Replacing a car radiator - how it's done!

If the engine temperature consistently exceeds the ideal level, keeping the engine dangerously close to boiling point, it is important to find the cause as soon as possible. Postponing this will inevitably burn the head gasket. Read this guide on how to control your car's radiator when your engine is overheating before it's too late.

Operating temperature matters

The engine must reach its working temperature as quickly as possible and keep it at a constant level in order to function normally. The main reason lies in the properties of the heated metal. All metal engine parts expand when heated. . Temperatures caused by internal friction and combustion in particular are very high.

Therefore, all engine components inevitably expand . In order to avoid jamming of a warm engine, all parts in a cold state have a certain clearance. This gap provides the so-called sliding fit once the parts have optimally expanded at operating temperature. If the engine is cooled too much, causing it to stay below operating temperature, internal wear will occur sooner. Therefore, adequate temperature control is necessary so that the engine can quickly reach operating temperature and maintain it at a constant level.

Vehicle cooling circuit

A liquid-cooled vehicle has two connected cooling circuits. A small circuit circulates coolant through the engine and a small piece of hose outside the engine, allowing the engine to reach operating temperature as quickly as possible.

The large cooling circuit includes a radiator as well as an expansion tank. The connection or valve between the two cooling circuits is the thermostat, which is located at the junction of the three hoses. The thermostat is an automatic valve that opens or closes depending on the temperature of the coolant.

Stages of car cooling:

The engine is cold → small cooling circuit active → engine not cooling

Engine reaches operating temperature → thermostat opens → car radiator lowers coolant temperature

Engine temperature reaches high coolant limit → the car radiator fan turns on.

Engine temperature exceeds operating temperature → check if the engine indicator light is on.

Engine temperature continues to rise → the expansion tank bursts, the coolant hose bursts, the pressure reducing valve opens ( depending on the car brand )

The car continues to move → the plungers jam in the cylinder, the cylinder head gasket burns out - the engine is destroyed, the car stands still.

If the warning signals of the engine are ignored for too long, it will eventually collapse.

We are looking for the cause of the engine overheating

Engine overheating can have three causes:
- the engine is losing coolant
– Faulty cooling circuit.
– insufficient cooling capacity

Loss of coolant occurs through leaks . Leakage can occur both externally and internally. The leak to the outside is easy to find: just follow the entire refrigeration circuit. Brightly colored antifreeze will show the damaged area .

If there is a constant shortage of coolant but no leak is found, the cylinder head gasket may be damaged. This will be seen in the constant white exhaust and excess internal pressure in the cooling circuit. The sweetish smell of antifreeze in the cabin indicates a malfunction of the interior heating system.

Circulation may be interrupted faulty thermostat, clogged cooling circuit, or faulty water pump . Thermostats may gradually stop functioning. Luckily, replacing them is very easy. Diagnosing a clogged circuit is difficult. Typically, the only option is phased replacement of all hoses and pipelines . The water pump should always be replaced in accordance with the maintenance schedule. This is a wear part with a certain service life.

The cause of poor cooling is usually a faulty car radiator, which should be quite obvious:
– the radiator is damaged and dented
- the radiator is heavily rusted
– cooling lamellas (lamellas) fall out.

If the car radiator is seriously damaged, it should be replaced as soon as possible. For safety reasons, the thermostat is also replaced and the cooling circuit is thoroughly flushed.

Car radiator replacement

Replacing a car radiator isn't difficult, and the parts aren't as expensive as you might think. They are cheap enough to justify buying them as a new part. Do-it-yourself solutions with used radiators from a landfill are not recommended.

1. Coolant drain Open the cap of the expansion tank or car radiator. The coolant drains through the radiator. There is a drain plug at the bottom. Water is collected in a bucket. Carefully inspect the coolant.

2. Checking the coolant If the coolant is dirty brown and cloudy , it is contaminated with oil. The likely cause is a defective cylinder head gasket or a damaged valve. If the coolant is rusty , then an insufficient amount of antifreeze was filled. Antifreeze has a strong anti-corrosion function. In this case, the cooling system should be flushed until the water used for flushing is clear. Simply connect a garden hose to your car's radiator hose. Corrosion must be completely removed from the circuit to prevent further problems. In the event of rust in the coolant, the water pump and thermostat are also replaced.

3. Removing the fan Removing the car radiator is much easier if the fan has been removed first. It is secured next to the radiator with four to eight bolts and is easily accessible, although the lower bolts can only be accessed under the vehicle.

4. Dismantling the car radiator The heatsink is secured with a few available screws. Dismantling the radiator should not last longer than half an hour. Always be careful not to damage the mounting brackets . They are very difficult to repair.

5. Installing a new car radiator If rust is found in the cooling circuit, it is recommended that, in addition to flushing, a thorough treatment with a cooling circuit cleaner be carried out. Now you can install the radiator. The fan is also installed and the cooling circuit is filled with water.  Be sure to always use the correct antifreeze. The use of unsuitable antifreeze can damage gaskets and hoses!After installing the car radiator and fan and filling the circuit with coolant, the system must be vented.

6. Bleeding the cooling circuit To bleed air from the cooling circuit, start the engine with the expansion tank open and add water until the level is constant. Depending on the type of vehicle, additional measures may be required. To properly ventilate the cooling system, you should always know the requirements of the specific vehicle type.

7. Checking the cooling systemThe cooling system is now being tested. The refrigeration circuit works adequately when the operating temperature rises quickly and is maintained at the optimum level. When operating temperature is reached, let the vehicle idle until the fan kicks in. Don't wait for the cylinder head to burn out. If the fan does not turn on at the maximum allowable operating temperature, turn off the engine and allow it to cool. Subsequently, the fan needs to be inspected and repaired.

Safe driving with a healthy cooling circuit

A healthy cooling circuit, timely maintenance greatly contributes to safe driving. There is nothing more distracting than having to constantly monitor the operating temperature. In the case of an automotive radiator replacement, careful action is required for a reliable solution. A new water pump, thermostat and fresh coolant make the car fit for years of carefree driving. .