1995 olds 98 regency 3800 II low oil pressure. Intake manifold, upper-lower gaskets,fluids, oil pressure switch, thermostat all replaced. Question = intake manifold failure, coolant everywhere, including the air cleaner box,parts replaced fluids flushed and replaced, currently low oil pressure light that go away when rpm is increased, could any other sensors be contaminated? main issue is low oil indication.
Answer: Coolant everywhere is the key to your problem. There are two possible problems with your Oldsmobile.
1. The oil getting contaminated has caused an internal engine bearing problem. When coolant gets in the oil, this contamination causes the oil to not do it's job lubricating parts. This will also wash the oil from internal parts and cause damage. So, you may actually have low oil pressure. Most likely the cam bearings have been washed clean and now the critical gap between them and the cam shaft is too large, causing low oil pressure to the rest of the engine.
When you rev it up, this increase pressure to a pressure that will turn off the light. Warn cam shaft bearings will not usually give an engine knock like a main or rod bearing. You are going to have to check the oil pressure with a gauge. You install it at the threaded hole for the oil pressure switch. Which brings me to the second possibility.
2. The oil sender switch is bad. (See picture below) On the 3800 engine it is located behind the power steering pump on the lower portion of the motor. Best way to get to it is from under the car. Remove the switch, install the gauge and check pressures.
A low reading would be below 6 P.S.I. If it is above that, just replaced the bad sender that is already removed. If less that this number, you have internal engine damage the it will need to come out and taken apart, inspected and repaired.
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