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Old 02-10-2017, 12:57 PM   #1
Charlie-III
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Default Nuts and Bolts...... cooling systems and coolant, what and why

So, what is a cooling system and why do we use coolant, not straight water?

The cooling system does a couple things:
-Removes heat from inside the engine keeping a fairly constant temperature for good performance and not "killing" parts.
-Removes internal heat so you don't "cook the oil" (although oil needs to get over ~212*F/100*C to remove condensation) since the oil not only lubricates, it also removes heat, just from different spots.
-It's a source of heat for inside the car when the temperature is low outside.

Typical cooling systems in automotive use use a 50/50 water coolant mix. This is for consideration of freezing, boiling, water pump lubrication (mostly the seals) and corrosion protection ("dissimilar metal corrosion" or "Galvanic corrosion").
These systems are also "closed systems" (different from a "sealed system") compared to much older cars which were normally "open systems" that dumped expanded coolant onto the ground instead of an expansion tank.
A common closed system has an expansion tank/overflow tank to allow for the coolant expansion. From what I've seen, the expansion of coolant from ~32*F/0*C to ~210*F/100*C is ~1/16 of the volume with a 50/50 mix. I base this on the systems I typically use have 2 gallons of coolant and the normal volume change in the expansion tank is ~1 pint.
Thus, when the coolant heats up, it expands and has to go somewhere. It goes into the expansion tank when hot and is siphoned back into the system when it cools maintaining a proper amount in the system.
If you keep the expansion tank properly filled, you should basically NEVER get low on coolant in the rest of the system. Exceptions are if the water pump fails, break a hose, leaks in the system or a failed headgasket.

Some expansion info can be found here....
Another link.....

Older systems still had a radiator cap & overflow tube/hose, but it just dumped on the ground as the coolant expanded due to heat. Since the systems were of a lower pressure and the engines typically were not as stressed and carried more coolant, it was not an issue. You just needed to top off the radiator itself as needed.

Newer cars with smaller systems (partly to reduce weight), emissions considerations, aerodynamics & the environment (dumping toxic coolant on the ground is not good for nature) the designs went to closed systems.

Pretty much any fluid has a higher boiling point with increased pressure, thus with today's cooling systems, getting air into it can cause issues as air (and most gases) expands a LOT more with the same temp rise compared to a 50/50 coolant mix.
This can force more coolant out leading to more "air" in the system reducing pressure even more.
Additionally, a gas tends to have a lower rate of heat transfer than coolant which also leads to overheating.
Having a "full system" and a correct radiator cap (pressure wise) allows the system to build pressure as the coolant heats & expands.
This additional pressure raises the coolant boiling point a fair amount.
Thus, if you don't have a "full system" or the radiator cap spring/seal is failing, you have a higher tendency to overheat the coolant forcing it out.:frown2:

Some general info about pressure....
Relevant excerpt...

Water will boil at 212*F but when we put it under pressure we can raise the boiling point by three degrees F for every pound per square inch of pressure. Therefore a 15 PSI cap (fairly normal) will increase the boiling point to 257*F from 212*F.

We want temperatures around 200*F and we want pressures around 15 PSI.


So, we have an idea on WHY we have a closed system and WHY we use coolant, but what about the water?

The performance difference between distilled, de-ionized & tap water is almost not worth checking. But the life of the parts that contact the coolant is important & based on the water used.
Most tap water has minerals in it which tend to "stick" to surfaces, worse when heat is applied. This coating (can be iron, calcium, lime, etc.) acts like an insulator, meaning it won't transfer heat as well which goes against the cooling systems job of removing heat.

Some more coolant/water can be found here.......

The coolant itself "loses usefulness" over time/miles, thus you can start to have cooling issues. Some of the coolant life is "time" but mostly "miles", a coolant replacement every couple years helps maintain it's effectiveness.

A good look at the coolant should show one of the following:
-Almost a fluorescent green (pretty common) & clear
-Almost a fluorescent yellow (may look like a pale green) & clear
-Almost a florescent red (kinda like fresh ATF) & clear

Clear means nothing in the coolant like rust, particles, oil, globs of "who knows what", flakes, etc.

link to a similar webpage.....

Some nice general info.....
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Old 02-10-2017, 12:57 PM   #2
Charlie-III
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Coolant types, can you mix them?

I will add as I find info, but here are some excerpts from Internet sites...

That dealer discovered something else that may be useful to you: When our water pump was changed by a (non-GM) mechanic for us a short time earlier, he mixed regular (green) antifreeze with the remnants of the pink DexCool coolant already in the engine. The two coolants will form a kind of "antifreeze Jello" when they are mixed. and it will clog (or partially clog) your radiator & heater core. Flushing your system only once may not rid you of this gelatinous mess, flushing it 3 or maybe even 4 times ought to clear it out.

Never, NEVER mix coolants!!! -Mixing DexCool and the Green Ethylene Glycol turns into JELLO!! & kills the radiator attached your 5.3, some dealers will claim they can flush it all out, but my personal experience proves such flushing DOES NOT clean it out as such dealers may claim. Mixing coolants WILL require a new radiator & thermostat (along with the heads, head gaskets, or engine, if they also need replacement)

In general........ (I have seen various colors called out, but....)

Blue, green & yellow can mix together (sorta known as a "toxic coolant", inorganic ethylene glycol)

Red, pink & orange can mix together (sorta known as a "safe coolant", Organic Acid Technology [OAT} or propylene glycol)

There are universal "mix with anything" coolants out there. I have no direct experience on how true that is.

When in doubt, or you want to change types, you should REALLY FLUSH THE SYSTEM with fresh water. Draining what was in there, filling with water (distilled or de-ionized), burping, running until warm with interior heat on, draining and then fill with water & coolant should be fine.
More than one flush fill may be required though.

Where can coolant go?

-Hose leaks
-Hose clamp leaks (I usually replace OEM "spring clamps" after a few years to stop this issue, I use SS wormdrive clamps)
-Radiator and/or heater core leaks (helps to spray water through the radiator while washing the car to reduce salt corrosion that will rot the aluminum away...)
-Gasket/seal leaks (head gaskets, water pumps, thermostat housing, etc.)
-Old radiator cap that has a bad seal or weak spring. Helps to test their pressure now & then.
-A little bit due to water evaporation from the expansion tank (usually very slow rate though).

As stated, keeping an eye on the level in the overflow tank can give you a heads up on "system leak condition". You may not see leaks, but the tank level will drop if you have issues starting.

I have an old "Stant cooling system pressure checker" that I use along with adapters for the newer "small" radiators & caps. You can use it on a cold system (so you don't get burned) to watch pressure drop and/or to find leaks.
A clean engine can help find leaks since the coolant will show easier on a clean surface than a dirty/oily surface.
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Old 02-10-2017, 12:57 PM   #3
Charlie-III
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Another save.......

I mentioned a cooling system pressure tester. When I bought mine, there was only one type of cap, a large 1/4 turn type. Now, there are dozens. There are 1/4 turn in various sizes and various sizes of multi turn screw on.
This makes testing problematic trying to keep all the adaptor sizes around, but I have info on our system to help out.

First off, the basic tester. You can get from multiple sources, but I will stick to Amazon.
I have a Stant brand although there are a couple others that look identical, these come in a plastic case.
Stant, PN 12270
https://smile.amazon.com/Stant-12270...ure+tester+kit

With that, you need the 32mm radiator adaptor PN 12027
https://smile.amazon.com/Stant-12027...DF533J8F5S4EJP

Also the 32mm radiator cap adaptor PN 12021
https://smile.amazon.com/Stant-12021...M80DADC0NTFXPK

Now you can test the system and cap. This works for all years AFAIK. The 32mm is the ID of the radiator neck with the cap removed, double check before buying. There are also 31mm caps for other cars, so check.

An additional benefit, you can check for HG leaks from the cylinder to the cooling system.
With a cold/cool system, remove the radiator cap, install the tester and adaptor, add a few pounds of pressure (5-10) and start the car.
Now we wait and watch. As the coolant heats up and the thermostat opens, the pressure will rise slowly. This is normal. What we're looking for is a fast and high pressure increase if the HG is blown and the combustion pressure is going into the cooling system.
You can vent some pressure from the tester, but if it tries to peg the gauge repeatedly, suspect a HG issue.

There you have it. Ask questions if need be,

Last edited by Charlie-III; 03-25-2017 at 06:24 PM.
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Old 02-10-2017, 01:39 PM   #4
vladd
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Cool story bro
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Old 02-10-2017, 02:09 PM   #5
SoapBox
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You're having quite the day...

All good info for everyone, of course...but if you want to make technical threads, you should post them in the correct or at least relevant technical or maintenance forum.

This thread, in an engine forum, and the thread thread () in the wheel and tire.
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Old 02-10-2017, 02:16 PM   #6
Charlie-III
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Quote:
Originally Posted by SoapBox View Post
You're having quite the day...

All good info for everyone, of course...but if you want to make technical threads, you should post them in the correct or at least relevant technical or maintenance forum.

This thread, in an engine forum, and the thread thread () in the wheel and tire.
LOL..... copying my threads from another car forum I'm on. We keep these in the "newbie section" there since we have some separation of engine types.

Forum staff can move as needed, but I felt this was a good spot.

Not quite "Unabomber" level, but worthwhile.
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Old 03-25-2017, 06:25 PM   #7
Charlie-III
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Added info in post 3.
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Old 01-12-2018, 08:52 PM   #8
Captain Eric
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I have a occasional wiff of coolant. I've had to replace the radiator and hoses, but I used the original clamps and original caps. Is it prudent to replace the clamps, and how can I test the caps?
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Old 01-12-2018, 11:40 PM   #9
Charlie-III
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Quote:
Originally Posted by Captain Eric View Post
I have a occasional wiff of coolant. I've had to replace the radiator and hoses, but I used the original clamps and original caps. Is it prudent to replace the clamps, and how can I test the caps?
If they are just spring clamps, then they lose tension over time. I prefer SS worm drive clamps.
Testing caps, you need,a cooling system pressure tester with a cap adaptor, as I listed in a previous post here.
For most peeps, it's cheaper to just replace caps now and then instead of buying the test equipment.
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