oil pressure
 

I have a 96 12 valve cummins. When I start my truck and let it idle my oil pressure stays about 40 psi. But when I rev my engine or drive it down the road the oil pressure drops to the edge of the red. My engine isn't making any abnormal noise and the oil pressure light doesn't come on. Its time for an oil change next week, could that be the problem?

nope not unless its very low on oil or super thin. do you have a mechanical or electric gauge. an air bubble in a mechanical line will cause your problem

I don't really know. I was told it could be the pressure sending unit malfunctioning, because my engine seems to be operating fine.

check and see if the connector has oil on it. id get a connector pig tail and replace that along with the press. sensor if the sensor is goin out. hook a mech. gauge up and see what that gauge reads when the one in the dash drops out. I worked on a 98 a while back doin same thing. replaced the sensor and the harness connector, the guy had us put an autometer oil press. guage in the truck too for peice of mind.

That really helps a lot. Thanks guys.