884x4

alright, 88 xj 4x4 4.0 242tc auto tranny 262k on the jeep
this thing is driving me nuts
i live in texas and it got 104 the other day and i was in traffic, the temp got to 255...heres the weird part, its got brand new..
radiator
thermostat
water pump
upper/lower hoses
pressure tank with volvo high pressure cap
upgraded zj fan clutch
new 50/50 mix pre diluted coolant
electric fan wired to a switch(diddnt help)
what else is there possibly to replace?!?! ohh heres another important part,
moving over 20mph it runs at like 200
help me out please guys, i know theres so many threads on this topic but iv searched and searched and it seems like iv done everything everyone else has...
thanks guys!-adam

PNWjeeper

Has it been "burped"? Could also be a bad temp sensor giving a false reading. Also if it hasn't been burped an air bubble could be stuck there overheating the sensor. Best thing to do if you haven't already is verify temp with an IR thermometer.

884x4

yeah i thought about the ir reader(do they loan those at autozone?) and it has been burped with the pressure cap not the temp sensor.
i just thought if it wasnt overheating while driving but idleing it was, it wouldnt be because it wasnt burped correctly.
thanks for the info man! i hope its a false reading..

Bob98Classic

When your Jeep got to 255, did it boil over?

I do not remember what the 50/50 mix will climb to without boil over...

884x4

what do you mean by boil over? it wasn't spewing or leaking anywhere

Klroach92

let it idle and get "hot" very likely temp sensor they are a pos on these cherokees djb sent me over to trail tech they have digital gauges, i also very temp by pointing my IR gun at tstat housing, but... if it is actually getting hot, it will be boiling over in the resovoir open it up and take a look. no not the rad cap the resivoir dont scold your face! i drive alot in +100 temp i lifted rear of hood it dropped it down about 5 degrees id never get that hot but a little over 210 at stoplights etc..

Klroach92

autozone/advance around here at least have nothing battery opd, do you have a federated or napa? they usually do or buy one for 40$ and have it they come in hand

djb383

Need to verify the gauge reading. Is the belt driven fan shroud intact/in place?

884x4

i have a napa near me so ill check out the ir reading at the temp housing, thanks guys!
and ill check to see if its boiling as well
no the fan shroud is not in place(previous owner took it off) but i really boubt that would be the difference between 200 and 255
thanks for the help guys!

freegdr

Fan wired to switch rotating in correct direction ?

884x4

yeah it is, but i shouldnt have to rely on the electric fan to keep my engine from overheating right?

Demonoid369

Here's a thought, your in Texas, hot heat, why do you have 50/50 mix? Should be more like 70/30 or 80/20. The higher number being distillers water.

SoCalxJ4.0

Your electric fan, and fan shroud are both very important parts of your cooling system.

djb383

It can mean the difference between running normal temp and overheating, depending on the driving conditions. The engineers designed most, if not all, of the cooling system components for a reason don't u think? Without the shround, the MAIN cooling fan will not pull max air air thru the rad. Any air not pulled thru the rad is wasted, cools nothing. Where is 255 anyway?

Bob98Classic

That is what I meant by "boil over", that if you had coolant bubbling in the overflow bottle.
My temp gauge on my 97 was reading 210, but when I checked the temp with too cooking gauges, they read 195....
I pulled the thermostat out to flush my cooling system, my 97 runs about
140, on a 85 degree day, but shows about 160 on the dash temp gauge...