The oil pressure doesn't change, but the reading on the gauge does. The oil pump is still pushing the same amount of oil thru the bearings. The oil pressure gauge is "recalibrated" by the vacuum pump. Instead of reading from 0 to 100 it is now reading from -10 to 90.
I can understand that the oil pressure does not change. The gauge reading change I am having a little trouble understanding. Can you or anyone explain why? The way I am thinking about it, it the oil passages are full of pressurized oil and the oil sending unit is at the end of that passage, if the pressure itself doesn’t change, how would the reading change? I inderstand the unit is referenced off atmospheric pressure externally
Thx for all the replies.
