Use the search - this problem has been beat to death a number of times. The most likely cause is the temperature switch on the thermostat water box.... ground the wire to the switch and see if the O/D works. If it does, the switch is bad..... or the thermostat isn't letting the engine come up to operating temperature.

Frank

'89 [color:"white"]G-Raider[color:"white"] [color:"black"]Supercharged 3.0L, MegaSquirt 2, lockup A/T, 2.5" exhaust, 172k, Cibie H4s/Oscar SCs, Hella Micro DE fogs, Cobra CB, Superwinch hubs, LSD rear/Aussie Locker front, Bilsteins, Lifeline AGM, Rust-Oleum