Older cars and trucks often had an overfill tank that would capture fluid that came out of the radiator when hot but was not truly a part of the system.
For this reason, older cars and trucks often had coolant topped off at the radiator, which is no longer the case.
The expansion and contraction is the reason to never open the radiator cap when the engine is hot since the coolant will be under pressure.
If the system is overfilled, the expansion of the coolant will cause the fluid to build up pressure, and fluid may cone out.
A radiator cap has a set pressure to hold coolant before it opens and lets the fluid blow out.
The set pressure of the radiator cap is a safety feature, so the coolant never has too much of a build-up of pressure.
If the coolant is overfilled, it will likely be blown out of the system by the radiator cap but usually does not damage any components.
Radiator fluid has a distinct smell often described as sweet which can often be smelled inside the vehicle.
Occasionally the radiator fluid can be blown into the electrical system, which may cause a problem, but this is rare.
The fluid should be between the two markers.
If the coolant is over the full marker, some fluid can be removed until it is at the correct level.
If there is no fluid or it is below the Low marker, some should be added.
If water only is added to a system, be sure to use distilled water as tap water has chemicals that can corrode the coolant system.
Only a small amount of water should be added to a coolant system. If it is very low, a 50/50 mixture of antifreeze should be used.
How to Add Coolant
- Locate the reservoir tank and the high and low markers.
- Using a 50/50 mixture of antifreeze, add it in until the fluid level is between High an Low markers.
A common quick way to remove the fluid is to use an old spray bottle where the top can screw off.
An old windshield cleaner bottle works well for this, but there are also other bottles that can also work well.
Alternatively, the bottom hose can be removed from the reservoir tank and fluid drained out.
If you accidentally overfill the coolant system in a vehicle, it may blow out when the engine comes hot.
There is usually no harm to this but more of a mess with antifreeze leaking out and a coolant smell.
While usually there is no harm, occasionally the antifreeze can blow into the electrical system and cause problems, although this is rare.
If you think the car or truck has too much coolant, it can be drained down to the correct levels.
An old spray bottle placed inside the reservoir is often used to remove excess fluid.
Have you had issues with overfilled coolant levels? Let us know your thoughts below.