Help needed: Jeep suddenly overheating after changing the thermostat

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dukesilver24

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So basically, about a week ago, my coolant was leaking. I took it to the mechanic and had it diagnosed and pumped, where they saw the issue was the thermostat being faulty and was leaking quite a lot. I ended up getting the part and changing it and I also drained the remaining coolant in the radiator. I filled the radiator as well as the resevoir but I'm not quite sure if I did the process correctly since it started overheating when I tried to drive it around. I'll explain what I did so you guys can point out what I did wrong.

1. Putting components back together
2. Filled the radiator with the coolant along with the resevoir
3. Turned on the vehicle and left the radiator cap open then let it run for a few mins,
4. Drove it around the neighbourhood

Once I started driving it around was when the overheating started to happen and the radiator fan sounded like a plane engine. I immediately went home and turned it off. This only seemed to happen when I drove it around. I never had this issue before so I assume I'm probably missing a step. Kindly let me know.
 
Usually you have to raise the front of the jeep up some and let it idle to get the air out.

If you didn't use the proper coolant and added the wrong coolant to what's already in there it will solidify and not flow.

When the radiator is cool open the cap and check the coolant.
 
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BLACKJKU said:
Usually you have to raise the front of the jeep up some and let it idle to get the air out.

If you didn't use the proper coolant and added the wrong coolant to what's already in there it will solidify and not flow.

When the radiator is cool open the cap and check the coolant.
Click to expand...
I got the mopar coolant, my jeep is 2016 and I dont think there was a coolant change from the previous owner.
 
I replaced the Thermostat in mine last summer. What it starting doing intermittently after stat change .
Would heat up past the half way point for about 30 seconds than cool back down to half way point and be totally fine . Watched this for about a month than purcshaed another Stat.
Problem solved . New stat was sticking so faulty. Maybe that's what you have run into .
Def try new stat.
It's a good idea to have Jeep on a bit of incline when adding a lot of coolent . As I
guess Jeeps are a bit prone to air in the system . Haven't had an issue like that yet . Touch wood.
Sometimes Jeeps cooling systems can be finicky .
Let us know how you were able resolve the problem when you get it fig out
 
Typically, if there is air in the system, the temp gauge will move quite a bit, seemingly bouncing from hot to normal and back again.
As BLACKJKU said, you should let it cool, take the rad cap off and check coolant levels again. Fill the radiator with the front end elevated. What will happen is, you'll pour some in and the rad will bubble and burp. Let the coolant settle and repeat. Putting the coolant in this way forces the air out, but it's only way out is the cap, hence, waiting between pours to let the air out.
 
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If you used the right coolant, then my guess is air in the system. Jack up the front passenger and get a large funnel or a proper burp kit with excess fluid, heat it up squeeze the hoses with gloves, run the heat on high once at temp, use the bleeder valve on the thermostat housing, the whole nine yards. If that doesn’t work and it didn’t over heat before then you might have just gotten a bum thermostat. It happens sometimes.
 
Jermbob28 said:
If you used the right coolant, then my guess is air in the system. Jack up the front passenger and get a large funnel or a proper burp kit with excess fluid, heat it up squeeze the hoses with gloves, run the heat on high once at temp, use the bleeder valve on the thermostat housing, the whole nine yards. If that doesn’t work and it didn’t over heat before then you might have just gotten a bum thermostat. It happens sometimes.
Click to expand...
or the thermostat is in backwards.
 
Start your engine with the hood open and, if you have JScan, dial up the water temp PID and put your hand around the upper radiator hose. It should remain cool until the temp reaches about 200-210 or so, and you'll feel the coolant begin flowing through the upper hose. Don't hold on too long- it'll burn your hand in a minute.

If you start your engine when it's cold and you can feel water flowing through the upper hose immediately, you have a stuck open t-stat and your engine temp will hover just below operating temp and you'll get a P0128 code.

If you don't feel the water flowing through the upper hose until sometime way north of 220, either the t-stat or the temp sensor is bad.
 
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2015 JK, Unlimited Rubicon. Got 0128 code(low coolant temp) and replaced thermo with "MotoRad" brand unit, claims OE supplier. Under any kind of load, pulling a grade 3-4000 rpm engine got hot, warning light came on and hand to back out of the throttle, living in the AZ, CA, NV area this was not acceptable with summer coming on, re-installed factory thermo for now and its stays at the 1/2 way mark.
 
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JUST TO BE CLEAR ON REMOVING THE AIR I'M THE SYSTEM

YOU DON'T LET IT WARM UP A COUPLE MINUTES, YOU LET IT WARM UP TILL HOT AND YOU SEE THE COOLANT ACTUALLY FLOWING THRU THE RADIATOR, YOU WATCH ITS LEVEL IT SHOULD DROP AS AIR ESCAPES
( WEAR EYE PROTECTION 👆👆👆)
NOW TURN ON HEATER TEMP TO HOT FAN TO FULL

AFTER COOLANT IS FLOWING ADD COOLANT TO FILL THE LEVEL NEAR FULL... THEN APPLY CAP.. ( GLOVES MUST BE USED IT WILL GET HOT INSTANTLY)

PUT CAP IN QUICKLY.. LET RUN 5 MINS
SHUT OFF.

ALL DONE
LET IT COOL DOWN OVERNIGHT
START IN MORNING
IT SHOULD WARM UP CORRECTLY AND HEAT WORKS

IF GOOD SHUT OFF HEAT AND YOUR ALL DONE

CHECK FOR LEAKS


IF NONE.. GOOD JOB

IF PROBLEMS PERSIST YOUR THERMOSTAT IS CRAP, REPLACE IT AGAIN
 
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Wifes Rubicon said:
2015 JK, Unlimited Rubicon. Got 0128 code(low coolant temp) and replaced thermo with "MotoRad" brand unit, claims OE supplier. Under any kind of load, pulling a grade 3-4000 rpm engine got hot, warning light came on and hand to back out of the throttle, living in the AZ, CA, NV area this was not acceptable with summer coming on, re-installed factory thermo for now and its stays at the 1/2 way mark.
Click to expand...
Were you able to figure it out with the Mopar OEM stat? My son has a 15’ Rubicon. We’ve changed the radiator, thermostat (MotoRad from dealer since Mopar stat is on backorder), coolant temp sensor, and radiator cap. It was fine for a few days and then started overheating again. The stat has been changes three times in the past 6 weeks. This is driving me crazy.
 
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