I'm about to help a friend of mine replace his radiator, hoses and thermostat. While researching, I noticed most recommend sticking with the OEM temp thermostat. I came across this online article about upgrading the cooling system on an XJ: http://www.4wdandsportutility.com/te.../photo_11.html

It suggests going with a 180 degree thermostat for improved fuel economy, and a 160 degree for performance. Anyone have opinions on this? Any downside to going with a lower one?

 

210(approx) is peak performance for a jeep. In terms of fuel mileage, etc.

 

Thanks for the good advice. Looks like We will stick with the OEM temp stat.

 

FWIW, I prefer a 180 and that's what's been in since January (bought the XJ early December). Get mid-teens city mpg and low 20s hwy, heater is excellent. Chrysler/Jeep does offer a 180 as an alternative to the 195. The 4.0L will run right at the t-stat cool/cold ambient temps and well north of the t-stat in hot ambient temps, according to the ScanGauge.

 

It may run hot with a 160. It is open so much to coolant just flows in a big circle and never stops in the radiator to cool off. I ran a 160 in mine for 1 weekend and it ran hot all weeekend. i put the 195 back in, now it cools around 220

 

That doesnt sound bad. Anyone else running a 180 degree thermostat?

 

When wide open, a 160, 180 and 195 all open the same amount and flow the same amount of water when wide open. When wide open, flow is determined by the water pump. At 220 a 195 is wide open. Here's a pic of a 180 wide open at 195 & closed at 180.

 

I was thinking of running a 180 in the summer and a 195 all winter, just for kicks.

 

My thermostat needs to be replaced. It must have broke, as its causing blockage and making the fill tank overheat and in turn causing the engine to run super hot, near 240 or so. I also need to flush the system, as my anti freeze, the very very little thats left, is completely dark brown.

 

Suggestion on a new thermostar: Stant SuperStat. Hands down best one avaiable. $2 more than the crap they sell.

 

There 2 reasons they made the jeep run at 210

1) the tolerances are machined to take into account thermal expansion

2) run too cold and the oil doesn't reach optimal temps for viscosity

These are the same reasons you should let your motor warm up when its cold out. But either way the 4.0 will still probably run forever for you as long as you change the oil, not overheat or hydrolock it

 

Ding ding ding

Ive been waiting for someone to say it this whole thread.

 

.....and the quickest way to get it up to normal operating temp is to drive it, not let it sit idling, wasting gas. I still say it won't run 210 this time of year.