Correct me if I'm wrong, but if I have a 195* t-stat in my 4.0 shouldn't the "normal" operating temp be 195*? I'm confused on why people say that 210 is normal. tried searching but after 20 posts on over heating, I gave up. Can someone explain to me without a doubt why 210 would be the normal temp in an xj with a 195* tstat when my 92 YJ stays at 195 no matter how hot it is outside. My 95 xj on the other hand creeps up past 210 in traffic, but goes down to what ever the line is left of 210 on the freeway.

 

195 just controls when it opens. motors go to where there like. jeeps like 200-210. and the cooling systems are small and poopie.

if you put in a 160 degree you would actually run hotter than 210 because the coolant would not sit in radiator long enough to get cool.

measure your buddys yj radiator and then measure yours. see a difference?

 

its fine 195 to 210 is normal operating temp

 

You should be happy, at least you dont have to run your heater in the summer to keep it away from the redline. And thats with a new radiator, temp sending unit andwater pump. Count your blessings.

 

So you're trying to tell me that just because an XJ has a smaller rad than my YJ, it likes a higher temp? It's the same engine. Why would it "like" a higher temp? I understand that the smaller rad isn't as efficient, but a 4.0 is a 4.0, shouldn't they all run at 195? Seems to me, that logically, anything higher than what your t-stat is set for would be "over heating". Maybe not to the point of damaging the engine, but still hotter than it should be running don't you think?

 

my jeep has always ran 210. my cj ran 180 i belive and that was a 4.2l

 

Well, that's just my question. Just because someone's jeep runs 210 consistantly, doesn't mean that's what it's meant to run at. My question is, why would the normal op temp of an xj 4.0 be 210 when a yj's 4.0 which is the same engine is meant to run 195?

 

As already stated, 195 is the temp that the tstat opens for coolant flow. It's not that the 4.0 in the XJ likes to run at 210, it is just the normal operating temp that could be attributed to many factors. I know it does not make any sense and I can not offer any technical specs but it is the normal temp range.

 

Ok, it seems to me that the XJ cooling system is just inadequate to cool a 4.0 correctly. So here's my next question, what modifications have you guys made that corrected the problem and was able to keep the engine running at 195 in the heat of summer with the AC blasting? Flowkooler water pump? Alum rad? Anyone out there actually running 195* or is everyone just ok with their Xj's running warm?

 

It could be the limited size of the radiator, the inadequate airflow under the hood, or whatever else you can find that is different from a YJ. The norm is the norm on a XJ and we can question it until we are blue in the face but it won't change the temps. I replaced everything thing in my cooling system, water pump, hoses, heater valve, tstat, head gasket, and upgraded to a 3 row radiator and shes still runs a consistent 210.

 

X2 on that,I just did the same thing.

 

Anyone put a high flow water pump and/or an aluminum rad in? what was your result? What about venting the hood?

 

Hey I'm no expert but I did a bunch to my cooling system (3 row radiator, electric fan, system flush, etc) and it was still overheating almost to the red when under stress. So I replace the stock 195 thermostat with a 180 and now the highest I've seen it go is 210 when loaded down and going up a long steep hill. Under normal summer conditions driving in town and running the A/C it sits at around 190 to 200.

When you aren't running the A/C or anything it sometimes runs as cold as 160-170. Does anyone know if it is bad for the engine to run this cold?

 

Oh yeah, I have the Le Baron hood vents also. All they do is decrease the underhood temps and do very little, if anything for the engine temps. After reading about the Flowkooler pumps I decided against it when I replaced all of my parts. Mainly because of their claim that it increases waterflow at lower engine RPMs and returns to normal flow at driving speeds. The effective RPM range that was specified was outside my Jeeps normal idle RPM range and seemed to be a waste of money for minimum benefits.

 

I have hood vents and think they're great, but they don't do too much for engine temperature. they are more for under hood temperature which is also important for keeping other parts cool such as electrical stuff. When you hold your hand over the vents after a driving for a while you can feel the heat pooring out, so you know they work.