Coolant Low

[CROW]

Truck is 2018 3500 with 39k This is showing up on the instrument panel with a battery symbol. Coolant is not low though I did add about a quart after first had this display. No leaks. Gotta tow a large fifth wheel in about a week and am wondering what is going on. Wonder what turns this on?
Do not have a code reader but no check engine light on .

 

[JR]

If the coolant level is proper I'd look into the battery light. Low voltage causes all kinds of red herrings on my rig.

 

[Grumpy8811]

low coolant sensor.. Geno's, Amazon, Rock Auto.. less than 20 bucks..

 

[AH64ID]

My 2022 did that a few times. Look to be an acceptable level but it took about 1 quart to top off and the light hasn’t been back in over 2 years.

 

[Wiredawg]

GS Brockman had to replace the coolant sensor on his 2018 Ram 4500. Cant recall if he posted here or not, but might help to search it.

 

[CROW]

Well guess what? I filled the coolant bottle twice. Took about a quart total and the light stayed on. I ordered the part (which I can return)and a day later the light did not come on and has stayed off for a couple days.
Thanks for all the input, never knew we had a low coolant sensor

 

[Topzide]

Another thing to pay attention to if the low coolant light comes on, and that is that the coolant bottle may have split at the seem. It'll look fine, but when the heat builds in the system and under the hood, it'll open up and leak coolant! Then there is another issue with "slime" build up on the sensor "float". That's what I've been dealing with since my coolant change. It's a pain to work on the bottle with where it's located, pulling the inner liner, and then have to bend your arms in ways that their not meant to!

 

[CROW]

Well guess what?? The low coolant light came on and stayed on for almost all of the almost 700 mile trip I just completed towing my fifth wheel. Not low on coolant and I monitored engine temp on the trip carefully and it was normal. No coolant loss. Think I can conclude the sensor is faulty. I still have the replacement part. In looking I do not see where the low coolant sensor is located. Topzide has indicated it is a pain to replace.
If anyone has a diagram or instructions they could post I would certainly appreciate it.
Thanks in advance

 

[Grumpy8811]

Well guess what?? The low coolant light came on and stayed on for almost all of the almost 700 mile trip I just completed towing my fifth wheel. Not low on coolant and I monitored engine temp on the trip carefully and it was normal. No coolant loss. Think I can conclude the sensor is faulty. I still have the replacement part. In looking I do not see where the low coolant sensor is located. Topzide has indicated it is a pain to replace.
If anyone has a diagram or instructions they could post I would certainly appreciate it.
Thanks in advance

it is in the bottom of the recovery tank

 

[petersonj]

If anyone has a diagram or instructions they could post I would certainly appreciate it.

I just replaced the sensor on a 2016 truck. After removing the right wheel and inner fender liner, you will have easy access to the coolant level sensor. The sensor can be removed without draining the coolant from the reservoir. Apparently, the reservoir is self-sealing when the sensor is removed.

The sensor did not remove easily. It took a pair of pliers and lots of working it back and forth while pulling. The new sensor will not just "push in". I pressed against the sensor with a wooden handle on my hammer and used another hammer to tap it in. I you-tubed for information and found others had the same issues.

The new sensor did nothing - still have a low coolant level light.

- John

 

[Timd32]

Found this posted, describes how the inside of the tank works.

 

[Topzide]

It seems, the only way to "cure" the low coolant light is, remove the coolant tank and clean it out. Slime builds up in the tank around the sensor tube, preventing the float with magnet from reading the correct level. I have a replacement tank that's ready to put in, when weather decides to behave! I'll be able to check the seam for leakage, which I might be having. If it does check good, will go back on shelf after cleaning for a spare! If seam is bad, I'll pull the sensor and cap for spare parts.

Pulling the passenger fender liner and possible wheel for best access. A set of hose pinchers/clamps for the hoses to not have a coolant nightmare! Not a fun job, but I can get liner out and in pretty quick with all the practice over the years!

 

[petersonj]

It seems, the only way to "cure" the low coolant light is, remove the coolant tank and clean it out.

Or, just permanently jumper the coolant sensor wires and observe the coolant level visually like it has been done for decades. Just sayin'.

- John

 

[Grumpy8811]

Or, just permanently jumper the coolant sensor wires and observe the coolant level visually like it has been done for decades. Just sayin'.

- John

pretty much the truth.. it isn't like the engine is going to overheat because a person is missing a gallon of coolant out of the surge tank.

 

[Ozymandias]

I added a coolant level sensor to my 3rd Gen for this reason, cheaper then a blown engine going down the road.

 

[Ozymandias]

Or, just permanently jumper the coolant sensor wires and observe the coolant level visually like it has been done for decades. Just sayin'.

- John

If you have a blown hose or a waterpump go bad on the interstate you won't notice it until it's to late. The coolant temp sensor goes dry almost instantly in this engine as it is on top of the cylinder head, dry sensor means no reading of the overheat condition until - boom.

 

[petersonj]

I added a coolant level sensor to my 3rd Gen for this reason, cheaper then a blown engine going down the road.

Did you add the sensor to the radiator, or to the overflow reservoir?

- John

 

[Ozymandias]

To the reservoir. Not a biggy.
It's actually the same sensor as the wiper fluid reservoir, wired in parallel with that I get a Ding and a Visual if I go low on coolant.
It is installed pretty low in the reservoir, below the LOW mark, so I don't get unnecessary warnings.

 

[petersonj]

To the reservoir.

If you have a blown hose or a waterpump go bad on the interstate you won't notice it until it's to late. The coolant temp sensor goes dry almost instantly in this engine as it is on top of the cylinder head, dry sensor means no reading of the overheat condition until - boom.

So, you do realize that on the truck in your signature that your coolant reservoir won't drop if you have such a failure as mentioned above? Therefore, the low level indicator won't help, as it will still be surrounded by coolant. It will be reactions to your sense of smell and sense of sound that will determine the final outcome.

At least the 6.7 liter engines in the discussions have the reservoir as part of the pressurized cooling system, so a major leak will activate the sensor, however I am not sure how quickly the level of the reservoir would drop to activate the sensor in that situation. Also, I think that most people (including myself) would not immediately pull over and shut down the engine if a low coolant level warning lamp came on. Realistically, I think they / I would evaluate the situation by paying close attention, reducing engine load, and then pulling over at a safe location.

- John

 

[Ozymandias]

The moment you have a hole in the system and the pressure goes down it starts to suck coolant from the bottle.
I had this more then once throughout my life and the bottle was always empty.
You can also prof that, open the cock on your radiator without opening the radiators cap, it will drain your recovery bottle first.

Of course it won't work when you blow a hose of the radiator, but such an event should be recognizable from the driver.