Coolant expansion level to high

[cwieland]

2020 Gladiator - My coolant level has always been good. Cold level on tank then somewhere between there and full hot when warmed up. Now the tank is filling up to near full when running and then back to the cold level when off and cold. The idiot temp guage does not move off normal when warmed up. The engine gauges show temps ranging from about 210 to (the highest I have seen) 231 averaging around 224. I have no check engine light and no codes. When I called a dealer they told me it was normal and with the engine running fine and no check engine light there was nothing they could do.

To make matters worse we are at the beginning of a 15000 mile Alaska journey.

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[Hootbro]

Now the tank is filling up to near full when running and then back to the cold level when off and cold.

What do you mean by "full"? Like to the full hot line or full about to the level of the fill cap?

If the former, does sound about normal, if the latter, then there is a problem.

 

[ShadowsPapa]

2020 Gladiator - My coolant level has always been good. Cold level on tank then somewhere between there and full hot when warmed up. Now the tank is filling up to near full when running and then back to the cold level when off and cold. The idiot temp guage does not move off normal when warmed up. The engine gauges show temps ranging from about 210 to (the highest I have seen) 231 averaging around 224. I have no check engine light and no codes. When I called a dealer they told me it was normal and with the engine running fine and no check engine light there was nothing they could do.

To make matters worse we are at the beginning of a 15000 mile Alaska journey.

I have no idea what your ambient/air temperatures are right now, but those temps seem a bit high to me if you aren't towing or operating in mountains.
You should see 195 or so to 220 when unloaded and not up in the mountains and thin air.

Need MORE INFO as far as your air temps, where and how you are driving, loaded or not, towing or not.

 

[cwieland]

Need MORE INFO as far as your air temps, where and how you are driving, loaded or not, towing or not.

With and without trailer at around 80 degrees. Today at around 70 degrees 6000 ft unloaded. The symptoms don’t vary much but the high temp did not go over 225 that I saw.

 

[cwieland]

What do you mean by "full"? Like to the full hot line or full about to the level of the fill cap?

If the former, does sound about normal, if the latter, then there is a problem.

It’s to the top of the tank. Well above the full hot mark.

 

[ShadowsPapa]

With and without trailer at around 80 degrees. Today at around 70 degrees 6000 ft unloaded. The symptoms don’t vary much but the high temp did not go over 225 that I saw.

That seems high unloaded.
(even for that altitude)

I wonder about the condition of the cap on that reservoir.
Otherwise, I'd say you have an issue causing abnormally high temperatures. And a bad cap can contribute to that, especially at higher altitudes.

 

[cwieland]

That seems high unloaded.
(even for that altitude)

I wonder about the condition of the cap on that reservoir.
Otherwise, I'd say you have an issue causing abnormally high temperatures. And a bad cap can contribute to that, especially at higher altitudes.

I replaced the cap a few years ago but that would make sense. I was wondering about what a failing thermostat would look like.
It is running great except for this symptom. Two dealers tried to tell me this was normal even though it has never done this in the almost 6 years I’ve had it. They wouldn’t even look at it without a check engine light.

 

[kevman65]

The new fangled parts changers don't know what to look for if the computer doesn't tell them.

The days of old fashioned diagnosis are long gone.

 

[ShadowsPapa]

I replaced the cap a few years ago but that would make sense. I was wondering about what a failing thermostat would look like.
It is running great except for this symptom. Two dealers tried to tell me this was normal even though it has never done this in the almost 6 years I’ve had it. They wouldn’t even look at it without a check engine light.

Loose/leaking pressure cap causes low pressure, and the hot spots can "boil" leading to higher temps.

An iffy thermostat can cause engine temperatures to run high if it doesn't open far enough or quick enough. These aren't rated to fully open until somewhere in the 220 range, which is pretty typical. Over the decades, 215-225 or so was pretty common for a "fully open" temperature of a thermostat. The rating, for example, a 195 stat, starts to open at 195.

Water pump impeller unable to keep the coolant flow moving - not really common, but an impeller can work loose meaning it won't spin as fast as it should. Those always get worse, never better.

Fan controller - if you have a tazer or JSCAN, it would be interesting to force the fan into high mode and see what happens with the temperatures.

Other "mountain men" can chime in, but it seems even at that altitude, no payload, no trailer, nothing unusual, those operating temperatures are more what I'd expect with a loaded truck, not unladen.

 

[cwieland]

Loose/leaking pressure cap causes low pressure, and the hot spots can "boil" leading to higher temps.

An iffy thermostat can cause engine temperatures to run high if it doesn't open far enough or quick enough. These aren't rated to fully open until somewhere in the 220 range, which is pretty typical. Over the decades, 215-225 or so was pretty common for a "fully open" temperature of a thermostat. The rating, for example, a 195 stat, starts to open at 195.

Water pump impeller unable to keep the coolant flow moving - not really common, but an impeller can work loose meaning it won't spin as fast as it should. Those always get worse, never better.

Fan controller - if you have a tazer or JSCAN, it would be interesting to force the fan into high mode and see what happens with the temperatures.

Other "mountain men" can chime in, but it seems even at that altitude, no payload, no trailer, nothing unusual, those operating temperatures are more what I'd expect with a loaded truck, not unladen.

To follow up, first Thank you for the education. The symptoms really seemed like it was not able to hold pressure which goes back to your first suggestion being the expansion tank cap. I really wanted to pressure test it and the system but being on the road I was unable to do that. I did a visual and unable to find anything obvious. I finally found a dealer to take a look and they found a crack in the hose connection on the bottom of the expansion tank. Apparently not big enough to present as a leak but big enough to prevent the pressure to build in the tank. So your first suggestion of the cap was spot on. Anyway I have an extended warranty and fortunately they had the tank and after a week of driving I am pronouncing it cured. Thanks for your help.

 

[Lost1wing]

To follow up, first Thank you for the education. The symptoms really seemed like it was not able to hold pressure which goes back to your first suggestion being the expansion tank cap. I really wanted to pressure test it and the system but being on the road I was unable to do that. I did a visual and unable to find anything obvious. I finally found a dealer to take a look and they found a crack in the hose connection on the bottom of the expansion tank. Apparently not big enough to present as a leak but big enough to prevent the pressure to build in the tank. So your first suggestion of the cap was spot on. Anyway I have an extended warranty and fortunately they had the tank and after a week of driving I am pronouncing it cured. Thanks for your help.

Coming back and posting the fix really helps others. I wish more would do that. Thank you and enjoy your trip.

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