Valve Mechanism General

► Each cylinder of this engine has 2 intake valves and 2 exhaust valves. Intake and exhaust efficiency is increased due to the larger total port areas.

► This engine uses roller rocker arms with built-in needle bearings. This reduces the friction that occurs between the cams and the areas (roller rocker arms) that push the valves down, thus improving fuel economy.

► A hydraulic lash adjuster, which maintains a constant zero valve clearance through the use of oil pressure and spring force, is used.

► The intake camshafts are driven by the crankshaft via the primary timing chain. The exhaust camshafts are driven by the intake camshaft of the respective bank via the secondary timing chain.

► This engine uses a dual VVT-i (Variable Valve Timing-intelligent) system, which controls the intake and exhaust camshafts to provide optimal valve timing according to driving conditions. With this adoption, lower fuel consumption, higher engine performance, and fewer exhaust emissions have been achieved. For details of dual VVT-i control, refer to page EG-121.

Intake Camshafts

Timin (Prim;

Intake Camshafts

Timin (Prim;

Roller Rocker Arm

Valve Guide Bush

Hydraulic Lash Adjuster

285EG18

Timing Chain (Secondary)

Do It Yourself Car Diagnosis

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