Volkswagen EA113

The petrol four that carried the Volkswagen Group through the Mk4 era, and the origin of the 1.8T twenty-valve turbo — five valves per cylinder, a small turbocharger, and the engine that put forced induction into ordinary Golfs, Passats, A4s and Leons. Later members moved to direct injection as the 2.0 FSI and the first 2.0 TFSI.

Sludge is the defining failure and it is a maintenance failure, not a design one. The 1.8T's oil passages and turbocharger feed are intolerant of extended intervals and the wrong oil, and a sludged engine kills its own turbocharger by starving the bearing. On any 1.8T of unknown history, oil-change evidence is a diagnostic input, and fitting a turbocharger without establishing why the last one died repeats the failure.

The direct-injected 2.0 FSI and TFSI members add the two faults that generation is known for: cam-follower wear on the high-pressure fuel pump, which can destroy the camshaft lobe if left, and intake-valve carbon. Check which injection system is fitted before assuming either applies.