Good news my boat is running fine, but I am having an issue with my truck. 1997 GMC 2500 with 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 Engine 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?