88 wagoneer xj.. 180k, new radiator, newish water pump..

originally got it, ran warm, replaced rad, ran fine, started running warm again.

rev engine, cools down rapidly. when i idle or am driving sometimes will start to creep, again, rev engine it cools...

any thoughts?

 

Does it have a sealed coolant system (no radiator cap, coolant is fillled from the resevoir)? if so, you may not have enough coolant in the system. I had the same problem with mine, it would only take a gallon of coolant to start with but i would pinch off the return hose and close the cap. After about 10 minutes of running i could take the cap off and the level would drop. I continued this process until i got about 3.5 gallons in the system

 

when was the last time you replaced the thermostat?

 

when i replaced the radiator... 2-3k/ 1-2 months ago