Idle after engine run 1000 165 26 Just 1 PSI over minimum allowable with oil at only 165 F
This is a warning that something in your oil system is sub-optimal and headed in the wrong direction. On a newer, healthy engine the warm idle pressure will typically be over 50 PSI. This is the toughest area (warm idle) for the the system to deliver high pressure, so it is the first to warn of wear or problems in the oil delivery system. This is why lyc lists an acceptable idle pressure level. Most common causes are wear in the oil pump or worn/loose crankshaft or rod bearings. Do you clean your sump screen often? blockage at the oil system inlet can create reduced flow, but usually shows low pressure at higher RPMs as well.
No serious danger until the higher RPM readings start also dropping, assuming bearings. However, addressing this early may reduce the overhaul cost if it turns out to be bearings. However, some issues in the oil pump can be such that they could fail completely at any moment, resulting in a complete lack of oil flow. That is a major flight risk. Oil pump sits on the accy case, so relatively easy to rule out without too much work or an engine teardown. If this has been slowly degrading for 100's of hours, risk is likely low for short term, catastrophic failure. If this showed up out of the blue, you should ground your plane and figure it out, as short term catastrophic failure is much more likely.
The real monster in the closet is the oil pump. Lyc has had several ADs on oil pump wear problems that resulted engines seizing. If bearings, they will continue to wear and provide plenty of warning before oil stops flowing adquately. Not the case for oil pumps. Wear issues can quickly lead to a locked up pump and no oil flow. It 'really just two gears in tight mesh with very little external clearance. If a chunk breaks off an impeller (i.e. gear), it often locks up or shred the aluminum housing.
It is likely to continue to worsen,. Could take a few flights and could take 100's of hours, depending upon the cause.
An analysis of the origin of debris found in the oil filter can help to determine which part is failings. Bearings compounds are different than the oil pump impellers.
Do you cut open your oil fiter at every change. A common cause for rapid bearing wear on a lycoming is spalling lifters (large chunks break off the lifter faces and then chew up the brearing when they reach them) and there should be evidence in the filter if that is happening. Several recent threads with pictures.
Larry
