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Questions about cooling system


I wanted to check the condition of the coolant but the overflow tank seemed pretty dry and removing the radiator cap I couldn’t take up anything either.

So I figured I would top off both with some distilled water. I maybe put about ~300ml?

Now removing the radiator cap again after it wasn’t hot to touch I still can’t see any coolant in there to suck up to inspect and in the overflow tank it’s still just the deionized water I put earlier.

So… what should I do. It’s expected to go only around 6 degrees celcius so hopefully nothing will freeze. Originally I believe it was a 50/50 mix so I’m sure only 300ml won’t cause freeze.

FYI when I filled the rad car was off, poured until it wouldn’t go down, started the car, sucked up some water, re-poured until it would’t go down to much and then filled the overflow.

Sounds like you have a coolant leak. Hopefully it isn’t between the water jacket and a cylinder.
I commend you for using distilled water. But the system also needs coolant. First, however, I’d recommend you get the system pressure tested.
Post the results.

Ah damn ok.

But I think I may not have fully filled the rad either.

I noticed top of overflow tank there is a tube that goes down and is not connected to anything. I guess that it if there is to much liquid expanding and just dumps out?

That’s correct. However, there’s also a “hot” and a “cold” lines molded into the reservoir. These are fill lines.

The way the system works, when the engine gets hot the expanding coolant is released to the reservoir when the pressure exceeds the rating of the radiator cap.
Then, when the engine is shut off and the coolant contracts as it cools, coolant is drawn back into the engine from the reservoir. Everything from the engine to the coolant in the reservoir should be coolant. The only air should be in the reservoir above the coolant.

I still think you should get this properly diagnosed and corrected. The coolant should not have gotten this low.

I would try a new radiator cap first, 300 ml in the radiator is pretty minimal, 1.2 cups, the water in the reservoir could be subject to freezing, but I doubt it had much of an effect in the cooling system, depending on how much coolant is left. Get some of the proper mix of the proper coolant to use going ahead.

Don’t run with diluted coolant too long. You don’t have the full amount rust prevention that a fresh 50/50 mix gives. Rusting inside the engine, best avoided.

hyundai tucson

I was going to check bulletins for you. Is this a fairly new vehicle?

Please state the Model-Year and approximate miles/kilometers on this vehicle.

Yeah… just don’t wanna mix coolants you know. I will probablY flush the rad and that should give me an idea of the color.

Sorry! I thought I put it in. 195 000KM

It’s a 2006.

But whatever water was in the rad mixed with the rest so I do have ok freezing and boil protection. It’s just what is by itself in the overflow tank right that I should take out for now.

I noticed my expansion tank never really mixed? Does this only rarely happen?

You have a significant cooling system problem. Take to a shop and have it tested. Overheating can cause engine damage.

The car runs fine never overheated, never passed the middle temp gauge mark.

I think you guys are a bit over panicking. There is probably only a small leak and when I did fill the radiator it wasn’t done properly/long enough, thus why it’s still not full.

Just keep adding 50/50 mix to the radiator until it stops taking it. Add 100% coolant to the reservoir to get it to 50/50.

Rarely, yes. Whenever there is an opening (leak, either external or internal) in a “closed loop” cooling system there’s a good chance the coolant will “expand” and vent to the point of least resistance (which is normally the expansion tank).

Also, since the system could be compromised, the vacuum necessary to draw coolant back into the radiator will not exist.

I wouldn’t operate this vehicle until a competent mechanic/technician checks out the cooling system to see if or where the problem(s) is/are. It hasn’t overheated, yet, but it could soon.

Please note that the temperature gauge could give false reading if air is trapped in the system.

This could be a minor problem about to go major. It’s better to be safe than sorry.

We can’t see the car, and your car had no coolant in the overflow and nothing visible in the radiator. That’s a big problem. Get it checked.

I’ll fill everything up and then see if there is an issue.

Do you know if there is any special procedure for your make/model/engine? Some vehicles are fussy. Do you have a cooling system bleeder valve at the high point of the system?

Better now than after the engine overheats.