I had my 4.7 completely rebuilt and still have a problem with my oil pressure dropping to zero when the truck is on an uphill angle or when my trailer is connect. reveing the engine brings it back. any ideas I already replaced the sending unit next to the filter.

 

check the oil pickup....might be clogged up with assembly lube that was bad...had it happen on my buddys 360 that i rebuilt

 

The problem started happening before the original engine spun the main bearings, it only happens when the car is on an uphill incline or towing my trailer similar incline. The oil pump is new, rods new, pistons new bea,rings new, lifters new etc. no real noise when this happens either just " check gauges" , i rev the engine and the pressure comes back. today i was on a hill and it continued to happen, i woudl rev and it would come back, then drop again to nothing. Is it possible that the pickup has a crack?

 

possible i reckon...drain the oil, pull the pan and check er out