Diesel engine with a working volume of 1.9 liters (VW Polo 4)

The camshaft mounted on the cylinder head drives 8 vertically arranged valves via hydraulic plate tappets. The camshaft is driven by a toothed belt from the engine crankshaft. The clearances in the drives of the respective valves are automatically compensated by the hydraulic plate tappets. This eliminates the need for clearance adjustment as part of maintenance.

SDI diesel engine: the high-pressure fuel pump (HPFP) of the distributor type is flanged on the side of the cylinder block and driven by a toothed belt. SDI — Supercharged Diesel with Direct Injection — a diesel engine without supercharging and direct mixture formation.

PD-TDI diesel engine: diesel fuel is injected via unit injectors. For this purpose, a unit injector is installed on each cylinder, combining a plunger pair of the fuel pump, a metering valve and a fuel injection nozzle. Fuel is supplied by a booster pump located in the fuel tank and a twin pump flanged to the cylinder head and driven by the camshaft. The diesel engine with unit injectors is also equipped with a turbocharger. PD — Pumpe-Diise-Einspritzszstem — injection system with unit injectors; TDI — Turbodiesel-Direkt-lnjection — a diesel engine with gas turbine supercharging and direct mixture formation.