RS4 Cooling System Failure: Fan Issues & Solutions

I had a similar issue with my 2018 RS5 last summer. With some experience working on cars, I can tell you that irregular engine cooling behavior needs immediate attention. In my case, the car radiator started showing the same symptoms, rising temperature gauge and the fan blade not spinning. Initially thought it was the fan motor, but after inspection, the workshop found a faulty speed sensor that wasnt sending correct signals to the cooling system controller. The repair included: Diagnostic testing of the cooling system, Replacing the defective speed sensor, Testing the fan blade operation, System recalibration Total cost was 250 Euro including parts and labor. The whole repair took about 3 hours. Before suggesting specific solutions, could you share: Any unusual sounds from the engine bay? Does the temperature rise mostly in traffic or also while driving? Have you noticed any coolant leaks? When was your last cooling system maintenance? These details would help determine if youre facing the same issue or if its something else in the temperature control system.

Last service completed at 71000KM. The unusual sounds are most noticeable during idle, with a slight grinding noise coming from the radiator fan area. The temperature rises mainly in stop-and-go traffic, but stays relatively stable during highway driving. No visible coolant leaks spotted, but the fan blade seems to spin inconsistently. Based on diagnostic testing at my local workshop, they found the radiator fan motor is drawing excessive current, suggesting bearing failure. This matches the grinding noise I mentioned. Getting a comprehensive quote for replacing both the fan motor and blade assembly since they recommend doing both at once for optimal engine cooling performance. My engine cooling issues seem different from yours, looks like I have a clear case of fan motor wear rather than a sensor problem. Would still appreciate any other experiences before proceeding with the repair.

Thanks for those extra details about your RS4. This definitely confirms my earlier suspicion about the fan assembly, but your symptoms point to a more serious issue than what I encountered with my sensor problem. The grinding noise and inconsistent fan blade movement are classic signs of a failing fan motor bearing. When I had my RS5 checked for engine cooling problems, the mechanic explained that these bearings often wear out gradually, causing exactly the symptoms you describe, especially that grinding sound during idle. A few notes on your situation: The workshop is right about replacing both components. The fan blade and motor work as a balanced unit for proper engine cooling, The stable temperature during highway driving makes sense since airflow helps cool the engine without relying on the fan, Car overheating mainly in traffic is typical of fan motor issues since thats when the fan needs to work hardest For reference, a complete fan assembly replacement on my RS5 (done about 6 months after my sensor issue) cost around 600 Euro. The repair took roughly 4 hours, but prevented more expensive engine damage that could have resulted from continued overheating. The fan noise will likely get worse if left unaddressed, so getting it fixed soon is a smart move.

Your car radiator and engine cooling issues do sound quite different from the previous responses. After the workshop diagnostic results, I feel more confident about proceeding with the fan motor replacement. The grinding noise during idle and inconsistent blade spinning match exactly what they found with the current draw test. The price quote I received is 750 Euro for both the fan motor and blade assembly, plus labor. While higher than I expected, its worth preventing potential engine damage from overheating. The workshop says the repair should take about 4-5 hours. Getting both components replaced makes sense since the cooling system needs to work as a complete unit. The fact that highway temperatures stay normal but rise in traffic confirms its likely the fan motor, as thats when the fan needs to work hardest. Will schedule the repair for next week and update the forum afterward with the final outcome and whether it resolved all the engine cooling issues. Thanks for sharing your experiences with similar temperature control problems, really helped confirm I was on the right track with the diagnosis.