Recurring Audi S8 Coolant Issues Despite Recent Repairs

Had similar problems with my 2017 Audi S6. The recurring coolant issues pointed to multiple potential problems in the cooling system. First, checked the radiator hoses for visible leaks or cracks, none found. The radiator fluid level kept dropping though, even after recent refills. After thorough inspection, the issue turned out to be a faulty water pump combined with a degraded radiator cap that wasnt maintaining proper pressure. A few warning signs to check on your S8: Look for coolant puddles under the car, Listen for unusual whining noise from the water pump area, Watch if the cooling fan runs constantly, Check if the radiator hoses feel too soft or too hard when cool This was a serious repair requiring water pump replacement along with new radiator hoses since the old ones showed internal deterioration. Given your vehicle is newer, first have the radiator cap pressure tested, its often overlooked but can cause similar symptoms when failing. Best to get this checked soon since chronic coolant loss can lead to engine overheating. While some checks can be done at home, the pressurized cooling system requires proper diagnostic equipment to pinpoint the exact issue.

Thanks for sharing your experience. Dealing with the same problem on my S8 right now. When the radiator fluid started leaking again after the first repair, I also discovered air pockets in the system. The water pump ended up being the main culprit, but the radiator cap was also not sealing properly. Did the repair cost include both the water pump and hoses replacement? Would be helpful to know the total cost to budget accordingly. Also curious if you had any other cooling system problems since getting it fixed?

Good to hear you found the root cause. My repair costs were much simpler than yours, the mechanic discovered the cooling fan was not activating properly due to a faulty cable connection near the coolant reservoir. The fix only cost 95 Euro for reconnecting and securing the wiring. Since having this electrical issue resolved last week, the coolant level has remained stable with no more low fluid warnings. No signs of air pockets or leaks from the water pump either. These symptoms can sometimes be misleading, what appears as a major cooling system failure might just be a minor electrical fault preventing proper component operation. For your case though, with confirmed issues in both the water pump and radiator cap, you are looking at a more extensive repair. Definitely get those air pockets properly bled out when they do the work. A compromised water pump combined with trapped air can cause serious engine overheating if left unchecked.

Following the repairs in my S8, wanted to share an update. Took it to the mechanic yesterday and spent about 780 Euro for the complete fix. They replaced the water pump, installed new radiator hoses, and put in a fresh radiator cap. The mechanic also found some minor corrosion in the coolant reservoir which they cleaned out. The whole job took about 5 hours. They pressure tested the entire cooling system after repairs and properly bled out all air pockets. Got a 2-year warranty on the new water pump, which gives some peace of mind. The engine temperature now stays perfectly stable and the coolant level hasnt budged since the repair. Definitely glad I addressed this before risking any engine overheating issues. Would recommend anyone with similar symptoms to get it checked right away rather than waiting like I did initially.