Mechanics

OIL PRESSURE

1990 GMC C1500 • 300,000 miles

I had low oil pressure and changed my oil pump. Now my oil gauge reads max. Is this normal and what is normal operating range for the oil?
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Nick2586
July 16, 2012.



Normal is around 40 - 50 psi. Expect less with 300,000 miles. Worn crankshaft and connecting rod bearings are much more common causes of low oil pressure than pumps, but you may get lucky.

As for the gauge, unplug the sending unit, then check the gauge. If it still reads max, a wire is grounded; possibly pinched between something you reassembled. We all do that sooner or later. If the gauge goes to 0, try a new sending unit. Remove the old one first, then crank the engine about two seconds without starting the engine. That will wash out any debris that might be lodged in the passage, but it will make a small mess on the floor too.

Caradiodoc
Jul 16, 2012.
Thanks

Tiny
Nick2586
Jul 16, 2012.