2006 CRD Limited Loosing Coolant... Pass Cold Engine Test.

thomasnelson

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Hi All.

I need help figuring this out...I know this has been covered many time before... but none of the previous solutions fit here...

Situation. Every few days, not all, I get a LoCOOL message on the instrument cluster and have to top off the reservoir. The distance driven can vary from 10 miles to 400 miles. I preformed a Cold Engine Test. After 5 minutes there is absolutely no pressure in the reservoir. And after the thermostat opens at full operating temp there is still no pressure in the reservoir. But driving about 10 miles pressure starts to build yet no coolant loss at this time.

For some reason the system loses coolant after being driven yet there is no signs of a leak on the ground and the engine start normally... no indication the coolant is entering the cylinders and burning off.

I was thinking I might have a crack in the reservoir but I soaped the whole thing down looking for leaks.. found none.

I am the original owner, Had the EGR deleted in 2019, Running GDE EcoTune Full torque.
 

turblediesel

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It must be going somewhere. Water pump weeping? There are a lot of little elbow hoses in there. The elbow on the engine oil cooler gets a lot of heat. Maybe the "LOW COOL" level switch is hanging up.

Other options are cracked head or bad head gasket.
 

thomasnelson

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I've checked the reservoir for exhaust gases with a chemical tester... Negative. That should rule out a bad head gasket correct?? Are there any other signs that would indicate a cracked head??

I'll recheck all the hoses again and report back.
 

lfhoward

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Check your oil. If a head is cracked your coolant could be in your oil pan.
 

thomasnelson

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No coolant in the oil pan... nothing but fresh oil.

It seems to lose the coolant after I turn off the engine. I've check the levels before I take off and when I get to my destination and there is no change. After the Jeep sits for a while, when I recheck, the level has dropped. Still no coolant on the ground.
 

Michael Wolfe

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So somewhere it's consuming coolant, then when the system cools, and the remaining coolant contracts, it draws from the reservoir as designed.
If there are no physical leaks, (radiator, water pump weeping, heater core, viscous heater, not leaking at any plugs where the EGR components fell off, and all connecting hoses) then it must be passing into the engine oil, or maybe the transmission (if your transmission oil cooler is part of the radiator), otherwise it's going out the tailpipe. I assume you don't smell coolant anywhere.
Unless it's a very small amount, oil would turn milky. a small amount may boil off since the oil gets hotter than 212 in various parts of the engine.
unless the head is cracked somewhere that lets the coolant enter the intake or exhaust side of the valves, I would think your coolant would be pressurized.
Have you actually ran a pressure test of your cooling system? I mean pressurize the system to the rated cap pressure while the vehicle is off with a cap adapter? If you can't find a physical leak, then either way, the head is most likely going to have to come off.
 

Billwill

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Have you checked the "Low Coolant Sensor" connected to the bottom of the plastic reservoir?

This is fitted in somewhat loosely with a thin rubber O ring.

My sensor got slightly dislodged and slowly leaked water out years ago.

I fitted a new O ring and to be on the safe side sealed the whole lot with Permatex sealer.

In my case I could see the slight leak though.;)
 

thomasnelson

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So somewhere it's consuming coolant, then when the system cools, and the remaining coolant contracts, it draws from the reservoir as designed.
If there are no physical leaks, (radiator, water pump weeping, heater core, viscous heater, not leaking at any plugs where the EGR components fell off, and all connecting hoses) then it must be passing into the engine oil, or maybe the transmission (if your transmission oil cooler is part of the radiator), otherwise it's going out the tailpipe. I assume you don't smell coolant anywhere.
Unless it's a very small amount, oil would turn milky. a small amount may boil off since the oil gets hotter than 212 in various parts of the engine.
unless the head is cracked somewhere that lets the coolant enter the intake or exhaust side of the valves, I would think your coolant would be pressurized.
Have you actually ran a pressure test of your cooling system? I mean pressurize the system to the rated cap pressure while the vehicle is off with a cap adapter? If you can't find a physical leak, then either way, the head is most likely going to have to come off.

No signs of leaks on the ground.
No Coolant in the oil. Not Milky
Exhaust doesn't smell like coolant is passing through the engine.
Chemical coolant test doesn't indicate exhaust gases.
Reservoir not pressured after several minutes when starting from Cold. Does slowly pressurize after reaching full operating temp and thermostat opens.
Don't have the means to pressurize the system with the engine off.
Don't really want to "pop the top" unless justified. I don't have the fund for a mechanic to go on a fishing expedition.
 

thomasnelson

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Have you checked the "Low Coolant Sensor" connected to the bottom of the plastic reservoir?

This is fitted in somewhat loosely with a thin rubber O ring.

My sensor got slightly dislodged and slowly leaked water out years ago.

I fitted a new O ring and to be on the safe side sealed the whole lot with Permatex sealer.

In my case I could see the slight leak though.;)


I was thinking the reservoir may have a crack or something, but never thought about the sensor O-ring... I'll check this afternoon if it doesn't storm today.
 

William Waddy

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I've been having a similar problem and hope you will keep posting as you work through this. Thanks! I did run some head gasket sealant through the system and it has slowed down the leak, but not stopped completely. Just like you, no milky oil, no apparent leaks, no white exhaust, etc.
 

SOMD-JeepFan

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I've been having a similar problem and hope you will keep posting as you work through this. Thanks! I did run some head gasket sealant through the system and it has slowed down the leak, but not stopped completely. Just like you, no milky oil, no apparent leaks, no white exhaust, etc.
Thomas and William,

Have either of you resolved your issue? I am experiencing the same issue, but have not started tracking down my leak. I will start looking to see if I can determine where my coolant is going. As long as I am just running around locally, I am good, but the longer rides force me to top off sooner.
 

William Waddy

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I did just resolve my issue. Turns out there was a small leak in one of the small houses into the thermostat housing. It would only leak when under high load, and the fluid would pretty much evaporate before dripping, so that explains why I never saw a leak, never had white smoke out the exhaust, or never had fluid in the oil. I'm really glad it's not a head gasket.
 

SOMD-JeepFan

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I did just resolve my issue. Turns out there was a small leak in one of the small houses into the thermostat housing. It would only leak when under high load, and the fluid would pretty much evaporate before dripping, so that explains why I never saw a leak, never had white smoke out the exhaust, or never had fluid in the oil. I'm really glad it's not a head gasket.
How did you end up finding it? Did you use a radiator pressure tester kit? I have been watching videos to determine where all the different coolant lines are located.
 

William Waddy

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How did you end up finding it? Did you use a radiator pressure tester kit? I have been watching videos to determine where all the different coolant lines are located.
Found it totally by accident. I had it out the other day doing a steep trail in 4low. It was a very hot day (115F+) and I had the AC going. The engine started to overheat because I had forgotten to turn on the AC cooling fan (I replaced the factory fan and installed a larger fan with a manual switch). Looking under the hood when it was overheated, I could see some steam and slight spray coming out from under the small hose at the thermostat. Once I hit the fan switch and got things cooled down there was no visible leaking and no more overheating. I would never have found it if it hadn't forgotten to turn on the AC fan and had the engine overheat. It still slowly loses coolant - the low coolant light comes on after 1-2 hours of driving, but now I know what's causing it - i think. I'll replace the hose next week and then will be able to test and know for sure whether or not that takes care of the problem.
 
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William Waddy

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Finally got that thermostat hose replaced. It appears that fixed the problem. The shop said that hose is no longer available as a spare part, but they managed to rig something up.
 

thomasnelson

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Hey all. Sorry for the absence. My time has been spent trying to about a child so my 4wheel child was a little neglected.

I too have jest found the leak I’ve been experiencing. Turns out a hose clamp was not in place coming from the thermostat going to the rear of the engine bay. The hose had a tight fit but still needed a hose clamp. As the pressure built up there was a very fine mist spraying from the hose.

Thanks to all who chimed in.
 

thomasnelson

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Hey all. Sorry for the absence. My time has been spent trying to adopt a child so my 4wheel child was a little neglected.

I too have jest found the leak I’ve been experiencing. Turns out a hose clamp was not in place coming from the thermostat going to the rear of the engine bay. The hose had a tight fit but still needed a hose clamp. As the pressure built up there was a very fine mist spraying from the hose.

Thanks to all who chimed in.
Oh… forgot to report that the dealership and two separate shops preformed a coolant pressure test. They all said that they found no leaks or seen any abnormal pressure readings. I found it by tracing out every hose in the engine bay.
 
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