite of the imbalance. (The EGT's are about 1470 at
full throttle - I expected a rise above 1500.) Apparently, there is a problem
in the way I built the throttle cabling: I cut the cables as needed to route
them neatly which resulted in unequal lengths to the two carbs. This may be
the root of the problem or perhaps the cables need to be secured at
intermediate points. Anyone else seen similar symptoms?
John N44EU
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