2013 Jeep Radiator “Burping” Gone Wrong 😳

[LHC30]

My 13 JKUR was starting to run hot recently when driving at highway speeds and would randomly cool down a bit. Crawling in 4 lo is not a problem even at Colorado altitudes. So I decide to replace the thermostat and burp the system.
I get the sealed funnel all set up and followed the internet instructions of letting it idle while watching for the air to evacuate. I even set the RF up about 4” to provide a high path for the air. All is well for about 15 to 20 minutes- the level in the Funnel raises a bit and falls but is always near the bottom and the temp gauge was right on, or just under, the normal mark.

well, I suppose the water got to the boil point and all hell broke loose when it boiled over
Other than starting over and running the engine for shorter periods letting it cool in between, does anyone have a good answer why this is happening and why it was not mentioned in any of the several instructional threads I reviewed?
thanks.

 

[Crazyhippy]

I have always had good luck using a vacuum filling deal. Pulls the entire cooling system into a vacuum (crushes hose flat, which is pretty cool to watch the first dozen times), and then introduces coolant. They aren't very $$$, and vatozone might even rent them.

 

[Kachina26]

I've never seen that method. I can't say for sure what you have going on there, but there's a much better way to fill radiators. I bought this kit off the tool truck probably over 20 years ago and it looks like Harbor Freight has them now. Works like a charm and never any air. https://www.harborfreight.com/cooli....html?_br_psugg_q=radiator+pressure+test+kits
Amazon has them too in various price ranges and qualities. https://www.amazon.com/coolant-vacuum-refill-kit/s?k=coolant+vacuum+refill+kit

 

[Kachina26]

I have always had good luck using a vacuum filling deal. Pulls the entire cooling system into a vacuum (crushes hose flat, which is pretty cool to watch the first dozen times), and then introduces coolant. They aren't very $$$, and vatozone might even rent them.

Beat me by 2 seconds. I wanted to make sure I had the links and the video. Our transmission guy was the first one in the shop to buy it. I ran on to the tool truck and said, "TAKE MY MONEY!". So easy and such a time saver when you're on flat rate. But also probably partially responsible for my tinnitus.

 

[77charger]

when I changed wife’s xterra radiator last month it was a pain to get the air pocket out too.

Found I had to fill it rev it heater on water would drop I refill. It kept bubbling forever too. Finally got it purged out.

 

[Sandlord]

Besides the funnel kit, you also need to open the cooling system bleed screw on the front of thee engine, drivers side.
I think it looks like this. (It’s been a while). Mine is a 2015

 

[SoCalDave]

Yep you gotta get an air evacuation tool. I used this one when I used to work on cars/trucks. It's since been passed down to Kevin as I didn't use it anymore.
There are cheaper versions out there that probably work just as well.

UView 550000 Airlift Cooling System Leak Checker and Airlock Purge Tool Kit https://a.co/d/gudiS37

 

[LHC30]

Besides the funnel kit, you also need to open the cooling system bleed screw on the front of thee engine, drivers side.
I think it looks like this. (It’s been a while). Mine is a 2015
View attachment 1410964

Yup, did that.

 

[Sandlord]

Yup, did that.

I left the funnel half full overnight and it was empty in the morning. 2 days in a row.
my temp gauge hits just below half.

 

[LHC30]

So to use these vacuum fillers, do you need to have no coolant in the system before starting?

 

[Kachina26]

So to use these vacuum fillers, do you need to have no coolant in the system before starting?

That’s the best way. You can collect your coolant in a clean container and transfer it to a 5 gallon bucket. I had a special bucket just for coolant when I was at the dealership.

 

[BingerFang]

Thanks for the laugh!

 

[Bigbore500r]

My 13 JKUR was starting to run hot recently when driving at highway speeds and would randomly cool down a bit. Crawling in 4 lo is not a problem even at Colorado altitudes. So I decide to replace the thermostat and burp the system.
I get the sealed funnel all set up and followed the internet instructions of letting it idle while watching for the air to evacuate. I even set the RF up about 4” to provide a high path for the air. All is well for about 15 to 20 minutes- the level in the Funnel raises a bit and falls but is always near the bottom and the temp gauge was right on, or just under, the normal mark.

well, I suppose the water got to the boil point and all hell broke loose when it boiled over
Other than starting over and running the engine for shorter periods letting it cool in between, does anyone have a good answer why this is happening and why it was not mentioned in any of the several instructional threads I reviewed?
thanks.

View attachment 1410958

I just went thru this bullshit with my wifes 2012 JKU......

I even used my vac-fill attachment to suck all air out of the system, put it under 22" of Vaccuum, and then refil. Same shit - was getting hot when running at higher RPM's, accellerating, freeway, etc.

Tried to burp it for hours, same process and filler attachment as yours. It would do the same thing - create a never-ending geyser, no matter how many times it was burped.

I ended up changing out the NEW thermostat (dealer supplied Motorad thermostat due to Chrysler's thermostat shortage . . .) with a genuine Mopar thermostat I was able to find online.....and the problem was eliminated. It burped the air bubble right away when refilled, and temps are rock solid now.

Not sure if you have a non-OEM (or old) thermostat in there, but if you can't burp it and its doing what your describing.....get an OEM MOPAR stat and swap it out.

Or - Just sell the Jeep, that's actually my first vote

 

[LHC30]

Thanks BB500, I just removed a Motorad that a local mechanic put in during some other work a few years ago. I replaced it with a new Dorman. I’ve heard only OEM works and I guess it’s true.

 

[Ziggy]

Maybe if you sling it over your shoulder and a couple swift pats on the back will help burp her.

 

[paradise]

I just went thru this bullshit with my wifes 2012 JKU......

I even used my vac-fill attachment to suck all air out of the system, put it under 22" of Vaccuum, and then refil. Same shit - was getting hot when running at higher RPM's, accellerating, freeway, etc.

Tried to burp it for hours, same process and filler attachment as yours. It would do the same thing - create a never-ending geyser, no matter how many times it was burped.

I ended up changing out the NEW thermostat (dealer supplied Motorad thermostat due to Chrysler's thermostat shortage . . .) with a genuine Mopar thermostat I was able to find online.....and the problem was eliminated. It burped the air bubble right away when refilled, and temps are rock solid now.

Not sure if you have a non-OEM (or old) thermostat in there, but if you can't burp it and its doing what your describing.....get an OEM MOPAR stat and swap it out.

Or - Just sell the Jeep, that's actually my first vote

Ironically just had a buddy have this exact same issue about a month ago. I’ve heard more about thermostats in the last 30 days vs the prior 5 years LOL

 

[LHC30]

Maybe if you sling it over your shoulder and a couple swift pats on the back will help burp her.

That’s what I use the boulders for! Lol

 

[LHC30]

Local dealer has them in stock. Headed there now

 

[rivermobster]

I just went thru this bullshit with my wifes 2012 JKU......

I even used my vac-fill attachment to suck all air out of the system, put it under 22" of Vaccuum, and then refil. Same shit - was getting hot when running at higher RPM's, accellerating, freeway, etc.

Tried to burp it for hours, same process and filler attachment as yours. It would do the same thing - create a never-ending geyser, no matter how many times it was burped.

I ended up changing out the NEW thermostat (dealer supplied Motorad thermostat due to Chrysler's thermostat shortage . . .) with a genuine Mopar thermostat I was able to find online.....and the problem was eliminated. It burped the air bubble right away when refilled, and temps are rock solid now.

Not sure if you have a non-OEM (or old) thermostat in there, but if you can't burp it and its doing what your describing.....get an OEM MOPAR stat and swap it out.

Or - Just sell the Jeep, that's actually my first vote

This was a question I would use on applicants when I was shop foreman.

Why is the vehicle temp normal around town, but overheats on the freeway?

If they didn't say "stuck open thermostat", I sent them to Down The Road Motors.

Next!

 

[paradise]

This was a question I would use on applicants when I was shop foreman.

Why is the vehicle temp normal around town, but overheats on the freeway?

If they didn't say "stuck open thermostat", I sent them to Down The Road Motors.

Next!

I’m not even a keyboard mechanic but I like learning stuff. What makes a stuck open thermostat cause an overheat on the highway?

 

[LHC30]

Well, on the way to the dealer, I ran the Jeep pretty hard and it behaved as it should! We’ll see how long this Dorman t-stat lives but I have a new Mopar ready to go.

 

[Bigbore500r]

This was a question I would use on applicants when I was shop foreman.

Why is the vehicle temp normal around town, but overheats on the freeway?

If they didn't say "stuck open thermostat", I sent them to Down The Road Motors.

Next!

It wasn't stuck open, they actually don't open far enough and the passage size is different VS the factory one.
Seems like they work for a few months then fail, lots of horror stories about aftermarket stats in the 3.6 Chrysler motor.....but that's all you can get the past few years, and they are on fucking backorder! Like the ABS computer.....and the redesigned cam followers.....and the ........

 

[Bigbore500r]

Well, on the way to the dealer, I ran the Jeep pretty hard and it behaved as it should! We’ll see how long this Dorman t-stat lives but I have a new Mopar ready to go.

I'd change it out, its gonna screw you at the most inopportune time!

 

[Bigbore500r]

I’m not even a keyboard mechanic but I like learning stuff. What makes a stuck open thermostat cause an overheat on the highway?

Some vehicles might do that, but i've never had it happen like that.
The THEORY is that when the thermostat is stuck open (or missing) the coolant moves too fast thru the engine and doesn't have enough time to absorb the heat before it carries it off to the radiator.

A more typical scenario is the thermostat gets stuck open and the engine either takes too long to get to operating temperature, or it runs too cold when outside temps are cool.

 

[rivermobster]

I’m not even a keyboard mechanic but I like learning stuff. What makes a stuck open thermostat cause an overheat on the highway?

Coolant flowing TOO fast through the radiator. Doesn't have enough time to disapate the heat.

It's the most Obvious answer, and that's what I was looking for when quizzing new kids.

I had about ten silly questions. Can't even remember what they are now!

Experienced techs would go...

Really dude?

 

[Bigbore500r]

Coolant flowing TOO fast through the radiator. Doesn't have enough time to disapate the heat.

It's the most Obvious answer, and that's what I was looking for when quizzing new kids.

I had about ten silly questions. Can't even remember what they are now!

Experienced techs would go...

Really dude?

You've actually had thermostats stick open ,causing overheating?

The theory of "the water is moving too fast thru the radiator to dissapate heat" would be possible if the flow was increased from having NO thermostat at all....but a thermostat that isn't closing still has the same size orriface as one that is working correctly with the stat in the open position......

I've personally never been able to recreate this, even removing a thermostat completely

 

[4Waters]

Coolant flowing TOO fast through the radiator. Doesn't have enough time to disapate the heat.

It's the most Obvious answer, and that's what I was looking for when quizzing new kids.

I had about ten silly questions. Can't even remember what they are now!

Experienced techs would go...

Really dude?

You've actually had thermostats stick open ,causing overheating?

The theory of "the water is moving too fast thru the radiator to dissapate heat" would be possible if the flow was increased from having NO thermostat at all....but a thermostat that isn't closing still has the same size orriface as one that is working correctly with the stat in the open position......

I've personally never been able to recreate this, even removing a thermostat completely

Model A's over heat pretty easy. They didn't have thermostats back then however you can get one now and they fit snug in the upper radiator hose. The issue is that the thermostat doesn't allow enough water to flow either, some guys gut the t-stat and others weld 3-4 washers together with a 3/4-1" hole and put that in the hose to slow the water down.

 

[rivermobster]

You've actually had thermostats stick open ,causing overheating?

The theory of "the water is moving too fast thru the radiator to dissapate heat" would be possible if the flow was increased from having NO thermostat at all....but a thermostat that isn't closing still has the same size orriface as one that is working correctly with the stat in the open position......

I've personally never been able to recreate this, even removing a thermostat completely

You have to remember...

I've worked for seven different manufacturers over the years.

I'd like to say, I've seen it all, but just about every day, some new problem would float my way.

So yeah, I've diagnosed and repaired that issue more than once over the years.

@4Waters

A lot of guys with flats will do that same trick, replace the t-stat with a washer, just to generate some heat in the engine.