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Low Oil Pressure Readings

Low Oil Pressure Readings

Dwyer, Stephenson, etc.

Mark Stephenson writes:

Oil pressure was fine, then my observant son noticed that the needle had dropped to 20 psi. At idle it dropped to 0. The oil warning lamp did not light. He brought the car home, and when I checked it, the oil pressure wouldn't rise above 5 psi, but the oil warning light went out as the engine fired. The engine didn't sound like it was oil starved and he needed to get back to school, so I told him to take it. So, I'm guessing that it's either the sender, the gauge, or the wiring in between. I'll start with the wiring -- that will be easy. Failing that, what do the great minds of the list suggest -- sender or gauge?

From Doug Dwyer:

Mark, Easy check on this one. Disconnect the wire from the O/Press sending unit. Turn the key "on", then touch the wire to a known-good ground. The dashboard gauge should swing over to the top of the scale. If it does, then the sender is kaput or your engine is about to "pack-in" (sorry....couldn't resist! Ain't I awful? [grin]) If grounding the wire does not make the gauge move then the gauge itself is on the fritz. Or, as you said, the wiring.

From Rich M.:

Mark, Rather than a "bad relief valve", mine simply needed a good cleaning. Pressure never quite bottomed out at 0 when idling but it also wouldn't reach 40 @ 3000 rpm when warm. BTW during this time the oil light never did come on. Since cleaning, oil pressure has been perfect. A very simple fix, hope your experience is similar.


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