What t-stat and mods???????

 

Agreed, 210 is fine. I did a radiator flush and put a 180 Thermostat in, so it runs around 180-200 now.

 

what mods ^ mine fluctuates from 195 to 210 depending on driving conditions and weather

 

If you are concerned about the 210 and you should be because these engines should not be that hot. The only reason they are is because the cooling system is a piece of crap especially the single core radiator. Contact radiator barn and you can get a replacment 3 core for about 209 and the temp will run in a more comfortable range about 190 to 200 and should rise a little at idle in a drive thru.

 

Just out of curiousity, what sources gave you that info?

The Jeep 4.0 runs at a 'normal' 210. The engine was designed to run hot, thats why they built the block and heads the they did (up until the 2000 model head... which is why it is notorious for cracks). Even with a beefed up radiator, which I have in mine, the temp will only run to around 195-205. The thermostat monitors that. So, I just dont see how 190-200 is fine, but then 210 is bad.

If my XJ ran 210 all the time with a stock rad, I would be VERY grateful.

 

210 is normal.

 

....going by the factory gauge?

 

I would definitely verify the engine temp. Get a heat gun and point it at the t-stat housing while its running at that temp. Make sure your gauge is at least close. So you really know what is going on. Or you can get a ScanGaugeII or usea scanner to verify also.

 

What mods? Come on, tell us.

btw, mine runs at 210 also w/o any problems. My only issue is with the gauge that keeps jumping to 230 or 240 for a minute or 2 and then goes right back. Never seems to overheat.

 

i have a 99 and its been running at 210 for 11 months now, when i bought it, never had any problems with headgaskets or anything dont sweat it dude itll be fine

 

So, the factory gauge indicated 210 during the high ambient heat of this past summer and still indicates 210 now with substantially cooler ambient temps? Hummmm, what does that say about the factory gauge?

 

both my ECU and Gauge sensors read the same temps. year round i see between 205-210 at idle and around town, and around 200 on extended highway driving. and even out of curiosity i took a IR temp gauge and verified the temp

the time of year and ambient temp shouldnt make a difference in running temps once the motor is warmed up . the 50/50 coolant/water mix does its part in keeping overall temps stable

 

Sounds like you may have an air bubble circulating in there as well..

 

ECU and gauge.

x2

 

Please explain, for the dummy (me), what "ECU and Gauge sensors read the same" means.

In moderate/low ambient temps wouldn't coolant temps be right at the t-stat temp? If ambient temp is, let's say 40 degrees, why would coolant temp be 210, or is that just what the factory gauge indicates?

I can easily understand 200F at hwy speeds (factory t-stat), that's when there's both max air flow and coolant flow thru the rad.