Hi everyone, im new to this forum and actually just needed help with something i ran into today. After a 14 hour shift i went with my wife to pick up some fast food. It was about 1:30am, and we had just ordered from the drive-thru, when i noticed that my engine was running really hot, and saw that smoke or steam was coming from my radiator fluid resevoir. I immediately pop my hood and jump out, and the darn thing was nearly about to explode. I get help pushing it around to a parking spot and after a few minutes, the pressure had gone down enough that I could remove the cap safely. Upon inspection, i realized that the fluid in my resevoir was not coolant-green, and that, previous to blowing out a couple gallons of liquid something-or-other, was just at the max fill line. Now, its been raining like crazy here for a few weeks, and i splash through every puddle i see,

is it at all possible for water to enter my coolant and radiator system? Because if its not, somehow, an act of god, its a much bigger problem.

 

welcome. What is the history of the vehicle? Have you serviced its cooling system since owning it? If your overheating, it sounds like one or more of your cooling system components is not functioning properly anymore. As far as the coolant not being green, is it clear like water or is it brown and rust colored? Sounds like it time for some cooling system service and maintenance.

 

Note from DJ
Let’s start with which coolant system no you have; your Jeep came from the factory with the Closed Stem Pressure Bottle.
See photo below is this the system you still have or has it been converted to the open system with a radiator with a radiator cap and a recovery tank.

 

Hey!! That's my wife's Jeep. LOL.

 

I have not serviced or replaced the coolant system in my time owning it, but i know that the previous owner had the radiator replaced?

as far as the color of the fluid, it's more clear than anything else.

 

exactly like the picture

 

Do you live in a freezing climate? It might be that your PO was a cheap nitwit and just put water in the thing instead of coolant. If you haven't had freezing weather, it won't do much harm other than allowing more corrosion than normal.

Likely your system needs a good flush and may need other things.

 

Note from DJ
My answer to your question; “Is it at all possible for water to enter my coolant and radiator system”.
Is I can’t think of any way this is possible because this system is under positive pressure at all times except when the engine is at its total cool down temperature.

Are you sure the pressure bottle has just water in it; and not that because you can’t see the green color that you normal see you are making the assumption that the bottle has clear water in it when in fact it is totally empty?

 

I had actually been the last one to put any fluid in, and it was just regular ol pre-mixed coolant from the auto shop. Before that, as far as i i know, it was the same, pre-mixed stuff.

no freezing weather, but it has gotten close. I live in central california.

as far as the possibility of water entering at total cool down, i had been parked for about 12 hours in rainy weather, from noon to midnight? So it may have just gotten cold enough. Idk, im not really automotively literate.

It was definitely full of liquid last night. But this morning it was near empty. So strange.

 

Then screw a cap on the thing... a sealed system doesn't work well if it's, well, not sealed!

I must correct you. Ethylene glycol and propylene glycol, in addition to lowering the temperature at which the mixture in water freezes, also raise the temperature at which the solution boils. The boiling temperature is raised further relative to its pressure above atmospheric pressure.

I do agree that a new-to-you system should always be cleaned and tested.

I agree... No, it is not possible for a closed system, if working properly, to siphon water from outside the system. As the system builds pressure from starting the engine, to 195 degrees +/- at operating temperature, pressure builds from atmospheric to (X)psi. As it cools down after shut-down, the pressure is reduced relative to coolant temperature until it reaches atmospheric again. I'm sure there are some differential pressures between both sides of the pump's impellers, but with rubber hoses, and the remaining air in the recovery tank, there wouldn't be a negative pressure.

I agree again... unless the tank is new, they are thick plastic to endure the closed system's pressures, and are usually stained to the point of not being able to see the coolant level from outside the tank.

However, with all the different organic and hybrid coolants now, and the variations of corrosion inhibitors used, there are some that are clear. The G-05 made by Zerex I use for my Cummins is like this. Our late-80s system was designed for the old-fashioned green ethylene glycol. Unless you've added an aluminum head or some other performance part, there's no need to change from that.

 

What are you correcting? I didn't mention the boiling point. In a properly working Cherokee cooling system, straight water is not going to cause him overheating problems. He could have gone years with it like that and never had a heating problem.

The PO using straight or nearly straight water is the most reasonable explanation for his coolant being clear, or mostly clear.

 

Note from DJ to Tyler Smith
When you topped off the pressure bottle was the engine Cold or Hot and to which line did you fill it to MAX or MIN also with how much pre-mixed coolant.