I have a 1994 Chrysler Lebaron. The issue I’ve been having is for the last two weeks, my oil pressure gauge starts very high(out of normal range), and stays there for a very long time. Whilst it’s at the highest possible level, the engine starts to heat up, until the gauge goes into range. This all happens without the car moving. If I leave the car on for 30 minutes(without moving it) the gauge goes into normal range, and for the most part operates normally. I have disconnected the Compressor’s belt, in order to be able to turn on the engine fan from inside the car. As long as I keep the fan on, the engine stays cool for the most part.
I have considered that it was sludge, as it would soften as the engine heats up, but I have done an engine flush(machine), and the issue continues.
So far every mechanic I take it too, acts like it’s impossible for the oil pump to have any issues, and claims it’s normal behavior, which it’s not.