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Radiator Cap question

Ok thanks for the infor Ecomike and lloking forward to hearing how everything goes Vanimal. I would like to hear your results. It sounds like we are having siilar problems so it is nice to have some comparison to get the gears turning.

I got to messing around some more last night and started wondering about the egr valve I might mess with that some tonight it doesnt seems to do anything, thinking maybe I need to learn about that a little bit. Kinda random I guess.

Any Ideas on where I should plumb in a coolant temp sender? The factory location is a tiny hole, I didnt see anything else on the head that lloked easily accessible.
 
got it all back together. flushed the system, changed the thermostat, all new hoses, new rad cap, fresh coolant, mixed at about 50%. radiator and waterpump are less than a year old.
let it idle in the driveway for quite a while, temp gauge was a little over 210. thermometer said 165 at the hottest. didnt seem like the thermostat was open, by feeling the upper hose.
drove it around for about 5 miles, hitting redline at about every shift. flogged it pretty good. pullled in my driveway and checked the temps with the engine still running. temp gauge was almost up to the line between 210 and 260. thermometer said 175. seemed like the thermostat was opened a little, i felt some coolant in there when i squeezed the upper rad hose. electric fan still didnt go on, that whole time. The fan did come on for a couple seconds when i shut it off for a few minutes and started it again, but shut off immediately. This means the engine isnt getting to 218 when running. It's fairly warm out today, if this matters.
Not sure what to think of all this, but i am going to call it good for now. hope this helps someone. dont trust the gauge.
 
Vanimal said:
got it all back together. flushed the system, changed the thermostat, all new hoses, new rad cap, fresh coolant, mixed at about 50%. radiator and waterpump are less than a year old.
let it idle in the driveway for quite a while, temp gauge was a little over 210. thermometer said 165 at the hottest. didnt seem like the thermostat was open, by feeling the upper hose.
drove it around for about 5 miles, hitting redline at about every shift. flogged it pretty good. pullled in my driveway and checked the temps with the engine still running. temp gauge was almost up to the line between 210 and 260. thermometer said 175. seemed like the thermostat was opened a little, i felt some coolant in there when i squeezed the upper rad hose. electric fan still didnt go on, that whole time. The fan did come on for a couple seconds when i shut it off for a few minutes and started it again, but shut off immediately. This means the engine isnt getting to 218 when running. It's fairly warm out today, if this matters.
Not sure what to think of all this, but i am going to call it good for now. hope this helps someone. dont trust the gauge.
Click to expand...

What brand and temp t-stat did you install? What thermometer are you using, and how?
 
bigsky said:
Ok thanks for the infor Ecomike and lloking forward to hearing how everything goes Vanimal. I would like to hear your results. It sounds like we are having siilar problems so it is nice to have some comparison to get the gears turning.

I got to messing around some more last night and started wondering about the egr valve I might mess with that some tonight it doesnt seems to do anything, thinking maybe I need to learn about that a little bit. Kinda random I guess.

Any Ideas on where I should plumb in a coolant temp sender? The factory location is a tiny hole, I didnt see anything else on the head that lloked easily accessible.
Click to expand...

IIRC an EGR that is stuck open can cause overheating, but I have yet to hear of a 4.0 Jeep that had that overheating problem. What year is yours? Only the 87-90 had an EGR. 91-01 does not have an EGR. The newer T-stat housings on the 91-01 had a place for a temp sensor, but not sure if it is any bigger.
 
Ecomike said:
What brand and temp t-stat did you install? What thermometer are you using, and how?
Click to expand...
195deg, failsafe i think it is? got the more expensive one at autozone, for whatever that's worth.
i have a radio shack infrared thermometer and a lab grade thermometer i use for anodizing that is known to be correct. I checked the radio shack one to my good one and they both read the same, within a degree or two. i checked the radiator, the hoses, the thermostat housing, and several places along the head, including where the temp sensor is in the rear.
 
Vanimal said:
195deg, failsafe i think it is? got the more expensive one at autozone, for whatever that's worth.
i have a radio shack infrared thermometer and a lab grade thermometer i use for anodizing that is known to be correct. I checked the radio shack one to my good one and they both read the same, within a degree or two. i checked the radiator, the hoses, the thermostat housing, and several places along the head, including where the temp sensor is in the rear.
Click to expand...

Hey vanimal, those fail safe thermostats are no good. After a certain temp they just stay open.
 
Ecomike said:
IIRC an EGR that is stuck open can cause overheating, but I have yet to hear of a 4.0 Jeep that had that overheating problem. What year is yours? Only the 87-90 had an EGR. 91-01 does not have an EGR. The newer T-stat housings on the 91-01 had a place for a temp sensor, but not sure if it is any bigger.
Click to expand...

Mine seems to have an EGR, it is an 89. I need to look into this.
 
im all over all of these over heating threads right now.
my rig is pertty much fine, until ive been driving in 100* + weather through the valley for 2 hours, then hit the long hills up in the mtns after that long drive, then it starts to get hot.
 
blondejoncherokee said:
im all over all of these over heating threads right now.
my rig is pertty much fine, until ive been driving in 100* + weather through the valley for 2 hours, then hit the long hills up in the mtns after that long drive, then it starts to get hot.
Click to expand...


Well if you think about, a steep incline implies that the hot air under the hood, which has a natural tendency to rise, starts fighting to move in the wrong direction. Add to that the huge extra load on the engine, and torque converter slippage while climbing, which can be as much as a 50 to 100% increased HP load, the heat load on the cooling system goes into orbit. So if the entire cooling system is marginal on flat land, it will not do the job climbing hills....
 
Okay, last night I jacked the drivers side front of my jeep up as high as I could get it and took the cap off while it was running and wiggled and squeezed every hose I could and got a bunch of air out. I knew there was still air in there. I will report my results after work tonight and see if she is still running hot. Wish me luck.
 
bigsky said:
Okay, last night I jacked the drivers side front of my jeep up as high as I could get it and took the cap off while it was running and wiggled and squeezed every hose I could and got a bunch of air out. I knew there was still air in there. I will report my results after work tonight and see if she is still running hot. Wish me luck.
Click to expand...

CRAP! Is that right? I better do this too then dangit. Is there an official burping method for the cooling system? Thanks for the heads up.

I notice that my XJ does not Fill, then Drain back coolant from the Full Cold to Full Hot line, and back again like a usual system.
 
^^You and bigsky have different systems (assuming both are stock). With a properly functioning system, the '91 should self-bleed over the course of a couple of heat/cool cycles provided you fill it carefully to start with.

Someone will tell you for sure, but if you are getting no flow to and from the overflow bottle, I believe the problem is likely a non-sealing radiator cap.
 
Pelican said:
^^You and bigsky have different systems (assuming both are stock). With a properly functioning system, the '91 should self-bleed over the course of a couple of heat/cool cycles provided you fill it carefully to start with.

Someone will tell you for sure, but if you are getting no flow to and from the overflow bottle, I believe the problem is likely a non-sealing radiator cap.
Click to expand...


I have an open system just like a 91 and newer, I did the conversion.
 
So todays results after bleeding the system some more last night I am still running 230 on the big hill coming home.

I think tonight I am just going to pour some gas on this thing and burn it. This problem never seems to go away.
 
perhaps your water pump is the incorrect rotation. they have standard and reverse rotation pumps.
 
Well which one goes on what motor? And how the heck do I find out what I have and what I need?

I still have the reciept for the waterpump that I have installed, I will check the waterpump against Napa's website and see which one I have on there right now.
 
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