Originally Posted by Kahoona360

HI
Thanks for putting up with my questions. I just thought an update was in order here. I did most of what was suggested.

Added the injector covers on 3 and 4 to stop heat soak. They did not fit right bit they did stop the heat soak problem. Perfect.
Added a trans oil cooler. Put it on after the existing one for may effectiveness.
Used a cooling system cleaner and refilled with fresh antifreeze and distilled at a better than 50/50 rate.
Verified that the fan clutch was working. I do have the metal blades too.
Verified that the electric fan works. I did buy the kit to turn the fan on with a switch but havent put it in yet.
Radiator is already new.
Left the 0331 head on. Heard that if they make it to 120000 they would be OK besides I wond up with about 3 grand in 4wd mechanical stuff so I am broke.
Changed all fluids with the best I could find.

We have been in Death Valley going to all of the places we could not get to before. Yesterday it was 100f and we went up Echo Canyon from sea level to 3,000ft. It was loose sharp gravel most of the way with some fun twisty bits. I was surprised at how much clearance we seemed to have. No complaints from the trans, the engine just squeaked over 120 for a minute and came right down. We were using AC for most of the ride till the outdoor temps dropped with the altitude. Not a problem at all. I am very glad I asked here. Tomorrow we will move up to the northern end with more difficult roads. We named it the Big Horn Sheep because it is white, follows the RV around all of the time and has big horns.

Originally Posted by robsjeep

So from what I read here is the thing that finally reduced the coolant temperature was the chemical rust and scale treatment, correct?

Becareful with rich antifreeze mixtures. Richer antifreeze mixtures have reduced cooling capability, and if too rich the boiling point gets lower again. Stay within manufacturers recommendation.

I do death valley in my xj too, great place, some neato mines to explore too. Panamint is nice too. Great place to explore. Be very aware of driving over salt in that area. some trails do cross salty areas. Many places in that region have dirt made of dried saltwater ocean residue wash the jeep well when done.