Low Oil Pressure At Idle

[Not Twice]

1997 GMC 2500, 5.7, 150,000 miles. After motor is warm my oil pressure is dropping to 10 psi or less at idle with truck in gear and my Check Gauge Light comes on. If I shift to neutral the RPM goes up about 150 more RPM’s and the oil pressure goes to about 10 psi and the light goes out. When running the oil pressure is pretty solid at 40 to 45 psi.

 

I have put a mechanical oil pressure gauge on to verify the accuracy of the electronic gauge and it validated that the low pressure is real. The mechanical gauge would sweep up and down as expected and showed 40 to 45 psi as well.

 

Any thoughts to what it may be? Oil pump screen clogged? Needs new pump? Engine is tired? Can I remove the oil pan and change the pump without lifting the engine or removing steering components?

 

[Zembonez]

Wear in the cam journals (and other surfaces) is likely what the actual problem is. As they wear, the extra clearance drops pressure. It's not alarming but I'd probably go to a high capacity oil pump and obviously clean the screen up. Not too hard of a job on a 350. This is not really uncommon on higher mileage 350s. With a new pump, I'd bet your hot pressure at idle would double.

[Rowdynready]

1997 GMC 2500, 5.7, 150,000 miles. After motor is warm my oil pressure is dropping to 10 psi or less at idle with truck in gear and my Check Gauge Light comes on. If I shift to neutral the RPM goes up about 150 more RPM's and the oil pressure goes to about 10 psi and the light goes out. When running the oil pressure is pretty solid at 40 to 45 psi.

 

I have put a mechanical oil pressure gauge on to verify the accuracy of the electronic gauge and it validated that the low pressure is real. The mechanical gauge would sweep up and down as expected and showed 40 to 45 psi as well.

 

Any thoughts to what it may be? Oil pump screen clogged? Needs new pump? Engine is tired? Can I remove the oil pan and change the pump without lifting the engine or removing steering components?

 

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I am having the same issue and I have a 1989 C1500 - I get blue smoke at start up and I know my valve seals are bad but it seems to be a bigger job than I can handle. I did get a high flow oil pump that I hope to replace tomorrow and I will post if that helps. Good luck with your truck!