1. Open the hood and inspect the underhood space. When inspecting the engine, pay attention to the presence of coolant in the expansion tank, the integrity of the rubber hoses, radiator...
2. ...and thermostat housing.
Helpful Hint: A burst hose can be temporarily repaired using duct tape.
Reinforced adhesive tape is especially well suited for this purpose (for example, silver color), which can be purchased at auto stores.
If coolant leaks from under the thermostat housing, tighten its mounting bolts. If tightening the bolts does not eliminate the leak, it must be removed, the mating surfaces must be cleaned and installed using Loctite 518 sealant or its equivalent.
[Material taken from an online portal www.Renaultbook.ru]
Helpful Hint: If you detect a leak in any of the hoses where it connects to the pipe, drain the coolant (see "Replacing the coolant"). Squeeze the clamp with pliers and slide it along the axis of the hose.
Remove the hose from the branch pipe. As a rule, the cause of the leak is corrosion of the sealing surface of the branch pipes. Clean the damaged surface and install the hose on the sealant. After the sealant dries, fill in the coolant.
3. Inspect the hose connections to the cover and thermostat housing...
4. ...and also with the heater radiator pipes. If coolant leaks, replace the hose clamps.
Possible malfunctions of the cooling system, their causes and methods of elimination
| Cause of malfunction | Method of elimination |
| The engine gets very hot | |
| Low coolant level in the expansion tank | Top up the coolant |
| Thermostat is faulty (the valve is stuck in the closed position) | Replace Thermostat |
| The water pump is faulty | Check the pump and replace if faulty |
| The radiator core is clogged with dirt and insects | Wash the outside of the radiator core |
| Radiator pipes, hoses and engine cooling jacket are clogged with scale and silt deposits | Flush the cooling system and fill with fresh coolant |
| The electric fan does not turn on due to a break in the electrical circuits or failure of the sensor, relay or fan motor | Check and repair electrical circuits. Replace sensor, relay or electric fan assembly as needed |
| Damage to the valve in the expansion tank cap (is constantly open, which is why the system is under atmospheric pressure) | Replace the expansion tank cap |
| Engine Overheats, Cold Air Comes Out of Heater | |
| Excessive loss of coolant level due to leakage or damage to the cylinder head gasket, which causes vapor lock in the engine water jacket | Fix coolant leak. Replace damaged cylinder head gasket |
| The engine takes a long time to warm up to operating temperature, the thermal regime during movement is unstable | |
| Thermostat is faulty (the valve is stuck in the open position) | Replace Thermostat |
| Constant decrease in coolant level in the expansion tank | |
| Radiator leaking | Replace the radiator |
| The expansion tank is leaking | Replace the expansion tank |
| Coolant leaks through leaky connections of pipes and hoses | Tighten the hose clamps |
| The water pump seal is damaged | Install the water pump with sealant |
| The cylinder head mounting bolts are not sufficiently tightened (during prolonged parking on a cold engine, coolant leaks at the junction of the block head with the cylinder block; in addition, traces of coolant may appear in the engine oil) | Tighten the cylinder head mounting bolts to the specified torque |
| Coolant leak through the cylinder block water jacket plugs | Replace the damaged gasket, restore the tightness of the plugs |
| The heating radiator is leaking | Replace the heating radiator |