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Overheating

3K views 32 replies 10 participants last post by  ashtonjarrett 
#1 ·
Hey everyone,

So it looks like I have an overheating issue. I'm currently hanging out on the side of the road waiting for my TJ to cool down for the second time. In the past week I've hit the red and had my coolant boiling to the point where I needed to pull over to cool down.

I went wheeling about 2 weeks ago. Ran her hard for hours on hours on a 60 degree day and no issues. She was even fine on the interstate the 3 hour drive home.

I thought it was maybe dirt and mud on the radiator so I rinsed the radiator good; although I feel like the heat issue would have happened right after wheeling and going home on the interstate.

I even drove her up to my local 4x4 shop for them to fix a repeat repair issue on my rear main seal; they shouldn't have touch anything relating to cooling.

The into common factors on the over heat days are that it's been in the mid 80's and I was running A/C; which I normally don't run.

I'm i correct in thinking this is abnormal?
 
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#2 ·
Could be a sticking thermostat which caused mine to intermittently overheat. Replacing it with a new 195 degree (factory specified temperature) thermostat fixed it. Make sure to avoid the so-called "fail safe" thermostats that tend to fail prematurely in the open position.
 
#3 ·
Good to know; any particular manufacturer you trust Jerry?

And I guess the only other piece of relevant information is that it also only seems to be the recycled air A/C setting that correlates the issue happening. Ran regular A/C; which seems to be a much lower power and less stressing application. Not sure if it's relevant or related
 
#12 ·
Good Luck with the flush. When I first got my TJ I changed all fluids and flushed and cleaned my radiator with Prestone cleaner/flush. Radiator started leaking from 3 different places in less than a minute from the time I started the engine after completion. I'm kinda glad it did while in the driveway and not off somewhere In the middle of the night.
 
#15 ·
I never drilled mine and they work fine. To each Is own. If you want to drill hey go for it. As far as burping/ bleeding park with the front end on a steep hill or jack it up. Cap open. Running. Add fluid. Gravity does the work. As much as I like a good squeeze. It's not needed.
 
#17 ·
A good burping takes about 30 minutes. The engine has to get up to temp to open up the thermostat and then it takes some time for the air to make it's way out depending where the air is stuck at. You also want to rev the engine to about 3k RPMs for about 10 seconds each to force some of the air out.
 
#21 ·
A good burping takes about 30 minutes. The engine has to get up to temp to open up the thermostat and then it takes some time for the air to make it's way out depending where the air is stuck at.
If you disconnect the heater hose from the thermostat housing, then fill the radiator until the housing nipple overflows, you can leave "burping" to the babies. You'll have to figure out what to do with the 30 minutes you save.
 
#18 ·
UPDATE:

Brought it to my local shop.

Radiators toast. They pulled out some fluid and that things a rust bucket internally; probably where my heater core issue came from last year. Radiator cap was also only holding about 4 PSI. Got a new cap for the meantime

So I need a new radiator. Buttttttt I need to flush out all the sediment and junk from the block. The gentleman at my local shop recommended I just pop a freeze plug or pipe plug, spray it out, agitate it with a hanger wire. Head gasket and block pressure all seem fine. Any one know of a good write up on washing out the bottom of the block?

I've got my new thermostat and gasket ready. I'll pick up a radiator tomorrow, maybe a good time to invest in a high performance radiator. And try and do the work tomorrow. Anyone have any input or suggestions?
 
#20 ·
For the radiator, OE Mopar which has an all aluminum single row core. There are too many shoddy aftermarket radiators, I don't trust them and I don't know of any "high performance" radiators worth installing. For what it's worth, my original OE Mopar radiator keeps my engine cool in the hottest desert conditions while rock crawling.

And rust in the coolant is a sign the coolant wasn't changed often enough. Be sure to only mix concentrated coolant with distilled water, NOT tap water. Zerex G-05 is an excellent and strongly recommended long-life HOAT coolant.
 
#19 ·
Plain old single core radiator will do you just fine. With all that crap that was in there and since you will have the coolant drained already, I'd take off the water pump and take a look at it as well. Ounce of prevention, right?
 
#24 ·
Prestone has a great flush kit. It's cheap. You splice it Ito your heater core hose. Flush with tap garden hose. And they have a flush additive. I recommend draining all that tap and add distilled water with the lowest concentration of antifreeze you can have. 50/50 30/70 depends on climate. Needed 70/30 in Ak. Water cools better. Antifreeze stops boil overs and freezing. It has additives that help with corrosion. They fade over time and it becomes corrosive which is why it needs to be changed. Pure water is not corrosive. :)
 
#30 ·
Back flushed the system with the prestone kit, replaced my radiator, thermostat and gasket and filled with coolant from the dealer. (For anyone reading for help in the future; the kit is nice but doesn't get the heater core that well. I flushed the heater core separately afterwards.)

Made it home to Seattle without moving from about 200-205. It was dark and cooler so we'll see how she holds up for longer drives in daytime heat now.

Only hiccup I had was my fan shroud bolts are too big for my new radiator. Zip ties worked for a temporary solution.

The hoses seem ok for now; didn't replace them because they are still soft and pliable and my bank account hates me after today as is. The hoses were a little gnarly inside but if took a pressure washer to the inside of each hose before installing the new parts.

Thanks for everyone's help; hopefully my cooling system is healthy now.
 
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