1. B58 Coolant Leaks — Expansion Tank & Water Pump
Symptoms: Coolant loss without visible external leaks, engine overheating, warning lights, low coolant level message.
Typical Mileage: 40,000–80,000 miles.
Repair Cost: £500–£1,500 [PLACEHOLDER] (expansion tank, water pump, or coolant lines replacement).
Replacement Cost: N/A — repair only (if caught early; ignored coolant loss can cause overheating and engine damage).
Urgency: Check — book inspection urgently if coolant loss or overheating occurs.
Our recommendation:
The B58 is a robust engine, but coolant leaks from the expansion tank, water pump, and plastic fittings are a common issue. The B58's water pump is driven by the serpentine belt and can fail. If the expansion tank or water pump develops a leak, the engine can overheat rapidly. A £500–£1,500 cooling system repair is far cheaper than the consequences of a warped head or blown head gasket. Regular inspection of coolant levels is essential.


