If you look at where your oil filter assby is...also where the cool lines hook up, you will see a rather large (the ones I have seen are brass) plug. If you' remove the plug there is a spring and diphram. These parts regulate the pressure and temp. Now mind you, this was on MOD trucks, but wouldn't think it would change much. Personally I removed the cooler and gutted the assby. I have run a 2.5 pretty hard ( VOT 13...4 people/RTT/all our gear) and never had pressure or temp issues.
Even with my "newer" motor running down the freeway for 10 hours there was never any issues.
Hope this gives some onsite.
06 L322 Range Rover "The Black Pearl"
06 L322 Range Rover "2.0"
97 Disco SD "Emma" (250k and going strong)
95 P38 "Gus" RIP
99 P38 Callaway Edition #106 RIP
85 Defender 110 2.5NA "Margret"
01 D2 SE7 "Cuzn It" (blown up POS)
03 D2 SE "Fred"
Hoarder of 2.5 NAD parts
"In God we trust. Everyone else keep their fucking hands where they can be seen."