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Hey, anybody's XJ engine temp act like this in colder weather?

B

Blaine B.

NAXJA Forum User
Location
Northwest Indiana
With the cold weather setting in, I've noticed something....

When driving the XJ, the temp will get up to or slightly below 210. Then it will decrease to around 60-70 degrees, and then gradually rise back up to slightly below 210. Keeps cycling back down and up again.....I'l guessing that the coolant is so cool in this colder weather, the thermostat opens a little and then keeps closing a little in a cycle......anybody ever notice that with their XJ?

I have a 95, FYI......thanks!
 
Thermostat is new as of three weeks ago when I replaced the thermostat housing.

Coolant is full. Filled with engine on and rad cap off, then topped off resivoir to full.

BTW, I meant halfway between 100 and 210. I dunno what I was calculating there.......lol.
 
Last edited:
Mine does that same thing. Happened after I flushed and changed everything. Last winter I just put a jacket in front of the grill to keep it alittle warmer. Helped somewhat.
 
Ok cool, glad it's normal. Just never noticed it before. Summer/fall 2006was the first time I flushed/changed out cooling components also......bought the jeep last September (2005).
 
I'm not saying it's normal, because it's not. I just haven't figured out why it does it all of a sudden. I even changed the thermostat again thinking the other one was bad out of the box.
 
My jeep does the same, engine gets cold when you start driving.

I'm going to try a Robert Shaw T stat next and switch out my Modine radiator for a CSF from Dirk.
 
much the same prob here,
my engine runs cool all the time. My read out is metric (or whatever we have up here in Canada... normal is 100 as yours is 210) but I never get more than half way to normal (1/4 of the gauge) Tonite I cut some tin to block off half my rad and will see tomorrow if it helps at all. My t-stat is new, pump is new and I pulled my a/c condensor from front of rad... so I guess thats why its cooler (more air flow) If this recent mod doesn't help I'll be getting a new t-stat as they are pretty cheap and easy to do.
 
Mine doe's the same with the new rad. Didn't do it last winter. JIM.
 
I have the same problem on my newly rebuilt 90'. It warms up and then when I go down the road the temp drops to 150* and throws the RENIX ECU back into "open loop" and is causing me all kinds of driveability issues. Since I know that the cooling system is not at fault(everything is new), I just put some cardboard in the front of the rad. and behind the grill. I did not cover the tranny cooler since I tow with this XJ.
 
I am thinking that you guys have thermostat problems. Either you guys have 160* stats or you stock 195* stats are sticking open which can happen from time to time. The temp rating is stamped on the bottom of the stat.

Some folks think its better to run around 150-170* for more power, which is partially true but at those temps the ecm may go back into open loop. Also, oil never heats up above 212* and moisture will build up and cause some milky issues. It will also cause OBDI vehicles to fail emissions because the engine isnt fully warmed and the excess hydrocarbons aren't burned off in the exhaust manifolds and catalytic convertors.
 
This is what was causing my cooling problem.

11DSCN1457-med.jpg
 
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