What Causes the Water Temperature to Rise When Braking?
2 Answers
It might be an issue with the thermostat; try replacing it. The problem could also lie with the thermostat or the water pump—when braking, the pressure in the radiator might cause the thermostat to close or the water pump to stop working. This situation could also be due to a short circuit in the wiring. Therefore, it's recommended to visit a repair shop to inspect the wiring harness, especially focusing on the engine compartment wiring harness, to check if poor grounding is the cause. Here are some additional notes: Caution: Keeping the car in D gear while braking for a long time can cause the transmission fluid temperature to rise very quickly. Since the transmission fluid is cooled in the radiator (there is a partition between the coolant and the transmission fluid), heat conduction can lead to an increase in water temperature. It's advisable to use P gear when parking for extended periods.
I've been repairing cars for twenty years and often encounter owners complaining about a sudden rise in coolant temperature when braking. This usually happens because after the vehicle slows down or stops due to braking, the cooling fan in front of the engine isn't working, causing a sharp drop in cooling efficiency. If your fan is electric and its plug is loose or the fuse is blown, the radiator can't cool the heat generated by the engine. Another possible cause is a thermostat stuck in the closed position—while driving normally, airflow might barely manage heat dissipation, but when braking and airflow stops, the issue becomes apparent. Also, check if the water pump is faulty—if it fails, coolant can't circulate to the radiator, and when you brake to a stop, the temperature spikes. I recommend stopping immediately to check if the fan is running. Don't wait until the engine overheats and starts smoking—that could lead to serious damage.
