The other day my oil pressure dropped from normal. Now at startup I have about 20-30psi oil cold. I used to have 60-80psi oil cold. Can someone tell me how to check the oil pressure relief valve and spring ? Is it easy to do. It looks like by the factory service manual you just unscrew the big bolt near the oil filter and the spring and valve would fall out. Is this correct or am I being naive ? Thanks, any advice would be appreciated. Oil level is fine, no leaks. A lifter or something is tapping on the passenger side of the engine since this drop occurred.