So i bought my XJ last september. As soon as i got it back to my house i did a coolant flush and replaced the thermostat kuz i noticed it was takin way to long for it to warm up. Its now just past the coldest point in our Canadian winter and the thermostat is starting to act up again. If i let the truck sit at idle for about 5 -10 mins, it'll warm up to its regualar temp. BUT, as soon as i get moving, the thermostat opens up and the temp drops to the second line on the guage.
THe thermostat i've got in it is the one that opens at the lowest temp (dont remember the number.. 196 maybe?). Anyone know whats goin on? or should i just replace my thermostat again?

Thanks alot.

Jesse J.

 

The thermostat will open at a certain temperature that it is designed to. Once it does, and the fluid starts circulating, the temperature of the fluid is going to go down. I live in Oregon, and it has been around 30F lately, and mine does the same thing. I don't think you really have a problem.

 

that is normal you aint got to worry.

 

Sounds pretty normal to me too.
I just got my XJ too and after flushing the coolant and installing a gauge cluster with full gauges, I noticed that my temp will get to about 230 (almost to the line above normal) before it opens, but when the thermostat does open, the temps shoots down to the right range. I plan to do a bit more work on it in an attempt to keep the temps lower than they can get as I've heard that my current temps may lead to overheating on the trails.

You should be fine.
s

 

IT shouldnt get that high unless you are sitting still and aint moving.

 

Wow. I have a 180* in my '98 and the needle never moves. If I shut the heat off it will get up to 210*, but it never gets hotter than that, and never gets colder than 180* (that's the line on the gauge right before 210* if you're wondering.). Now my '92 has a large temp fluctuation, and that's due to my water pump heading south (it drips out of the weep hole, so I'm constantly losing a bit of coolant under pressure, all the time), so when it starts sweeping between 160* and 220* I know it's time to add some more coolant and burp it.

I'd say throw a new thermo at it, it's like a 10 minute job, and then top off and burp. I mean, just cuz it was a new thermo, doesn't mean it will last forever. Could be like the old joke: It was probably built on a Friday or Monday.

 

ya i failed to mention in the beginning.. it drops to the line above the first mark on the gauge and stays there. so its acting like the thing is stuck open. but i'll give it a couple days and hopefully it'll start actin normal again.

thanks for all the input

Jesse J.

 

Take a small hammer and lightly tap on the housing when it's up to temp, sometimes that will get them to act a little more normal. If you have a soft face or dual-face hammer, you can whack it a little harder...

 

Put in a 180 degree T-stat. It is a happy medium between too hot in the summer and too cold in the winter.

 

I have a 192F thermostat, my temp gauge reads just below 100 when driving at highway speeds in our cold winter. I let it run about 2 mins, then drive at a moderate speed to let things warm up. [also the Jeep is plugged in for 2 hrs before i start it,it's on a timer] Hows your heat? if it's good, then things seem pretty normal. I am also switching to a 180F stat once spring comes around. I flushed mine system and changed stat when i got my Jeep.