I'd be worried before it reached 235 in normal driving conditions with the 4.0 engine.....If it reaches 217 and the auxiliary fan comes on and you're not pushing it, something is amiss with the cooling system. Don't want to push your luck as overheats are very hard on the engine, particularly the cylinder head.

 

Especially this time of year. In August, in West Texas, in triple digit ambient, in stop-n-go traffic......it won't run 210 where the factory gauge normally points.

 

whats a good ways to bleed the air out

 

My 87 runs around 175 which is slightly cold for my taste but im mew to jeeps. But my understanding is that 50/50 boils at 212 so.......my aftermarket gauge in my car has a red dash at 212 as well

 

Bleed air by letting motor idle with the rad/bottle cap OFF (depending on open/closed system) 'til t-stat opens and coolant is circulating well. Install a new rad/bottle cap.

With the proper pressure cap, boiling point should be +/-260F.

 

Really? Explain why then...

 

The engine was designed to run at210. At 160 it will stay in "warmup" mode.

 

If everything in the cooling system is functioning correctly, usually your heater won't work worth a damn, in cold weather, with a 160F t-stat. Not sure about OBD-I ('95 down), but according to the OBD-II ('96 up) FSM, a completed heat cycle is counted by the ECU when coolant reaches 160F (end of warm-up mode). Nowhere does it say the motor was designed to run 210.

 

What is "warmup" mode and any links to documents stating confirming this? Not calling you a lair or anything, I just like to have facts over opinions.

 

I have a '94 and the heater works a little to well (haha), no issues with idle, honestly, I have yet to see any difference besides it running cooler.

 

What are your ambient temps? If u have a good heater with a 160F t-stat, in cool/cold ambient temps, motor may be running a little warm for the ambient conditions. My past experience in other vehicles with a 160 t-stat in cold weather........makes for a sucky heater.

The t-stat, in a properly functioning cooling system, only controls minimum coolant temp. Ambient temp, cooling system condition and driving conditions effect max coolant temp.

 

If the truck is running at 160 and the computer is still in warm up mode its using more fuel which is called running rich and can cause horrible gas mileage

 

"Warm up mode" is actually called open loop. While the engine is warming up the fuel trim and timing are controlled by pre set parameters in the computer. When it gets warm enough it goes into closed loop. This is when the computer begins to rely on sensor input to control the fuel trim and timing.... Basically.

 

With OBD-II, when the heated O2 sensor(s) reach operating temp, the "loop" can close very quickly and well before coolant temp reaches 160, a completed coolant heat cycle. Some heated O2 sensors reach operating temp within seconds of start up.

Heaters suck a 160 coolant temp but modern motors runs good and efficient well before reaching 160.

http://www.picoauto.com/applications/lambda-sensor.html