Reconditioned Ford C-Max Turbo

1.6 TDCi reliable, 1.8 TDCi more fragile: two diesel engines, two very different turbo behaviours on the C-Max

The diesel C-Max is built around two engine families with distinct failure profiles. The 1.8 TDCi 115 (codes KKDA, KKDB, FFWA) is known to be more susceptible to variable-geometry fouling: the moving-vane turbine seizes up gradually, causing a loss of boost pressure, black smoke on cold starts and a marked reduction in load response. The 1.6 TDCi (codes HHJA, HHUB, HHDA, HHDB, DV6ATED4, MTDA, G8DA, G8DB, G8DC), available in 90, 101 and 110 hp, wears more slowly but is not without its faults: the CHRA, plain bearings and oil seals are the first components to suffer when oil changes have been stretched or the oil has been contaminated by fuel leaks at the injectors — a common issue on this generation of PSA-Ford engine.

References: a single 1.6 TDCi can cover several manufacturer part numbers

The sheer number of references is the main pitfall in this area. For the 1.6 TDCi alone, original Ford references span several successive revisions (prefixes 3M5Q-6K682, 4M5Q-6K682, 6G9Q-6K682, 7G9Q-6K682) along with the associated PSA equivalents (prefixes 9652443280, 9657530580, 9662371080, 9682881380…) depending on the power output and engine phase. The 1.8 TDCi uses its own references 6U3Q-6K682 and their equivalents. Cross-referencing the engine code stamped on the block with the original reference of the removed turbo remains the most reliable way to avoid a fitting error.

Address the root cause before replacing the turbo

Regardless of the engine, fitting a new turbo without first diagnosing the cause of the failure is a sure way to damage the replacement in short order. On the diesel C-Max, the recurring causes are fouling of the intake circuit by EGR gas recirculation, a blocked DPF creating excessive back-pressure at the turbine outlet, and disrupted oil supply due to a blocked filter or a faulty start-up valve. These points must be checked and rectified before any installation. All turbos listed here are new turbos.