Is it normal for coolant bottle to boil? - 1999 Dodge Durango

This expansion tank is only when coolant builds up so musch temperature and pressure that it needs to release, so it relieves itself from the radiator into the expansion tank.
Then, when coolant returns back to normal operating temperature, the pressurized air contracts, forming a negative pressure or vacuum, sucking the now-cooler coolant mix back in to the radiator and cooling system.
So if your water is not getting to the bottle at all, even when engine is boiling, check the outlet and overflow line for blockages, the stem-valve in the bottle is moving, pressure/water leaks in the cooling system venting water or steam.
Also check radiator cap is correct for the car model and operating.

If your radiator coolant is boiling then do not drive as your car could/will overheat and cause some serious damage

The temperature gauge in the Mk4 Golf is'nt that accurate, it will usually stay in the middle until you've got a major problem, where the coolant is boiling and expanding so if it's just slightly overheating, the gauge could show as normal.

The problem could be caused by numerous things such as a leak/crack in the coolant system and isn't pressurized such as a faulty coolant bottle cap not sealing properly, could be a problem with the fans, or and issue with the temp sensor /thermostat can cause confusion. It's hard to diagnose without seeing. I would take it into a garage for further inspection.

Mix new/ fresh coolant correctly, insure water pump is pressurizing system, ensure thermostat is opening, and then ensure that you have flow throughout your system.

Note: If you have a blown head gasket, your coolant may not actually be boiling, but releasing the compression from your cylinder(s) into your cooling system and blowing air out of your reservoir.

Your heater core is leaking anti-boil into the cabin. Either the core or the connections to the core are broken. CAUTION: Anti-boil is poisonous. Whenever working on the system take great care to keep it off your skin and do not allow it to puddle anywhere as dogs and cats are attracted to it as it has a sweet smell. Also, do not work on the system when it is hot as it can cause burns.

Drain anti-boil (wait until car is cool!!) and pull the core. It is located in the HVAC system, bottom right side. You will need to remove a substantial quantity of interior components to do this. Be prepared for some coolant spillage as you remove the core.

Using new hose clamps, install the new heater core, ensuring all connections are secure. Install any previously-removed interior/HVAC components or covers.

Refill the anti-boil through the overflow bottle, leaving the cap off. With the heater set to max heat, start the car, and allow to warm to normal operating temperature. Now slowly fill in the coolant to the specified level until the system is free from air bubbles. Install the cap.

Stop the engine and allow it to cool. Remove the cap slowly, allowing any residual air pressure to be released. Top up the anti-boil as needed, again leaving the cap off. Start the engine and allow it to warm to normal operating temperature. Top up anti-boil again, slowly to eliminate any air bubbles.

You may need to repeat this procedure two or three times until all air is purged from the system.

Its normal for the car to have antifreeze going to the overflow tank if thats what your asking.

do they go bad, that part is easy,
entropy happens , throughout the universe.
cars, x10000 (a mechanic is born, for this task)

my guess, is the car is boiling over, right?
post all symptoms and what size engine.

if boiling over.
try a new cap, on the radiator.
the overflow tank is for normal AF coolant expansion.
and the reverse actions. cooling and contraction.

over heating has only 2 causes, in the macro.
engine makes too much heat.
cooling system failures.
the mechanic has tools and tests that find out which one it is.
if not a hand on person, take it to any ASE rated shop.

an faulty thermostat will make the car boil but the water will normally go to the resevoir bottle. I be checking for burst radiator hose or cracked top tank before anything else. Thermostats are c;osed when the engine is cold and as the water heats up they open and allow water to pass through the radiator to cool. Coolant over the engine means boiling and escaping through an opening (hose,tank punctured radiator etc)

Hi and welcome to FixYa!

You may have a faulty radiator blower motor. If the blower blows weak it will surely be not enough to make the engine cooled down. One good reason the water boils on the bottle. Another issue can be a clogged radiator and a faulty water pump. These can make the engine hot too when faulty. Please give enough attention on the possible causes to prevent severe damage to the truck.

Hope this helps and thank you for using FixYa! Have a good one!

Sounds like a blown gasket. The pressure at combustion chamber varies from 75 in idle up to 150 in higher RPM. If the cylinder head gasket is blown, then gases are blown into the cooling system, increasing the pressure, the radiator cap pressure relief valve is open and coolant is discharged in the coolant bottle. In such cases it is common for the coolant bottle to boil. You can observe gases discharging in the bottle, mixed with coolant, from the cooling system. These are symptoms of a blown cylinder head gasket.
To find it out you have to perform cylinder compression test on your car. Start with a normal ("static") compression test. If you will find low or zero pressure in one cylinder this might be a bad ring, valve or cylinder head gasket
.

Hi,
Most likely it will cause overheating. The system uses pressure to raise the boiling of the coolant. Boiling coolant does not cool
well.