After install of water pump and gasket, intake manifold gasket, and RTV silicone to portions that IN.MAN.GSKT did not cover, as well as the distributor cap, distributor cap rotor, and a new fail safe thermostat, I now have an oil leak on the backside of the motor. After taking the truck on a test drive, I noticed the O.P. was sitting at about 20psi at idle which is normally 40psi, then normally jumps to 60psi while driving, but only jumped to 20psi after a two mile test drive, which eventually fell to below 10psi when idling in the driveway after the test drive. Checked the oil level after the drive and still had a sufficient oil level. Only a small amount leaked out after being parked. The leak is around the distributor somewhere. Any ideas?

 

The seal at the base of the distributor?

 

Did you possibly damage the OP sending unit?

 

The paper gasket was installed with a generous coat of rtv, and as for the sending unit, I will check after work this evening. How can I tell if that is my issue?

 

Thanks for the replies. Turns out it was in fact the sending unit.