2015 Jeep Wrangler Overheating Issue

[Anybodyhome]

But did the cooolant ever erupt back up out the radiator? Special funnel or not, why did the fluid rapidly rise with engine idling for me?

That's why I'd be concerned with some radiator blockage.

So I've put about 250 miles on it since I attempted to burp the system last night, covering all sorts of terrain and grades, including some light offroading (this is my job). Mostly stayed around the 210-222 range. Towards end of the day today it began the weird extreme fluctuations - would be at normal op temp and then spike to 228 and inch up in the 230s, then drop back down to 226 or whatever. Or running for a minute around 228 and then spike to 248 (that only happened once) and drop to 235. But mostly.....mostly it ran as expected today.

The temp fluctuation is not normal. Your temp gauge should remain pretty much on center regardless of driving conditions. This symptom, alone, leads me to believe the system still has air in it, albeit maybe not as much as before.

And again, when you start it cold, wrap your hand around the upper hose and you'll feel if you're getting water flow immediately. If so, the t-stat is stuck open and needs to be replaced.

The temp spikes are caused when coolant is not flowing through the water jacket in the engine block, even for a mere second or 2 and/or there is no air flow past the radiator. Did the temp spikes occur when moving and what happened when you came to a stop with the engine running? I'm guessing the temp may have gone up while waiting at a light or stop sign.

 

[NineLives]

Swapped my headlights out the other day and here are pics of my rad. Are these fins concerning to anyone?

 

[NineLives]

That's why I'd be concerned with some radiator blockage.


The temp fluctuation is not normal. Your temp gauge should remain pretty much on center regardless of driving conditions. This symptom, alone, leads me to believe the system still has air in it, albeit maybe not as much as before.

And again, when you start it cold, wrap your hand around the upper hose and you'll feel if you're getting water flow immediately. If so, the t-stat is stuck open and needs to be replaced.

The temp spikes are caused when coolant is not flowing through the water jacket in the engine block, even for a mere second or 2 and/or there is no air flow past the radiator. Did the temp spikes occur when moving and what happened when you came to a stop with the engine running? I'm guessing the temp may have gone up while waiting at a light or stop sign.

The spikes happen when moving/ at speed. Coming to a stop for traffic, it might inch slowly upward and then comes back down. These extreme changes only occur while moving.


About to head out to get another jug and do this burping again. I posted pics of my rad fins, if your have any opinion on that.

 

[Anybodyhome]

About to head out to get another jug and do this burping again. I posted pics of my rad fins, if your have any opinion on that.

Fins generally don't tell you anything unless you see rusting/corrosion/coolant residue around the bottom where there may be a leak.

When you burp again, really try to get the front end at least 6-8" above the rear end on a sharp angle. And don't use your specialty funnel, just use a standard funnel. You might have to pick it up off the radiator cap lip a little to allow the funnel to drain, so just go slowly. When you get a burp, let the coolant settle a little and add a little more.

Also, check the upper hose for flow when you cold start the engine, as I mentioned earlier. The upper hose should not start flowing until around 200-205, depending on the thermostat, and then it should warm up rather quickly, so don't hold on for long.

Do you have the JScan app with an OBD II reader? Think I asked before, but don't remember.

 

[NineLives]

Also, check the upper hose for flow when you cold start the engine, as I mentioned earlier. The upper hose should not start flowing until around 200-205, depending on the thermostat, and then it should warm up rather quickly, so don't hold on for long.

Cold start:

Heater core hoses hot to touch around 140-150.


Lower hose hot to touch around the 200+ mark.


Upper hose never got hot, as coolant bubbling up the rad neck and spilling over a bit. I shut off car at 213 degrees.

 

[Anybodyhome]

Cold start:

Heater core hoses hot to touch around 140-150.


Lower hose hot to touch around the 200+ mark.


Upper hose never got hot, as coolant bubbling up the rad neck and spilling over a bit. I shut off car at 213 degrees.

All good, except your last comment.

If you again tried to burp the radiator, then leave the radiator cap on and let the Jeep cool. Cold start your Jeep and test the upper rad hose again. Although you said it never got warm, was it flowing as soon as you started the engine?

Have we talked about the radiator cap yet? Is it holding a good seal?

Gotta be honest, I think the t-stat needs to be replaced. But the upper hose will tell you everything you need to know if you cold start the engine and check for immediate flow.

 

[Anybodyhome]

I discovered my t-stat was bad when I got a P0128- Coolant Thermostat Temperature Below Regulating Temperature.

The first thing I did was check coolant level, and watch the overflow when I ran the engine at idle for a while. I then let the Jeep cool and cold-started it, ran around to the front and wrapped my hand around the upper rad hose. I immediately felt water flow and knew the t-stat was stuck in the open position, allowing coolant to flow all the way through the system before the engine even heated up.

Long story short, nobody local had the t-stat I needed and I ordered an OEM from partsgeek.com. I had it in hand within a few days, replaced and ran into an issue very similar to NineLives saga right now. Had to burp it, took it our for a drive, got a bouncing, fluctuating temp gauge and went back to the house. Burped it again and let it cool. Opened the JScan app and fired up the Jeep, watched the temp gauge with my hand on the upper hose, the t-stat opened around 200-205 when I felt flow and quickly got warm as I watched the JScan temps. All good.

 

[Dirty Dog]

Swapped my headlights out the other day and here are pics of my rad. Are these fins concerning to anyone?

Bent fins on radiators are like freckles. Everybody has some. The fins are just thin bits of metal. Kamikaze bugs are enough to bend them, even without the occasional rock being tossed up. They absorb heat from the water in the channels and transfer it to the air. If the channels are damaged, that can affect water flow. But it takes a LOT of fin damage to have any real impact on cooling.

 

[JamesLaBrada]

I'm having the same issues now. I replaced the thermostat 2 times. Replaced the radiator (the coolant was dirty in the radiator), cleaned out the hoses, replaced with new coolant, and replaced the reservoir tank (the reservoir tank was leaking when the engine was running). I bleed the system using a spill free funnel and with the jeep on an incline. I then take the jeep for a test drive; the engine runs up to 240 most of the coolant runs into the reservoir tank. almost filling it up past the "max" level. The engine runs up to 240 for about a few seconds and then dropped to 208-210 and stayed there the rest of the drive. The next day I noticed the reservoir tank still had the coolant from last night's test drive. I drive the jeep again and it overheats up to 240 and stays there with the radiator fan running loud.
There is no milky oil and there's no white exhaust smoke, and there are no leaks when its running and when it's not running.
And the coolant is not boiling in the spill free funnel when I bleed it. Also, the radiator came with a new cap.

For the past couple of years, the Jeep would run hot around 215 to 230 on and off but has gotten worse in the past couple of weeks. The first time we replaced the thermostat, we had to replace the radiator fan as well (that was about 2 and half months ago)

This Jeep has been in off road parks some and some mud puddles (we stopped driving in mud puddles the 2nd time once we knew how much work we to do to clean it..) It seemed like the radiator fan kicked on more since those mud puddle adventures..

Right now, I'm thinking I need to replace the thermostat again, because the thermostat won't open until 215 (its labeled at 203)
AND why isn't the coolant not going back into the radiator? Why does it stay in the reservoir tank?

Please let me know if I'm missing something. Any help is greatly appreciated!

2015 Jeep JK Wrangler

 

[BLACKJKU]

I'm having the same issues now. I replaced the thermostat 2 times. Replaced the radiator (the coolant was dirty in the radiator), cleaned out the hoses, replaced with new coolant, and replaced the reservoir tank (the reservoir tank was leaking when the engine was running). I bleed the system using a spill free funnel and with the jeep on an incline. I then take the jeep for a test drive; the engine runs up to 240 most of the coolant runs into the reservoir tank. almost filling it up past the "max" level. The engine runs up to 240 for about a few seconds and then dropped to 208-210 and stayed there the rest of the drive. The next day I noticed the reservoir tank still had the coolant from last night's test drive. I drive the jeep again and it overheats up to 240 and stays there with the radiator fan running loud.
There is no milky oil and there's no white exhaust smoke, and there are no leaks when its running and when it's not running.
And the coolant is not boiling in the spill free funnel when I bleed it. Also, the radiator came with a new cap.

For the past couple of years, the Jeep would run hot around 215 to 230 on and off but has gotten worse in the past couple of weeks. The first time we replaced the thermostat, we had to replace the radiator fan as well (that was about 2 and half months ago)

This Jeep has been in off road parks some and some mud puddles (we stopped driving in mud puddles the 2nd time once we knew how much work we to do to clean it..) It seemed like the radiator fan kicked on more since those mud puddle adventures..

Right now, I'm thinking I need to replace the thermostat again, because the thermostat won't open until 215 (its labeled at 203)
AND why isn't the coolant not going back into the radiator? Why does it stay in the reservoir tank?

Please let me know if I'm missing something. Any help is greatly appreciated!

2015 Jeep JK Wrangler

When you say on a incline would that have put the front of the Jeep at least 6" higher in the front than the rear?

What Brand of T-stats are you using?

 

[Anybodyhome]

Another possibility is this: although your drained all the coolant when replacing the radiator and the reservoir, there remains some coolant inside the engine. This may be why you may have more coolant in the reservoir.

Also, have you tried cold starting the engine with a hand around the lower radiator hose to see if coolant is flowing from the radiator to the engine?
The only way coolant gets to the reservoir is if the radiator is full and it's pushing overflow to it.

But it does sound as though there is an intermittent blockage of some sort going on. That's the only explanation for properly flowing coolant and an overheating engine occurring simultaneously. I suppose you could have a bad ECT sensor, but that would be a last resort.

 

[JamesLaBrada]

When you say on a incline would that have put the front of the Jeep at least 6" higher in the front than the rear?

What Brand of T-stats are you using?

Murray Plus

 

[JamesLaBrada]

Another possibility is this: although your drained all the coolant when replacing the radiator and the reservoir, there remains some coolant inside the engine. This may be why you may have more coolant in the reservoir.

Also, have you tried cold starting the engine with a hand around the lower radiator hose to see if coolant is flowing from the radiator to the engine?
The only way coolant gets to the reservoir is if the radiator is full and it's pushing overflow to it.

But it does sound as though there is an intermittent blockage of some sort going on. That's the only explanation for properly flowing coolant and an overheating engine occurring simultaneously. I suppose you could have a bad ECT sensor, but that would be a last resort.

View attachment 124086

Thanks for the info. I checked the bottom hose and it felt like it lacked coolant… felt soft when I started the engine. Eventually I felt coolant, I squeezed on the hose a little and we saw some air bubbles as we were tuning the engine. Well…. long story short I believe we were at the beginning stages of a a blown head gasket, because the coolant started to actually boil in the spill free funnel…… it’s never boiled before. Ugh…. Well thanks for all the help. Looks like I’ll shopping for a new vehicle….. my Jeep days are over….

 

[Speartip]

Thanks for the info. I checked the bottom hose and it felt like it lacked coolant… felt soft when I started the engine. Eventually I felt coolant, I squeezed on the hose a little and we saw some air bubbles as we were tuning the engine. Well…. long story short I believe we were at the beginning stages of a a blown head gasket, because the coolant started to actually boil in the spill free funnel…… it’s never boiled before. Ugh…. Well thanks for all the help. Looks like I’ll shopping for a new vehicle….. my Jeep days are over….

Was going to offer a possible solution to @ JamesLaBrada problem as I went thtew a similar set of issues. It wasnt a blown head gasket in my case . Just a real finicky air pocket and T Stat. Runs perfect 8 months since figuring it out He’s obviously gone now and a possible chance misdiagnosed issue .
Glad I didn’t waste my time typing cause it would have been a rather long post explaining .
I’m really starting to dislike these one & done’s.
Waste somebody else’s time .
Rant Over

 

[Anybodyhome]

Thanks for the info. I checked the bottom hose and it felt like it lacked coolant… felt soft when I started the engine. Eventually I felt coolant, I squeezed on the hose a little and we saw some air bubbles as we were tuning the engine. Well…. long story short I believe we were at the beginning stages of a a blown head gasket, because the coolant started to actually boil in the spill free funnel…… it’s never boiled before. Ugh…. Well thanks for all the help. Looks like I’ll shopping for a new vehicle….. my Jeep days are over….

Not feeling coolant flow thru the bottom hose is not the sign of a head gasket going bad. The engine starts and the water pump starts along with everything else. If no coolant is flowing when the engine starts, there is either air in the loop or the water pump is going bad.

The coolant isn't "boiling," it's actually the air bubbles in the system for one of 2 reasons: either it's not been thoroughly burped or, as you suggest, the head gasket could be going. A bad head gasket will allow the pressurized air in the cylinder heads to transfer to the cooling system- forcing air into the cooling loop.

Next step for me would be a pressure test. Is there a reliable radiator shop or a trusted mechanic nearby? It doesn't take very long and is relatively easy test to perform.

 

[JamesLaBrada]

Not feeling coolant flow thru the bottom hose is not the sign of a head gasket going bad. The engine starts and the water pump starts along with everything else. If no coolant is flowing when the engine starts, there is either air in the loop or the water pump is going bad.

The coolant isn't "boiling," it's actually the air bubbles in the system for one of 2 reasons: either it's not been thoroughly burped or, as you suggest, the head gasket could be going. A bad head gasket will allow the pressurized air in the cylinder heads to transfer to the cooling system- forcing air into the cooling loop.

Next step for me would be a pressure test. Is there a reliable radiator shop or a trusted mechanic nearby? It doesn't take very long and is relatively easy test to perform.

Thank you. I’ll look into it. It’s just frustrating going through this and not finding a solution yet. It’s been a few months now and it seems like the Jeep just gets worse as the days move forward….. rant over lol

 

[JamesLaBrada]

Here’s a video of the spill free funnel from last night…

 

[BLACKJKU]

Murray Plus

Not the brand I would use unless I knew who made them for Murray, Gates is about the only brand I use.

 

[Anybodyhome]

Here’s a video of the spill free funnel from last night…
View attachment 124089

Yeah... here's what I'm seeing and hearing:

The coolant is bubbling at the same pace/RPM/rate as the engine is running, if that makes any sense. In other words, if you increased the RPM of the engine, the coolant bubbling would keep pace with the engine. Does that make sense? Not sure how to explain it otherwise.
But it does give me cause for concern that there is air being forced from a cylinder head into the coolant, which is an indication of a head gasket going south.

Maybe someone else can verify, but if a head gasket is going bad, wouldn't there be indications of this somewhere on the engine itself?

 

[BLACKJKU]

Yeah... here's what I'm seeing and hearing:

The coolant is bubbling at the same pace/RPM/rate as the engine is running, if that makes any sense. In other words, if you increased the RPM of the engine, the coolant bubbling would keep pace with the engine. Does that make sense? Not sure how to explain it otherwise.
But it does give me cause for concern that there is air being forced from a cylinder head into the coolant, which is an indication of a head gasket going south.

Maybe someone else can verify, but if a head gasket is going bad, wouldn't there be indications of this somewhere on the engine itself?

When your increasing the RPM's the water pumps speed is also increasing. Also it depends on where the head gasket blows, i've heard them blow so it sounded like a tea pot it was blowing out of the side of the head and not into a water port.

A pressure test and a combustion gas test for the coolant is the only way to really know.