Flush the Radiator Coolant?

This comes up all the time here. For a recent thread, see

The "answer" to your question depends on what type and year vehicle you have, and what kind of coolant it uses. Currently there appear to be several different types, which may or may not be mutually compatible. It is a good policy to use the correct fluid, and replace it as necessary, if you can find out what and how often that is.

Earle

Jeep recommends every 3 years or 30K miles.

Dave

On consumer vehicles with no filters, now that cooling systems really are almost hermetically sealed, yes. What happens is small amounts of combustion gas and casting swarf invariably get in the system and stay there.

Even if you can't do a proper flush, drop a lower hose and drain out what you can and refill with the right juice. Use exactly what the manufacturer says, especially if you can't totally flush the system.

Brian Foster did pass the time by typing:

It won't hurt, but you don't need to flush the system. Just properly drain and refill. Generally if you keep an eye on the fluid mix there isn't much you should have to do but add a bit more water or antifreeze as it's needed.

My ZJ has over 120K and the coolant has been exchanged about four times. It's still nice and green.

Black coolant indicates that either the block is cracked or someone put the wrong type in there and it reacted. There are two types of antifreeze out there and they do not mix.

Hi Doug:

There are more than 2 types of coolant. In fact, coolant is getting more confusing every year it seems.

Just off the top of my head I can think of: 4 (I'm sure there are more)

-"regular green" type

- DexCool orange

- Mopar orange (which is not compatible with DexCool) -Prestone makes a "universal coolant" which is supposed to be compatible with "any" coolant.

I don't believe that the Prestone "universal" is really universal, but that's just me.

Tom

We went over this before. The "good stuff" from Prestone comes in a black container now. On

want the black jug, black cap, labelled "Heavy Duty Antifreeze/Coolant".Notice that it contains "A blend of ethylene glycol and a speciallyformulated inhibitor package designed for heavy duty cooling systemapplications." Make sure that you read that, before actually buying it. Donot take the sales person's word, he will say anything. Earle

Yep every two years and check the PH with some test strips

There is another method where you check the voltage at the coolant. Usually either 0.05 volts or 0.10 volts relative to ground is considered borderline. You put your voltmeter on the appropriate scale, touch the battery negative terminal with the negative probe, and stick the positive probe in the coolant. If there is appreciable voltage, then current is flowing and metal is being removed from one place (where you want it) and deposited in another place (where you don't want it). J. C. Whitney used to sell (and probably still does) a radiator cap with a "sacrificial electrode" in it. The idea is that the electrode is a reactive metal that is dissolved before the cooling system or engine metals. It is probably better to change the coolant as needed, by whatever method, than to rely on something like this.

Of course, chemical companies don't really want you to know when it is time to change the fluid, any more than they want you to get maximum use out of your motor oil. They are happy with once every two years, 30k miles, or whatever interval you use. On the other hand, if you are draining out "bad" fluid, then it has already done some damage.

Earle

No swimming pool I live by the Chesapeake Bay we used PH strips when I was a deck plate engineer in the Coast Guard. I have found that even the 5 yr so called long life gets real acidic at two years but the freeze/boil over remain good. I also have the HVAC mechanics that work for me use them to check the closed loop glychol chiller systems.

Coasty

Yep, that is why all ships use zincs on their hulls they go before the ship hull does. Coasty

Coasty did pass the time by typing:

That and a spool of strip material is real cheap. Cheaper than a new radiator core. :)

I have never changed the coolant in any car I've ever owned. The car body rusts away or the car dies from other causes. And I've owned cars 25 years and longer.

Fred