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This is my first BMW so im not familiar with what good pressures are for this engine. Im getting about 50 psi on the oil then after it warms up it drops down to about 20 at idle. If I give it some gas it pulls back up to about 40 or so.
Water pressure is about 5 psi or so when hot and its running about 185 to 190f when just sitting there idling, my aux fan never kicks on.
Are these numbers ok?
Oil pressure is dependent on oil temp and engine rpm. Oil takes a long time to heat up because it isn’t a good a heat absorber/radiator and the engine is designed to dump heat into it’s water, not it’s oil. That being said, with oil temp >190deg, I’d expect oil P to be >50psi at red line and >7psi at idle. Ideally both would be 10-15% higher, but less than that would be something to note.
This also depends on oil viscosity by the way. Different xW50’s can vary widely in viscosity. Redline and Amsoil xW50 race oils are ~20% thinner then Brad Penn 20W50. Mobil1 and Valv VR1 are in the middle, with M1 being the thinner.
Coolant pressure is highly dependent upon rpm. As long as the engine is running reasonably cool, I wouldn’t worry about pressure too much. I wouldn’t bother with even monitoring coolant pressure. Just put in a coolant pressure switch that will trigger if you loose coolant and be done with it.