ryrycars

Jeep has been running fine with hot heat always ran at or slightly under 210. Today i was on my way to work and it was -6 degrees out and my heat just wouldn't warm up glanced down at the temp gauge and it was over 210 and climbing. It quickly shot into the red and i shut it off and pulled over immediately. coolant leaked out from the the driver side front from what I would assume was boiling over of the radiator out of the cap. I assumed it was the thermostat. I got it towed home and pulled the thermostat to find no coolant or water in the head or upper hose. i water tested the thermostat and it was fine. I replaced my radiator, thermostat, water pump and clutch fan a couple months ago and flushed my system a couple weeks ago before the cold really came. My question is does anyone have an idea why this happened? possible air or ice pocket? theres a chance I could not have bleed all the air out of the system.

Larry's XJ

New name brand antifreeze?

djb383

Did u replace the rad cap?......a properly functioning rad cap is critical to your "open" cooling system. When the motor is COLD frequently check coolant level in both the rad and bottle. Rad MUST be full to the top, always. Bottle should be +/-1/3 full, motor COLD.

Larry's XJ

7 hrs latter, no answer

ryrycars

i apologize for the delayed response. I took your advice and picked up a different brand of antifreeze. Ill go back today and get a new radiator cap as I can't remember if I replaced it or not. Ill keep it updated. Takes me awhile to work on it in this cold as I don't have garage space but hopefully can get it fixed today.

djb383

Re-fill the cooling system very, very, very slowly......pausing numerous times to add coolant. Let the motor idle with the rad cap OFF 'til the top rad hose is really hot or coolant/air start to burp out of the rad. Keep the rad full while idling. Install the new rad cap and check coolant level motor COLD each and for several days. Rad should always be full to the top and bottle +/-1/3 full, motor COLD.

As long as the cooling system is full AND all cooling system components r functioning correctly, antifreeze has nothing to do with overheating. It'll run cool without antifreeze, as long as the cooling system is full and components r good.

Antifreeze simply provides freeze and corrosion protection.

Larry's XJ

Reason I mentioned the antifreeze, I knew someone that ha d bought some that froze at about 25*. Don't recall brand or if recycled af.

Symptoms sounded simular to a frozen radiator.

djb383

There's all kinds of hypotheticals, I suppose. I could see a frozen radiatior causing motor overheating but if the motor is overheating AND the cooling system is full, the heater should be really, really, really HOT.

Motor overheating and no/weak heater after a cooling system overhaul sounds like coolant level was very low due to improperly filling the cooling system (or a leak). U can't re-fill a cooling system too slowly.

ryrycars

Update: got it all back together and filled up let it run to operating tarp with cap open. Put cap back on and I have a leak somewhere from the filler neck on the rad. I've tried 3 different caps with no luck for that so now I'm trying to figure out where it could be leaking from.

ryrycars

At this point I am pretty sure my radiator is frozen or there is an ice block somewhere. While trying to work out the air bubbles, my radiator started pouring coolant well before the top hose ever got hot, in fact it never really got hot just warm. I believe there is some sort of blockage either in my engine or the radiator. Any thoughts?

Larry's XJ

If it is froze, a well heated garage might be only way to thaw out. 2nd would be garage with a torpedo heater blowing at it for good period. Last would be back flushing/spraying outside with hot water. Plugging inlet and filling as best as possible, let sit, drain, repeat.

It's supposed to be almost up to freezing here N of DEEtroit tomorrow, might be your best shot as I presume it might be hair warmer in Dayton

If the rad is clogged you might be sunk.

djb383

I'm confused .......the cooling system has had antifreeze in it all along, yes/no? If there's ice inside the motor, it will rapidly melt moments after the motor is started. There's no way the motor will overheat with ice inside it and vice versa, there's no way ice will remain inside a hot motor.

If the coolant level leaked/dropped below the t-stat level, then the heater core is receiving little to no coolant....no coolant to/thru the heater core, no heat in the cab.

If the antifreeze/coolant level is low in the radiator, say +/-1/2 air, +/-1/2 antifreeze/coolant, air will not freeze and antifreeze/coolant will not freeze.

Sounds like u need to find your receipt for that 2 month old rad and have it replaced under warranty and go from there.

micki

i have a 2000 4.0 and it has been overheating on idle for about a month. However it *did have some heat (not great, i had to keep the blower on very low or the next step up.) we replaced the water pump and the thermostat yesterday and it overheats sooner than it did before, so that i have to shut it off at stop lights, and there is absolutely NO heat now. it also had the radiator replaced on wednesday because my mechanic was letting it run & it blew out the radiator. however, after he replaced that, it was running the same as it had been (overheating when idling & *some heat.) anyone out there know what might be the issue?

djb383

Bad fan clutch, heater core plugged or blend door malfunction.

Hendur2@comcast.net

-make sure cooling fan runs..mine is now connected to the ignition switch. Plus, a tight fitting reservoir cap is key! Does your Defrost work on high heat? Check fuses as well. Worked on 3 friend's Jeeps.