SouthSeaPirate

So, twice on me now, my 01 has gotten a little warm on the highway; all the while runs as fine as it always does.
Today, and a week or so ago, this scenario happened;
Ran a little warmer than usual on highway (a little above 210), drove a couple of miles start and stop (basic in town driving), stopped at a store for about 10 or so minutes.
When I came out and started her up, she ran like a dead cyl (not that I can honestly know what a dead cyl feels like) or rather just rough. At this time, the temp is a quite a bit higher, almost at the next line after 210. This happens for about 5 to 10 seconds, rev it a couple of times. Temp drops to less than 210 and runs perfect again.
Other than this time, and exact same scenario, it always runs perfect.
Fan shroud is broken into three pieces and is barely held together by zip ties. However, today I was driving barely fast enough for first gear, midday heat, off and on for about an hour, with AC maxed, and elec fan not running (01s don't always run when AC on); without issue. So I'm thinking not the shroud.
Per previous owner; the water pump and rad (I think) was replaced. I just replaced the heater core.
No coolant loss.

I do have the 0331 head.

toasterknight

There was a problem with 01s where the fuel injector 3 would vaporize and cause an air bubble. If the engine was warm and you shut it off it is very possible that could be what happened. I believe the solution was a heat shield between the intake and fuel rail as well as wrapping the injectors in foil. Someone's may be able to clarify further though.

Firestorm500

That wouldn't cause hot temperatures.

Combustion gasses escaping into the coolant would, however.

toasterknight

I was thinking the high temps were causing the rough idle. It probably just needs cooling maintenance for the heat.

Firestorm500

Water pump, radiator, heater core already replaced. Current and previous owner have both been chasing cooling problems.

I guess you could get pre-detonation if the cylinder(s) get hot enough. Usually on '97 and up, if you go past where the owner says he is on the temp gauge, it will suddenly jump over as far as it can go to the right and scare the bejeezus out of you.

Running hot on the highway, but not around town, usually points to a cracked head, or a blown head gasket between cylinders. Unless it it blown into the cooling jacket, he won't consume coolant or boil the coolant quickly. There's plenty of airflow at highway speeds. Water pump and fan spinning pretty good too.

toasterknight

Its not a pre detonation problem with the 0331 vehicles its a lack of fuel due to it vaporizing in the fuel line.

As for the cooling system there are many other things it could be. Electric fan, fan clutch, thermostat, cracked head and many other things. We won't know until we get some feedback from OP.

SouthSeaPirate

To be clear, it is NOT overheating in any way shape or form. Do not confuse running hotter than normal as actually running hot. Also, other then these two instances, it runs perfect. And again, no coolant loss.
Yes, it does run warmer than I'm comfortable with and I'm hoping a Stant SuperStat and a non-broken to hell shroud will fix this.
After searching, and reading up on Cherokee heat soak and it's TSB, I can say the symptoms match this issue 100%.

Along with the fixes mentioned above, I will be buying and installing the heat shield recommended by the TSB.
Thanks for the assist all.

toasterknight

Your welcome. We all tend to take any increase in heat on 00-01 very seriously as they have the weaker head. There is something wrong with your cooling system because it is raising above 210 on the gauge its just not a larger enough issue that you need to be worried.