Well, I think I diagnosed the issue with puking coolant.

We swapped the idiot lights with an instrument cluster with proper gauges along with the proper sensors. Easy job thanks to all the good "How To" threads on the forum. Once we drove it around with the new gauges, we noticed that the XJ quickly got up to around 230F in city driving while the weather was only around 60F. I noticed that when we shut off the XJ, the viscous fan continued to spin for about 5 seconds when hot. When cold, the fan spins more freely than I would expect, but it also seems to spin pretty freely when hot. Time for a new fan clutch.

I went ahead and got a 180F thermostat, too, but I intend to replace the fan clutch first to see if that is all it needs.

My question for you:
From a sticky here, it sounds like you can replace the fan clutch without removing the serpentine belt. Is that correct? Is that recommended?

 

No need to remove the belt. But the fan shroud does need to come out.

 

maybe as well put on a new belt while you are at it.

 

Thanks for confirming. That should make it a quick and easy job.

 

I will check it today when I start the job, but while the XJ only has 67K miles, it appears to have a very new belt already.

 

Your jeep looks great.

 

Thank you!

 

Good news / Bad news. The serpentine belt looked perfectly new, so we left it on when we replaced the fan clutch.

The good news is that the old one was obviously leaking and worn out. The new one stops immediately when the engine is shut off instead of running for 5 seconds like the old one.

The bad news is that the car still runs WAY HOT for my liking. Driving around the block in 68F weather resulted in the temp rising to just shy of the 235F(?) line on the gauge.

Thoughts on next steps?

 

High possibility that your water pump has lost it's ability to pump due to erosion. I would also suggest bypassing the heater control valve and performing a good reverse flush of the heater core. Also you need a 195 thermostat for the Jeep to run correctly...

Hope this helps...
Happy Thanksgiving

 

May as well put in the replacement thermostat. Even with a good thermostat the electric fan should be on at that indicated temperature. If it’s not, either the gauge is wrong, the fan/wiring is bad, or you have a bad coolant temp sensor.

Probably

 

If the thermostat doesn't have a bleed hole, add a 1/8" hole near the upper edge. That will help get the air bled out of the system.

 

Thank you, all. I read about 100 threads on 195F versus 180F thermostats on this forum and others, and while I see the validity on both sides, since we were already late getting out of town for Thanksgiving, I went with the 180F. I can easily switch it later if it becomes an issue.

That said, replacing the thermostat and flushing the system did the trick. We have driven about 700 miles since, a mixture of city and highway, and the gauge has never read more than about 205F. Most of the time it appears to be in the 195-200F range.

As for the potential impact to fuel economy, we averaged over 19mpg over the 700 miles, so it seems to be doing fine. Again, we will switch it back to a new 195F later if we have any problems.

I know you all like photos, so here is the XJ after all of our work to get it ready for the cross country trip. New 235/75R15 Cooper Discoverer AT3 tires (which I love so far), new window tint to hide what is in back, new fan clutch, thermostat, rear drums, instrument cluster, radio, security system.

 

I love a happy ending.