Oil Pressure System

[Gros Ventre]

I recently installed a separate oil pressure gauge. I was surprised at the pressures I've seen. Note that the 3.5L Twin Turbo PowerBoost engine has two setpoints for pressure. The oil pump is a vane type pump and it has a variable volute (eg there is a flexible strip connected to a solenoid that changes the geometry of the volute). I typically see about 35# at the low setpoint and something above 95# at the higher setpoint. The higher setpoint is high enough that it has caused two bourdon tube type senders (100# max) to fail after about 3 months. As I understand it the dashboard readout shows pressure above 8#. Why the two sepoint pump? I suspect it is because of the turbo feature. Ford wanted to increase the cooling oil flow to the bottom of the pistons at high power. In any event, I ended up replacing it with another gauge system with a 120# max reading. My thinking says be careful... suppose there's a failure that reduces pressure to, say 12# and 30#, the dashboard gauge won't alert you yet the engine may be severely under lubricated. Food for thought. I have been accused of not trusting the PIDS. I trust the PIDS and the Ford Sensors, I'm sure they tell the truth to the computer system. What I don't trust is the programmer deciding for me what I need to know and thus giving a feel-good dashboard presentation until something blows up... I saw something like this with a transmission overheat where the temperature was middle of the band until it suddenly pegged in the red. No damage in the end but did lose a couple of cups of transmission fluid from overheat and expansion to overflow.

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