GMC Repair: Oil Pressure Problem, chevy silverado, cam bearings

Question
I've got a 1989 Chevy Silverado pickup (2 WD. 5.7 liter V-8)
that overheated on me one day on the expressway. I
replaced the thermostat, replaced the coolant and
everything seemed fine. Since the engine got so hot I also
changed the oil and filter. For the last couple of weeks the
oil pressure starts out at normal when the truck starts, but
as it is driven the oil pressure starts to drop. After 15 or 20
minutes the oil pressure at idle causes the "check gauges"
light to come on. I thought maybe there was debris in the
oil so I changed the oil again, but it didn't seem to affect
the problem. Any ideas?

Answer
Hi Jeff. You will need to install an oil preasure guage in place of the electrical unit to get an acurate reading of actual oil preasure. If the oil preasure is indeed low then you have a problem with the bearings such as main bearings, rod bearings or cam bearings or you have an oil pump problem. You may also check the pickup screen on the pump for debris.