Hey, what is the best way to check your antifreeze level in a car in the overflow tank? Running/not running, warm/cold, etc. You get the point. thanks.

Depending on the vehicle, the simplest way is to just look at the overflow tank and see exactly where the water level is in reference to the cold or hot level lines. It doesn't matter whether the vehicle is running or not, but rather whether the water temperature is hot to the touch or cold.

There's this thing call "thermal expansion coeficient" for everything, whether it be solid, liquid or gas. Everything expands and contracts at different rates and most expand when heated and contract when cold. Water however, is one of those rare things that expands when it's heated AND expands when it's cold. At a boiling temperature of 212 degrees fahrenheit, water vaporizes into steam. As it cools, it contracts and reduces in volume because it gets more dense. 40 gallons of water at 45 degrees fahrenheit heated to 145 degrees will expand to 41 gallons, an internationally accepted ratio of 40:1. Once the water cools to 39.2 degrees fahrenheit, it has reached it's maximum density and it's volume is at its minimum. As the temperature continues to drop, it begins to expand once again. At 32 degrees it begins to freeze and will continue to expand as it gets colder. I've seen what happens to an engine block that had just water, no antifreeze in it after a severe cold spell. Sure, the freeze plugs did their job and popped out, but the cast iron block cracked in several places.

Sorry, I got carried away...

Anyhow, years ago you'd pop your radiator cap once the engine was cold to check the water/antifreeze level. Nowadays, the hot/cold level lines on the expansion tank is your guide. As the engine heats up the water/antifreeze, the water expands and once the pressure in the cooling system gets high enough (15 psi for example), the radiator cap will allow the now expanded hot water to overflow into the bottom of the overflow tank. Once the engine is off and the water begins to cool it creates a vacuum which draws fluid from the bottom of the overflow back into the engine cooling system. Because it's being drawn from the bottom of the overflow tank, there's no way air can be drawn back in, thus a sealed system.

But, here's the problems I've found. A cracked hose between the radiator cap and overflow tank will allow air to be drawn back into the cooling system, now less coolant to keep the engine cool on those really hot, stop-and-go traffic days. A cracked tank holds no liquids. A dirty tank can look like it's at the right fluid level, but it can actually be bone dry, so I make it a habit to pop the cap on the overflow tank to make sure the fluid level is right. Also, if the fluid inside the tank looks dirty or cruddy, something might not be right. A friend of mine recently went to have his radiator flushed out at a local garage and they found engine oil in the expansion tank. Long story short, his $100.00 flush turned into an additional $800.00 to replace his head gasket.

In the spring and just as winter starts around here this is what I do. With the engine off and cold I remove the radiator cap and take a good look at it. You can flip it over and push down on the inner seal with your thumbs and it should move but take some good pressure. Make sure that the water level in the radiator is right at the cap, full. If it's not, it's been sucking air back into the cooling system somehow, there's a leak somewhere and needs attention. Look at the water/antifreeze and see that it looks good, not dirty, etc. Replace the radiator cap tightly. Pop the cap and look inside the overflow tank. It should be at the COLD level or somewhere thereabouts and fluid clean. If you have to add much fluid, you should use a 50/50 mix of water and the correct antifreeze. If the tank itself is dirty, take the time to remove it, scrub it out and refill it with clean 50/50 mix to the proper level. Don't worry about the fact that you have now "unsealed" the sealed cooling system because the next time you use the vehicle, any air will be purged into the overflow tank and fluid drawn back into the system.

Didn't mean to get carried away... Hope this helps.



Pup

[QUOTE]Originally posted by HEMI-PUP:
Water however, is one of those rare things that expands when it's heated AND expands when it's cold.



Pup[

So it always expands? Or it contracts when it's cold?

Water from boiling contracts as it cools and reaches maximum density at 39.2 degrees fahrenheit, reaching it's smallest volume. Then it begins to expand once again as the temperature continues to drop below 39.2 degrees. It starts freezing at 32 degrees and the colder it gets, the more it expands.

Pup

Cool. That pretty much covers all of it I think...hehe. I am always up for new info though.

QUESTION For the last few days right after I turn the truck on, I can hear a gurgeling, bubbling noise in the dash area, sound like air trapped in the lines, this is with the a/c on or off and eventually goes away after running the truck for a while. What the heck is it. My overflow tank is at full and when I popped the cap on the radiator is was full

Sounds like AC to me. Not sure though. If it only does it once or twice, I guess don't worry about it. If the AC works fine too. Not sure though. As long as the carpet isn't getting wet.

quote:

I can hear a gurgeling, bubbling noise in the dash area

Did Freeze send you his gerbil.

Well the A/C went out, good call GrapHemi

Goin to the Dealership Wade? LOL.. Damn! You are using your AC? I know around here we use ac on the days when the air is really damn on cold days, the ac, when on, goes throgh the dry charger and gets rid of the extra moisture and helps to clear the windows faster.

quote:

Originally posted by Superjay:

quote:

I can hear a gurgeling, bubbling noise in the dash area

Did Freeze send you his gerbil.

Nope. You've got mail!

quote:

You've got mail!

You've got male.

quote:

Originally posted by Superjay:

quote:

You've got mail!

You've got male.

Look anything like this?

I would eat my underwear to be 18 again.

These must be yours then,.. someone at DT had them...