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EcoDiesel constantly overheating - replaced most cooling system parts. HELP!

24K views 61 replies 20 participants last post by  Bounty Hunter 
#1 ·
I have a 2014 Jeep Grand Cherokee Summit with the 3.0L EcoDiesel and I've been struggling to resolve an overheating issue for the past few months. It's virtually undriveable and you have to drive it extremely gentle as to not make it overheat. I am mechanically inclined and do all of my own maintenance, and this has all begun when a dealership released the vehicle back to me with the expansion tank cap removed, which immediately overheated 10 minutes after picking up the vehicle. I've had nothing but problems since then.

The issue can be repeatedly duplicated and the engine will begin to overheat if there's any sort of load (climbing a decent grade on the freeway or surface streets, WOT, etc). If you back off and slow down, the temperatures will decrease and you can prevent it from overheating. Running at 75 mph on a flat freeway, the oil temps are steadily around 221 degrees and the coolant gauge needle is a bit elevated. To compare, the oil used to run around 205 degrees while cruising on the freeway. If you continue to push it just a little (even WOT while going downhill), the coolant temperature increases, oil temperature increases to over 232 degrees and then it will reach the "point of no return" and immediately overheat (coolant will increase its temperature to maximum, oil temperatures will increase to 270+ degrees if you attempt further driving, etc).

When driving it (and not overheating), I can turn on the heater and it will blow extremely hot air. When it's fully overheating (coolant temperature gauge is maxed out, and about 235 F according to AlfaOBD), I can turn on the heater inside the vehicle and there is NO HEAT! Additionally, the air coming off of the radiator at this time feels extremely cool, as if the radiator isn't even hot.

I have replaced the thermostat, and have duplicated the issue with the thermostat removed from the housing. After this, I discovered that the water pump was leaking, so I have also replaced the water pump with a brand new OEM Mopar water pump and all accompanying seals/o-rings. Concerned that there was a blockage in the radiator or heater core, I reverse flushed the radiator, heater core and engine, and then drove around for a few days with a chemical cleaner. After this, I reverse flushed everything again, used a professional strong chemical cleaner, reverse flushed again and then refilled with Mopar 68163848AB coolant mixed down to 50/50. Vacuum fill tool confirms that there are no leaks present in the cooling system. The EGR cooler was replaced under its recall warranty about 3,000 miles ago. Wondering if it was a warped head due to past overheating, I attempted to check for combustion leaks using the UView Combustion Leak Tester, but there are no combustion gasses present in the expansion tank.

Does anyone have any ideas why this could be happening? Thanks so much for any insight!
 
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#4 ·
Unfortunately, it's not just an air pocket. It was drained and refilled 5 times now, each time with a vacuum fill tool to ensure that it gets filled with no air. Additionally, the water pump is brand new as referenced in my first post. Thanks for your help! 🙂
 
#6 ·
I don't believe that the 3-way valve exists on the Jeep Grand Cherokee platform. I can't find the valve on my vehicle, I can't find any applicable part numbers for my Jeep and the cooling system diagram for the Jeep doesn't show a 3-way valve anywhere.
 
#13 ·
No heat thru the heater core and the Radiator is not hot ? Definitely a coolant flow issue.
Exactly. No heat coming off of radiator and no heat out of air vents when it's overheating indicates that there's no circulation happening, BUT when it's at normal operating temperature (cruising on the freeway and being careful of load), I will have full circulation (heat coming off of radiator and heat out of air vents). When it overheats, fans come on extremely high.

Thinking back, the issue started around the time that I had the dealer replace a leaking oil cooler hose. Is it possible that they accidentally got some sort of debris in the oil cooler when the hose was off, and thus causing an internal blockage within the oil cooler? Is there any way to test the oil cooler without fully replacing the oil filter housing and accompanying oil cooler?
 
#21 ·
I'm extremely confident that there's not an air lock. Today, for good measure, I drained about a gallon of coolant and pulled another vacuum with my vacuum fill tool with the heater on to ensure access to the heater core, and slowly filled the system while stopping and pulling additional vacuum. I repeated this process 4 times, and watched all of the hoses go from collapsed under vacuum to filled with coolant. I purposely overfilled the system and then manually suctioned out the approipate amount of coolant from the expansion tank to ensure a proper fill with no air. Afterwards, I brought the engine to temperature and left it idle with the heater on, parked on an extremely steep street with the radiator cap removed to provide any possible air pockets an opportunity to travel up and escape. No changes. I purchased and replaced the radiator cap afterwards for good measure, and again, no changes. I verified the radiator fan operation using AlfaOBD and watched the radiator fan duty cycle increase as coolant temperatures increased while driving, along with physically stopping and checking that the fans were actually running. Both low speed and high speed operations are functioning.

I don't know what else it could be, other than a faulty/plugged oil cooler. I just placed an order for an entirely new oil filter housing with the attached oil cooler, and I will have it in about a week. In the meantime, does anyone else have any other ideas of what can be causing this? This is unbelievable!
 
#28 ·
My Jeep Grand Cherokee Summit doesn't have active grille shutters.

Did you ever confirm the Jeep Eco definitely does not have a 3 way valve?
It does not have the 3-way valve. I can't find it anywhere on the vehicle where it exists on the RAM's, there's no corresponding part numbers for the Jeep's and it doesn't exist in any of the Jeep cooling system diagrams.

This sounds like the same exact problem I had with a 2013 dodge dart. It would over heat when it was pushed or shut off then restarted. no one could figure it out. I went for the problem myself and found that when the car got hot there was a hole or a crack in one of the cylinders that would cause this to happen.
Sheesh.. I hope that's not the case here!
When the fans came on could you feel the heat being pulled from the radiator or was the air cold? cool? warm? or hot ?
When the engine is HOT and running in the driveway, the air coming off of the radiator when the fan is running is just "warm".

If the heater doesn't output heat and the radiator isn't hot when its overheating you have an issue with coolant flow.
Validate the above with a IR thermometer. (top rad hose should be inline with the indicated temp before it overheats then not inline with the indicated temp when it overheats)

If the above is true, the flow could be impacted by the one of the following (flow obstruction (air or blockage or engine pressurization) / water pump / thermostat / coolant valve if it exists).
If the engine is injecting air into the system you will be typically be pushing out coolant; I didn't get that you were pushing coolant and your test didn't indicate exhaust in the coolant. (heads can be a bugger to figure out, in BMW land you see a pile of head issues which only manifest as overheating)

Can you validate coolant flow?
With a cold engine, if you start the jeep with the radiator open can you tell when the tstat opens as the engine warms? Basically looking to validate that you have coolant flow when the tstat is open.

My guess is that you don't have enough flow to start, next guess being that flow restricts when it gets hot (unlikely).
Out of curiosity have you pressure tested it hot? Another thing you can do is put a pressure tester on when cold and do a regen to get it hot and watch the pressure rise in the system. If the pressure is to low in the system it could be boiling your coolant.
Responding to both of you in this message. There's some excellent ideas here so I went out and purchased a radiator pressure tester that's compatible with the neck on my Jeep Grand Cherokee. I started with a cold engine, and let the pressure build naturally (I didn't pump any pressure into the cooling system). I left it idle for about 15 minutes, and then initiated a manual DPF regeneration cycle with AlfaOBD. The most that the system reached during the regen cycle was 7 psi, and everything was at full operating temps. Using an IR thermometer, during the regen cycle, the upper radiator hose was 173*F and the lower radiator hose was 144*F (about a 30*F differential). Once the regen cycle completed, I left it idle for about 10 minutes, and these two radiator hoses equalized in surface temperatures.

After this 10 minute idle period, I held the RPM at 2000 RPM while stationary on the driveway and after a few minutes, everything got real hot - oil heated to 223*F and coolant heated to 213*F (which is the next step up from the middle on the coolant temp gauge inside the cabin, so clearly starting to overheat just sitting stationary - the Jeep uses an analog gauge). Radiator fans were only running very low. Using the IR thermometer, both the upper and lower radiator hoses were at 196*F, the coolant hose entering the EGR cooler was 194*F, the oil cooler hose was at 122*F, and the radiator fins had a 95-105*F surface temp from the best that I could tell, shooting through the grille. At the end of all this, the most that the cooling system ever reached at the expansion tank was 12 PSI.

So, what does this tell me? Does the oil cooler indeed have an internal blockage considering its hose is around 74*F cooler? Why do the radiator fins have such a low surface temp? Is the hot coolant stopping at the oil cooler and not passing through and making its way to the radiator, thus also being the reason for such high oil temps with no load? Why is the overall system pressure so low? Shouldn't it have reached its full pressure (Around 20 psi? Or am I mistaken?) by the end of all of this?

Thanks again to everyone for their insight. It is truly and genuinely appreciated.
 
#25 ·
This sounds like the same exact problem I had with a 2013 dodge dart. It would over heat when it was pushed or shut off then restarted. no one could figure it out. I went for the problem myself and found that when the car got hot there was a hole or a crack in one of the cylinders that would cause this to happen.It would only happen when you would stop the engine then start again, then it would boil out of the tank on the ground. It was putting a pressurized air pocket in the system. God only knows what the pressure was. So Dodge would not admitt to any of this so I went ahead and drained the cooling system, rinsed it really well, vacuumed it and filled it with clean water, put a can of block seal in it under pressure with a radiator pressure tester when it was cold. I kept the pressure at 21lbs untill it reached full operating temp. Then let it cool, all the time keeping 21lbs of pressure on the system until cold. All the heating problems dissapeared and it worked great for many thousands of miles until I traded it in...... Just a suggestion??
 
#27 ·
If the heater doesn't output heat and the radiator isn't hot when its overheating you have an issue with coolant flow.
Validate the above with a IR thermometer. (top rad hose should be inline with the indicated temp before it overheats then not inline with the indicated temp when it overheats)

If the above is true, the flow could be impacted by the one of the following (flow obstruction (air or blockage or engine pressurization) / water pump / thermostat / coolant valve if it exists).
If the engine is injecting air into the system you will be typically be pushing out coolant; I didn't get that you were pushing coolant and your test didn't indicate exhaust in the coolant. (heads can be a bugger to figure out, in BMW land you see a pile of head issues which only manifest as overheating)

Can you validate coolant flow?
With a cold engine, if you start the jeep with the radiator open can you tell when the tstat opens as the engine warms? Basically looking to validate that you have coolant flow when the tstat is open.

My guess is that you don't have enough flow to start, next guess being that flow restricts when it gets hot (unlikely).
 
#32 ·
Get one of those temperature guns. Test the plumbing and components of the cooling system.

My own suspicion, despite all your hard work and careful analysis, is that the radiator may have blockages due to partial internal collapse.

I had very similar symptoms to you one. Took ages and tons of $$$$ to pin point the issue.
 
#33 ·
Get one of those temperature guns. Test the plumbing and components of the cooling system.

My own suspicion, despite all your hard work and careful analysis, is that the radiator may have blockages due to partial internal collapse.

I had very similar symptoms to you one. Took ages and tons of $$$$ to pin point the issue.
I flushed the radiator both ways with a radiator flush gun connected to both shop air and a garden hose, and flow was extremely good. Wouldn't flow be constricted in this case, if there was an internal issue/blockage?
 
#34 ·
Your temps and pressures during regen were good. What is confusing is your temp readings vs actual. These thermostats start opening at 208 F and are not fully open tell 228 F. Just going off your analog gauge readings might be the issue, there could be something wrong in the bcm settings or just the gauge itself. Are you getting overheat messages or possible limited speed warnings?
 
#35 ·
It's not a malfunctioning gauge and it's actually overheating, unfortunately. When the temperature starts to rise, and if I don't decrease engine load or pull over, the temperature will shoot all the way up to max. When this happens, oil temperatures will increase to 260-270+ if you continue to drive the vehicle, overheat warnings display, speed is limited, etc. I can open the hood at this point and the coolant is severely expanded due to heat and overflowing out of the expansion tank via the overflow tube.
 
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