Triumph Stag Problems & Known Issues

The steering column top bearing on the Stag suffers from excessive wear, creating dangerous radial movement between the steering wheel and column shaft. MOT data shows this model fails at 242.4 times the fleet average for this specific defect. The worn bearing allows the steering wheel to move independently of the steering shaft, creating a serious safety hazard where steering input may not be transmitted to the wheels.

The Stag's alloy V8 engine is notoriously prone to overheating due to poor cooling system design and inadequate radiator capacity for the engine's heat output. The combination of alloy block and iron heads creates different thermal expansion rates that stress the head gaskets. Many surviving cars have been converted to Rover V8 engines to eliminate this fundamental design flaw. Original engines that haven't been rebuilt typically require significant cooling system upgrades to remain reliable.

The Stag V8 uses duplex timing chains that stretch with age and mileage, causing timing retardation and characteristic rattling from the timing case. Chain stretch affects valve timing and can lead to poor running, reduced power, and increased emissions. Worn timing chains and guides are a common issue on surviving original engines, particularly those that have experienced overheating episodes which accelerate chain wear.

The Stag's power steering system suffers from widespread pump and seal failures, with MOT data showing this model fails at 111.7 times the fleet average for power steering malfunctions. The hydraulic pump, pipes, and rack seals are particularly prone to leakage on these cars, often due to age-related deterioration of rubber seals and O-rings throughout the system.