What is the turbo boost under a load ? if it is not getting enough boost a series 60 will warm up, and backpressure on the exhaust from the stupid muffler MCI used will heat one it takes so little buildup in the muffler they used, the fan should be on high at 210F buy you a hand held non contact tachometer from Amazon with the strips and check the speed when it is cool and when it is 210F that will tell you if the fan is on high or low a fairly decent tachometer in from Amazon is under 30 bucks. On mine when it 1st started it would start on high fan and cycle to low in a few seconds with the Lining fan clutch but you may have a different fan clutch
That will be tested next as we go through California - Desert Center in a couple of days at 114 deg. Pulling the Wrangler. Thanks all, Kind Regards Phil
Here you go Phil. Maybe this is what you need in your bus.