[zjlockers]

Opinion on temperature needle moving from middle to half-way to red-zone.
1997 Jeep Grand Cherokee, 'Limited', V8, 5.2liter, 4wd.

Sitting in 102F ambient temperature in the sun. AC on full-blast.
The temperature needle moved from middle to half-way to red-zone. When
I saw this, I "rescued" the jeep by moving it to a shady spot and then driving
it around to increase air flow.

Any thoughts?

(For possible extra clarity, the position of the needle was half-way between the correct
location and the red-zone.)

 

[Off Grid Access]

My 95 with a V8 does that as well when sitting on pavement in 100+ degree weather. I have never seen it go above that point though. Most of the time it runs a little cold, but in that specific circumstance it does get a bit warm. The other day I was driving my 98 (V8 as well) and my girlfriend was behind me in the 95. We were stopped for road construction on hot pavement and it was over 100 degrees out. The 98 never went above half way on the gauge while the 95 did exactly as yours. As soon as we started moving again, the 95 cooled right down. The only difference between the 95 and the 98 that I can think of was that the 95 is a lot closer to the ground since the 98 has a six inch lift.

 

[jeepjeepster]

This topic comes up on every ZJ forum/platform this time of the year. It seems that the 5.2 ZJ struggles a bit with removing heat at idle... It makes sense that the 5.9 has active air louvers and an electric fan....

There are a lot of things that can cause this, and I imagine this didn't happen when the Jeep was new. If the radiator is new and the cooling system is clean (not partially clogged up with whatever), then that leaves the clutch and fan. If the clutch is weak at all, this is when the issue would show up. Hayden does make a severe duty clutch that engages sooner and stays engaged longer. I've already installed it on my 5.2, but I've not gotten a chance to drive it in 90F+ heat with the A/C on, and most likely wont get to this year. Another common mod is to install a Jeep Liberty HD fan. Its plastic and evidently is more efficient than the stock metal fan. I've already bought one (52079654AE ) but may never install it, I just like having parts take up room. Summit and rock auto were the cheapest when I ordered it. Summit was cheaper since it has free shipping, but I was ordering other stuff from rockauto and the shipping didnt increase when I added the fan blades.

If the cooling system isn't in tip top shape, then that could also cause it even with a properly functioning fan clutch.

 

[LouC]

We have a 4.0 so there’s more room around the engine for air flow but what I found chasing the same problem….
Changed rad & water pump=same
Changed fan clutch to HD unit=same
Changed thermostat=solved problem the old one was not opening far enough!
Ours would go about one notch past the middle
Now it’s right at 210 no matter how hot it gets…

 

[LouC]

I actually tested the 'stats in a pot of boiling water with an old style radiator thermometer
what I found was that the original 19 year old stat, opened slower and didn't open all the way.
that's after changing the original rad (leaking) water pump (actually was fine) and fan clutch (probably fine too)
lesson learned check the 'stat FIRST. Now it runs at the mid point (210) or slightly cooler.