6.7 Adjustments Care and maintenance work This engine is equipped with an inter- nal exhaust gas return system. 6-cylinder: The exhaust valve opens briefly in the intake stroke. 8-cylinder: The exhaust valve opens briefly in the discharge stroke. Do not confuse this with the valve overlap! Engine TCD 2015 - 6 cylinder 6 Engine TCD 2015 -8 cylinder 41 Valve overlap set A1 B2 B3 A2 A3 B1 B2 A1 A2 B3 B1 A3 Valve overlap set A1 B3 B4 A3 A4 B2 B1 A2 B3 A1 A3 B4 B2 A4 A2 B1