Checking the tightness of the cooling system (BMW 5 Series E34)

Check for cracks by squeezing and bending the coolant hoses; replace hardened hoses.

The hoses must be pushed deep enough onto the fittings.

Check the tightness of the hose clamps.

Check the integrity of the radiator cap gasket and the expansion tank.

If the fluid level drops and it is impossible to find the leak, check the cooling system on a hot engine. To do this, warm up the engine and let it idle until the fan turns on. Check if the fluid is leaking around the water pump.

If the coolant leaks out of the lower hole of the water pump when the engine is hot, the cause is usually a broken seal. In this case, repair or replace the water pump.

However, it is quite difficult to find the leak location. In this case, it is recommended to perform a pressure test of the engine at a service station (special installation required). At the same time, the drain valve of the cover is also checked.