All I'm saying is that if you run "overcool" (i.e., not reaching operating temperature) which never may be a problem in Cherokees, the engine management system may not go into closed loop even with heated oxygen sensors. I'll stick with a 195° thermostat and the rest of my well maintained stock cooling system and never overheat and get the same MPG as new after 14 years and 226,000+ miles.

 

Been running a 180F t-stat for 6 mos now....according to the ScanGauge, closed loop is reached in less than a minute after engine start-up and well below normal operating coolant temp. As soon as the upstream O2 reaches operating temp, the system enters closed loop and runs lean and clean.......at least that's the way OBD-II functions. There's no reason for the system to operate in open loop until normal coolant temp is reached when the O2 sensor (that determines rich/lean air/fuel mix) has reached operating temp within seconds of engine start-up.

 

idk about you guys but i got crapy mpgs when i had a stat in and i took mine out and its rund around 180-190 and it seems i get about 15 more mpgs, then again i i dumped a lot of money in to my motor as well upgreading it and all.

 

basically, if the thermo kicks in at 180, that's 10 degrees sooner than it would with a 190 (obviously!)...in effect NOT loading down your engine before it really needs it...the I6 can take the extra 10-20 degrees, but it also helps to upgrade the rest of the relative components (oil/water) so that they to will work more efficiently and effectively.

...down south, you don't want your thermo to kick in before 190-195, it's just not efficient for the thermo and the rest of your components that operate for that extra 10 degrees!

 

A properly functioning t-stat does only one thing.........and that is control the MINIMUM coolant temp, nothing else, zero, zip, nada.

 

What year?

192-195* is OEM. Spec operating temperature of the thing is 210-212*F.

1987-1990 can run a 180* without incident, if the thermostat is the source of your trouble (it likely is not. But, what are your symptoms? Maintenance history on the cooling system? You may not need a water pump, either...)

1991-1995 is iffy - it will run just fine with the 192-195* piece, but some have reported that the 180* will work without "throwing a code." Up to you.

1996-2001 is OBD-II, and will throw a code if you put in a 180* thermostat (don't even talk about a 160* in its presence!)

As you can see, we need more information to answer your question properly. You may have it in your profile, but it's really good etiquette to give it in the post asking the question - year, engine, what's changed from stock, symptoms, what you've done (maintenance and attempted repair,) and the like...

 

i have a 96 classic. inline 6. just swapped motor, only thing i have done is remove the stat, newer fan clutch, complete system coolant flush. so the only thing left pretty much is water pump

 

No codes on our '98 with 180F t-stat.....gets mid teens city mpg and low 20's hwy mpg.

 

Really? You're an exception, then.

Granted, I have never liked the idea of an engine that runs that hot - if you lose pressure in the cooling system, you'll start boiling off coolant right about immediately. Bad idea.

I've pulled mine down to about 185*, but I'm working with a RENIX - and it don't kvetch at me when I make changes (CA does, so I have to make sure they're not obvious. No trouble with the Air Police, but I could really clean things up if they'd get out of my hair...)