Coolant pump failure
Major $900–$1,900All 981, more commonly at higher mileage.
The coolant pump fails and can shed impeller material into the cooling system. Caught early it is a routine part; caught late it means flushing debris out of everything downstream.
- Temperature climbing in traffic
- Coolant weeping at the pump
- Coolant loss with no obvious external leak
- Overheat warning under sustained load
Replace with the thermostat while the system is open. Many owners treat it as preventive at high mileage rather than waiting.