Hey guys... I've got an 88 4.0 auto with a "problem" maybe. No matter what I do the running temp will not break 180 degrees ferinhiet. Is this good or bad or no a big deal? I can floor it or idle it but it won't break 180. I know most 4.0's run around 210. I think it's good because I have never once over heated. My electric fan is wired to a switch I put in on my dash and even at running temp with the fan off it still won't break 180. Im thinking the previous owner took out my thermostat cuz there is rtv on my water inlet/outlet. Am I just being nit picky or would it be best to find a way to get my jeep to run hotter?

 

Put in a 195 degree thermostat, previous owner may have swapped in a 180. It's a simple 7 dollar fix

 

First thing you need to do is VERIFY. There can be some inaccuracy in both the sending unit, the gauge or even both of them.

Get an infrared point and shoot thermometer (widely available and inexpensive now) or stop by a shop and have them point their IR thermometer directly at the thermostat housing of a hot engine. That reading will get you close to your true coolant temperature reading.

Then you'll know. Good data = good decisions.

 

Well I already did a cluster swap for an 88 4.0 5speed cluster with a tach to go into my 88 4.0 aw4 and both of them say 170-180 so it's not the gauge but could be the sending unit or just a 180 thermostat. I'll try the ir temp gauge but I don't think imma swap the thermostats out if it's actually running this cool because I'm getting 22-24 Hwy and I don't want any overheating problems later on.

 

How long have u had your XJ? Did it run 170-180 last summer? Have u verified it has a t-stat in it? I can't imagine an XJ, with a properly functioning cooling system/sending unit/gauge, actually running 170-180 year round.

 

I have the same approximate temps on my '91. In the 2+ months I have had it it only reaches 210 while idling for a period of time. Although I have yet to check sensors or gauges I am happy with the temp situation provided it is not an issue. Oh yeah it has been low 90s here a couple days and same temps.

 

Do u know if your XJ has a t-stat installed and if it does what temp? The OP states "no matter what I do, the running temp will not break 180" and I just find that hard to believe, especially if he drove it last summer. If all components are functioning correctly and a 195 t-stat is in place, 170-180 is not right.

 

I have a 87 renix that only gets to 170-180 too only goes up in summer when i sit ata red light for too long.

That was with a new t-stat

 

What temp t-stat?

 

What ever came up in Autozones computer as OEM Replacement. I did not get that technical with it. It was at the same time that me water pump went out about 4 years ago. I have had no problems and don't expect too.

 

So.....that's most likely a 195 t-stat but the gauge usually displays 170-180, hummm?????? If it's displaying 15-25 degrees below the stat temp normally, u may be getting a false reading at prolonged idle as well.

 

I aint worried bout it

 

Me neither.....but the OP seemed to express some concerns thus the responses.

 

If it aint broke...

 

Mine ran at that temp as well. Turned out there was no t-stat.