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Weird cooling problem

C

chickenbot

NAXJA Forum User
Location
frisco
93 4.0 ax15 np231 3.07 stock tire size

So this past Sunday I flushed my cooling system and back flushed my heater core. Then I replaced my water pump, timing chain and radiator. I filled the cooling system back with 50/50 green stuff and burned the system. I don't have any cooling fans on the Jeep yet till I have my new fan controller. I also do t sit in stop and go driving going to and from work.. just a straight 30 min 80mph drive everyday. Well since I have replaced everything, while I am driving from start to finish, the temp just slowly rises to 230 when I shut it off when I get home. It is 67degrees out and driving 80. With the old equipment the temp wouldn't go over 130 and now with the new it's 100 degrees more. Btw I am not running a thermostat ATM until I get the new fan controller. I am stumped and do t know what to do. Any suggestions?

Old radiator - cheap Chinese eBay all aluminum
New radiator - mishimoto r2340 rhd 2 Core
Water pump - OEM Jeep
Timing chain - double roller Jeep racing
 
I would start by installing cooling fans. Those are kind of essential.


If you had fans and the same symptoms I would say it sounds like you may have air in the system.


If you think you have air in the system, try disconnecting the upper radiator hose at the thermostat housing. If there is no air in the system you should lose a bit of coolant, but if there is air you may not lose any. With that upper hose disconnected add coolant to the radiator until you reach the rim of the hose fitting on the T-stat housing. Reconnect the hose and then add coolant while burping the system by squeezing that upper hose. Once you can't burp it any further cap the radiator, bring the overflow bottle up to the correct fill level and see if your temps don't behave better.
 
Thermostats are a good idea too!
 
I agree.

Coolant is circulating to fast to dissipate heat through the radiator. The thermostats job is to hold coolant in the radiator lett it dissipate the heat then send it back to the motor to absorb more heat.

I'd also get some kinda fans on before summer heat gets here. My truck can get away with out fans but I highly doubt an xj can ounce Temps get above 80 or so.

Sent from my SM-G960U using Tapatalk
 
I have fans just no controller. I ordered the Trinity fan controller.. just waiting on it to get here.. kinda been waiting since October lol
 
Running no thermostat is an awesome way to crack a head. The water is moving too fast to absorb much heat from the metal; also the back cylinders will get superheated while the front cylinders are over cooled. Even race cars use a coolant restriction plate in place of the thermostat.
 
Evan03 said:
I The thermostats job is to hold coolant in the radiator lett it dissipate the heat then send it back to the motor to absorb more heat.
Click to expand...

You got that backwards!
 
The t-stat doesn't give a damn about the cooling system!
 
If you gave some good info on why and it comes out that im wrong ill be the first to say I was wrong you are right rcp.

For now the tstat does care and is a very important part of keeping a vehichle running at optimum temp. Without it vehicles can over heat and some run to cool.

Sent from my SM-G960U using Tapatalk
 
If you were running 130F, then I'd suspect that you T-Stat was bad. What T-Stat did you use to replace it? 230F is a bit high. Mine runs about 208F.
Edit, OK I see as other post have said, no T-Stat. I'd put a Super Stant one in. 195-197F. I have a MotorRad in mine presently. The Mr. Gasket fell apart.
 
Last edited:
A t-stat will go back in when the fans go in.. I am trying to run cooler temperatures so when I stop for half a second with no fans, it doesn't over heat. I'd rather the temp start rising from 120-140 when I don't have enough airflow over the radiator then the starting point being 210. Gives me a little buffer to get moving again and less of a chance to over heat. This is not permeant, just a band aid till I get my fan controller. Like I said. I have been waiting since Oct trying to get one.
 
Your xj has a fan controller built in the computer, it will send power to the fan relay at somewhere around 230 degrees. Use it and a switch until your fancy one come in. And put a thermostat in it! I'm surprised you haven't cracked a head or blew the head gasket already! A 350 chevy would have.
 
Well I don't have my original electric fan and the mechanical fan. I haven't had them for a few years now. Don't know why the head hasn't cracked or warped or blown a head gasket. She runs great just hot.
 
Just hook up the factory wiring to the aftermarket fan. Although looking at your year that won't work until you put in a thermostat. See, in your year, like mine, the sensor for the gauge is in the back of the head, (where you are not getting water circulation because you have no thermostat, ) do its reading hot. The temperature sensor for the computer is in the thermostat housing which is probably reading cold, due to excessive water circulation because it's right next to the pump and upper hose outlet, never getting out of warm up mode and it would never read an over temp condition to turn on the fan.

BTW, why did you buy a rhd radiator? I drive a rhd and use a lhd radiator.
 
So riddle me this.. when I drive to work in the morning, the temp will not go over 160.. the temp outside when I am driving to work is 65 degrees.. when I drive home in the evening, the temp will hit around 230.. the temp outside is 75 degrees.. everything is still the same as before. I drive the same speed going both ways.
 
chickenbot said:
So riddle me this.. when I drive to work in the morning, the temp will not go over 160.. the temp outside when I am driving to work is 65 degrees.. when I drive home in the evening, the temp will hit around 230.. the temp outside is 75 degrees.. everything is still the same as before. I drive the same speed going both ways.
Click to expand...

How long is the drive?
 
chickenbot said:
So riddle me this.. when I drive to work in the morning, the temp will not go over 160.. the temp outside when I am driving to work is 65 degrees.. when I drive home in the evening, the temp will hit around 230.. the temp outside is 75 degrees.. everything is still the same as before. I drive the same speed going both ways.
Click to expand...

Assuming the cooling system is topped off, its most likely that the thermostat is sticking or only partially functioning.
 
maxbraketorque said:
Assuming the cooling system is topped off, its most likely that the thermostat is sticking or only partially functioning.
Click to expand...

I believe he said he doesn't have one... which would explain it. Overcooling in the morning when its cold.

The temp on the way back is probably due to the lack of fans.
 
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