Engine Mechanical problem
1997 Chevy Cavalier 4 cyl Front Wheel Drive Automatic 200000 miles
Was passing a truck on a hill and the trans downshifted from 4th to 2nd and the engine red-lined (half way in the red) for a couple seconds till I could get the cruise control off. It started what appears lifter noise, sounding like a diesel when warm and idling. Once above 1500 rpm the noise goes away for the most part. When cold the engine sounds normal. Cold idle oil pressure is 50 psi or higher, 75 at 1500 rpm or higher; warm it's 20 to 40. Could it be the pump or am I gonna have to break down and pull the cams, or could it be something else? Am thinking of getting a used engine with 98k for $500 as this has 200k.
With out hearing the noise it is a bit hard to say one way or the other, but the oil pressure readings you report sound fine, you may have stressed a lifter or even bent a push rod, you can do a valve lift test to check a push rod, but I would be thinking more on the lines of a lifter, you could start with an oil flush using a good quality flushing compound just in case it is some loose carbon fouling a lifter, otherwise it is the head off to check lifters.