Sounds like a blown head gasket
The amount of coolant it will take to fill your vehicle is dependent upon how low the coolant level is. You can add coolant to your coolant reservoir. The reservoir will have an indicator of when the coolant system is full.
The plastic coolant reservoir on the fender feeds directly into the coolant system. Just add coolant to the reservoir and if you have drained the coolant or otherwise emptied the system, you may need to check the level in the reservoir after running the engine, or more accurately, after the engine has cooled. Once the coolant level has stabilized, just check it periodically to make certain that the coolant level never gets too low.
It replaces coolant back into the system by drawing coolant from the reservoir that was pushed out into the reservoir during the heat up process.
Start by taking the top off of the coolant overflow reservoir. To bleed the system, run the 1998 VW 2.0 Beetle about 10 minutes, then check the coolant level. Add coolant if needed, then replace the reservoir top.
Clean the reservoir and flush the cooling system.
You don't add coolant directly to the radiator, rather it goes into an overflow reservoir in the engine compartment. There will be a "min" or "max" line (or both) showing the proper level to be maintained. The reason we do not remove the radiator cap anymore is to keep the coolant system a sealed system so that no air can penetrate the coolant systems. By adding coolant through the reservoir (which has liquid in it already which is drawn from the bottom of that reservoir) we are not comprising the sealed system.
There is no cap on the radiator; instead, the coolant reservoir is pressurized along with the rest of the cooling system. Look on the passenger side, under the hood. You should see the windshield washer reservoir AND the coolant reservoir. Be careful with the lid of the coolant reservoir. If the engine is hot, it will blow off in your face.
Don't! Most cars have a reservoir for radiator coolant ... add liquid to the reservoir. Opening the radiator cap introduces air into the sealed system ... you don't want air bubbles in the cooling system.
The radiator does not have a cap, instead, the coolant system reservoir is also pressurized and the pressure cap is on the reservoir.
it is normal, when the coolant is hot and pressure built, the pressure cap allows the coolant to drain to reservoir to reduce pressure in the cooling system But, if it continually does this whereby the reservoir overflows and the vehicle overheats due to a lack of coolant actually in the radiator when cool, there may be an overheating problem or blown head gasket on the engine.
In the engine compartment, on the left side of the engine is the coolant reservoir. In the coolant reservoir, there is a sensor at the bottom of the reservoir. This sensor is supposed to let you know when you are low on coolant, but can also become defective, and give you a "false-positive" reading. The only way to know this is to check your coolant when the low coolant light comes on. If there is a significant decrease in coolant, you may have a problem in the cooling system , but if you don't, chances are the sensor isn't working. If the sensor is the problem, you can unplug it from the coolant reservoir, by unscrewing the two screws holding the reservoir to the car's inside firewall, then tilting the back of the coolant reservoir forward until you see wiring coming from the bottom of the reservoir, which is the plug for the low coolant sensor. Unplug the sensor, and the low coolant light won't come on anymore. However, you will now have to make sure you check your coolant level in the reservoir on a regular basis.
You should add coolant with the engine off and cool, top off the radiator and fill the coolant reservoir to the cool or cold level. When the system is hot or running it will be pressurized and will be dangerous to open. You can however add coolant to the overflow reservoir at any time.