boiling coolant?

T-bird Tim

Registered User
The coolant in my reservoir boils when I turn the car off. The temp gauge never gets above the "m" in the normal temp range; and thats at 60 mph with the a/c on. Weather has been in the low 100s with low humidity. I flushed the system last week and am running mostly water with water wetter and a small amount of coolant. No water in the oil and the car runs fine. Just want see if this is common or is it a symtom of a problem. Thanks
 
running mostly water is going to make it boil much easier, i say you need more coolant and you may still have air pockets in the system since you just flushed it.
 
Vote number one for Head Gaskets..... Boiling in the overflow bottle is a symptom. It depends on where it pops at as to if you get water in your oil or not right away...
 
Ok so I'll add more coolant and perge the system. If that doesnt work, I will add some headgasket repair stuff to the coolant. A mechanic I talked to here swears by that stuff. Thanks guys.
 
i would stay away from hg repair, if its leaking, then sooner or later you will have to fix it, its not going away especially on these motors.
Im not going to say its hg yet either.
 
think about this...

While you are running the engine, the coolant is moving through it, absorbing heat and taking it away. When you shut the engine off, it is still HOT and still GENERATING HEAT for a while...But there is no coolant being pumped through to take any of that heat away. All engines get hooter right after shut down. I think you are seeing a normal behavior as the coolant expands and leaves the radiator for the recovery jug. I say this for a number of reasons:

1. You are running in the normal operating range when running and this would/should be when you would see a HG problem. The engine is OFF, why would you have head gasket problem then???

2. The boiling point of a given liquid increases as the pressure in the system increases. That's why they use a pressure cap. While water will boil at 212*, that same water doesn't boil till it hits about 240* under 16lbs of pressure. Water at or above 212* in the recovery jug is NOT under pressure and should boil.

3. While water wetter is great stuff and works as designed, it does not alter the boiling point of plain water. What it does do is affect/interupt the surface tension of the water allowing it to make better contact with the metal surfaces to absorb and carry away more heat faster.

I think you are experiencing normal behavior for the circumstances. What most people fail to realize is the bubbles, or percolation they see in the recovery jug with a bad HG is not because it's hot, but because combustion pressure is escaping the chamber and going into the cooling system. Think blowing into a straw in a glass of liquid.
 
If you haven't already done so I would also consider replacing the thermostat with a 180 degree unit while flushing the system also. They help quiet a bit on keeping the engine coolant cooler than the stock 192 units.

Also boiling coolant is a bad sign no matter how you spread it. I'd remix your coolant mixture, make sure the fan is kicking on and all the other tests you can do on these cars to verify you don't overheat and blow a gasket. If you do all the above and still have coolant boiling you have bigger problems and you know what those are.

-Tim
 
Adding coolant won't increase the resistance to boiling. But what it does have is anti-corrosion additives that keep the water from corroding the inside of your heads, water pump and radiator and heater core.

Never run with less than 30% antifreeze unless you add some other type of corrosion inhibitor.

Coolant doesn't go into the recovery container until it starts cooling down. Usually it won't be at 212 when it does that, but I suppose it's possible. I'd try to find a way to verify engine temp as water boiling simply means over 212. If it's going into recover at over 220, that's probably not a good thing as engine temp must have been quite high that "cooler" is 220.
 
I read on several sites to use distilled water, water wetter and about 15% coolant. Mine never runs above half on the guage, ac on, hot days, city or highway.
I live down south where cold isn't an issue, but may bump it up to 30% after checking my freeze protection.
 
This afternoon I checked the cap; seals look good and the spring works as it should. I still may replace it though. I purged the air from the system, there was alot in there. Still getting some bubbles but not nearly as bad. Watched the coolant tank closely as the car got to operating temperature. It worked as it should with the cooland level going up in the tank as the temp rose. Once the car cooled off the coolant level went back down to where it should be. I dont think it's the headgaskets so much as just air in the system.
 
My two cents:

The stock gauge is not a good judge of temp.

Water "cools" the best but boils easily especially when the operating temp is 200-220+. You have an undersized brass radiator, you run the AC and you live in texas, no doubt your boiling over.

Add some orange prestone to the mix as it increases your boiling point, it says so on the back of the bottle.
 
I would start with the radiator cap. If you've ever tried to remove the cap when it's hot you'll notice the rush of bubbles into the reservoir. A slow leaking cap has the same effect.
 
While not looking to bash...

Adding coolant won't increase the resistance to boiling. But what it does have is anti-corrosion additives that keep the water from corroding the inside of your heads, water pump and radiator and heater core.

Never run with less than 30% antifreeze unless you add some other type of corrosion inhibitor.

Coolant doesn't go into the recovery container until it starts cooling down. Usually it won't be at 212 when it does that, but I suppose it's possible. I'd try to find a way to verify engine temp as water boiling simply means over 212. If it's going into recover at over 220, that's probably not a good thing as engine temp must have been quite high that "cooler" is 220.

I can find no other way than to say this is misinformation!

First of all, corrosion inhibitors are not the only reason for using antifreeze. The most important feature is the chemical composition prevents freezing at temps way below where water freezes. Water boils at 212*F at sea level, while anti freeze boils at around 230*F at sea level. By mixing it and water and putting it under pressure we can get to almost 270* F before boil.

So antifreeze does increase boil over protection.

Pressure increases boiling point. The formula is about 3* per pound.

Second, the flow of coolant into and out of the recovery tank and radiator are not as you indicated here. As the coolant heats up it expands. as it expands, it takes up more space. If it has no more space to take up, it builds pressure as it expands. Once the expansion pressure overcomes the cap's pressure, the cap lifts and the coolant enters the expansion/recovery tank. After engine shut down, the coolant cools and shrinks. As it shrinks, it creates negative pressure, or vacuum. This draws the coolant back into the radiator from the expansion tank. The bottom line is the coolant moves from the radiator to the recovery tank as it gets hotter, not colder and moves from the recovery tant to the radiator as it gets cooler.

If the water in his radiator is 220* when it goes into the expansion tank, it WILL boil because it has exceeded its boiling point and is no longer under pressure.

While, not being there to see this with my own eyes, I think he is experiencing normal behavior for the conditions stated and people are going to have him throwing parts and money at a problem that doesn't exist.

This can be tested easily enough by draining and flushing the system and putting the correct mix of water/antifreeze. My money says he will no longer see boiling in the recovery tank.
 
That being said, A new radiator cap costs less than a gallon of antifreeze . So start cheap and work your way up.;)
 
I can find no other way than to say this is misinformation!

First of all, corrosion inhibitors are not the only reason for using antifreeze. The most important feature is the chemical composition prevents freezing at temps way below where water freezes. Water boils at 212*F at sea level, while anti freeze boils at around 230*F at sea level. By mixing it and water and putting it under pressure we can get to almost 270* F before boil.

So antifreeze does increase boil over protection.

Pressure increases boiling point. The formula is about 3* per pound.

Second, the flow of coolant into and out of the recovery tank and radiator are not as you indicated here. As the coolant heats up it expands. as it expands, it takes up more space. If it has no more space to take up, it builds pressure as it expands. Once the expansion pressure overcomes the cap's pressure, the cap lifts and the coolant enters the expansion/recovery tank. After engine shut down, the coolant cools and shrinks. As it shrinks, it creates negative pressure, or vacuum. This draws the coolant back into the radiator from the expansion tank. The bottom line is the coolant moves from the radiator to the recovery tank as it gets hotter, not colder and moves from the recovery tant to the radiator as it gets cooler.

If the water in his radiator is 220* when it goes into the expansion tank, it WILL boil because it has exceeded its boiling point and is no longer under pressure.

While, not being there to see this with my own eyes, I think he is experiencing normal behavior for the conditions stated and people are going to have him throwing parts and money at a problem that doesn't exist.

This can be tested easily enough by draining and flushing the system and putting the correct mix of water/antifreeze. My money says he will no longer see boiling in the recovery tank.

Funny, in another thread I tried saying the same thing but was blown off as an idiot. I gave up as its their car, not mine.

Oh well.
 
I got a 92 that had a blown head gasket and it would make bubbles in the coolant tank a few minutes after starting her up.....
 
If you do flush your coolant, please try to use distilled water along with your coolant. Pure distilled water doesn't boil on it's own, unless it has other contaminants in it. So it really helps preventing boiling and steam pockets. And it's better to use because it won't introduce minerals etc.

One of the best $1 or $2 mods you can find! ;)
 
If you do flush your coolant, please try to use distilled water along with your coolant. Pure distilled water doesn't boil on it's own, unless it has other contaminants in it. So it really helps preventing boiling and steam pockets. And it's better to use because it won't introduce minerals etc.

One of the best $1 or $2 mods you can find! ;)

Water that doesn't boil? :eek: Sweet!

The reason for using distilled water in a cooling system is to help avoid build-ups and deposits when it DOES boil, evaporate, or whatever else. Distilled water is distilled so it shouldn't have near the contaminants (minerals) that tap water would have (ie: limestone, calcium, iron, etc.) but it WILL boil. It's still water after all!

Also, I believe all coolant changes are supposed to be with distilled water (and whatever antifreeze) - I've never read anything recommending tap water for a coolant change. Distilled saves from buildups and corosion, maybe not prevent, but it does help.
 
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