The timing chain death rattle
Earlier turbo Mini engines are famous for timing chain and tensioner wear, known in the Mini community as the death rattle: a diesel-like clatter on cold start. Ignored, it ends with a jumped or snapped chain and a ruined engine. Any used turbo Mini from that era should be bought with proof the chain and tensioner were addressed, or priced as if they were not.
Carbon buildup and misfires
Like their BMW siblings, direct-injection Mini engines carbon up the intake valves over time, causing rough idle and misfires, and the turbo models can also be hard on ignition coils and plugs. A Mini that stumbles at idle usually is not broken. It is dirty, and walnut blasting plus fresh ignition parts typically wakes it right up.
Cooling system leaks
Thermostat housings and water pumps on these cars are common leak points, often made of plastic that gets brittle with heat. In a Texas summer, a marginal cooling system does not stay marginal for long. Coolant smell or a dropping level is a fix-it-now item on a Mini.
Clutch and suspension wear
Minis get driven the way they were designed to be driven, which is enthusiastically. Clutches, control arm bushings and strut mounts wear accordingly. On a test drive, feel for a high or slipping clutch engagement point and listen for clunks over bumps. Neither is a dealbreaker, but both belong in the price negotiation.