2. Faulty thermostat: Even after installing a new thermostat, it's possible that it may be faulty. A defective thermostat might not open or close properly, which would disrupt the proper flow of coolant. Ensure that the thermostat is installed correctly and test it to verify its functionality.
3. Clogged radiator: Over time, the radiator can become clogged with debris such as dirt, rust, and scale. This can obstruct the flow of coolant through the radiator, leading to a hot upper radiator hose and cold lower hose. Try flushing the radiator with a suitable radiator flush to remove any blockages.
4. Faulty radiator cap: A malfunctioning radiator cap can affect the pressure within the cooling system. A faulty cap can cause the system to lose pressure, resulting in a lower boiling point for the coolant. This could cause the upper hose to stay hot while the lower hose stays cool. Replace the radiator cap if necessary.
5. Issues with the heater core or heater control valve: If there is no heat in the dash after replacing the water pump and thermostat, it's possible that there's a problem with the heater core or heater control valve. These components play a crucial role in directing warm coolant into the vehicle's cabin for heating. Check the condition of the heater core and control valve and address any issues as needed.
