No Oil pressure w/ new used cooler
 

My 1st gen cooler leaks and I put on a 2nd gen cooler but now have no oil pressure, new oil change only took 4 qts. w/ new filter. always took 5 1/4 so I know something is wrong but what? I'm putting the old cooler back on after some work on it. in the meantime my daily driver is parked.

I want to use this cooler later on another car so i need to fix it. any ideas?

Thx. Rich

try cracking it over without letting the car start, and oil filter off. may have air in the oil system.
check oil again before starting

Oil cooler themal bypass valve may be shut as motor is cold so not allowing oil in, this may explain why its not taking as much oil as previously. (it should take more as the fc cooler is bigger).

Fill the cooler before you install/tighten down lines.

take the bypass out and clean it and make sure its working..