The valves are opened and closed directly by the four camshafts (see fig. 1)

fig. 1. Scheme of the valve drive mechanism: 1 - intake valves, 2 - exhaust camshaft, 3 - intake camshafts, 4 - exhaust camshaft, 5 - exhaust valves

The exhaust camshafts are driven by a toothed belt, while the intake camshafts are driven by gears on the exhaust camshafts.


Fig. 2. Camshafts: 1 - camshaft No. 2 (exhaust); 2 - gear; 3 - synchronization rotor; 4 - driven gear; 5 - camshaft No. 4 (exhaust); 6 - camshaft No. 3 (inlet); 7 - Camshaft #1 (Intake)

Camshafts (fig. 2) are made of cast iron alloy.

Due to the use of DIS (Direct Ignition System), a timing rotor is installed on the No. 4 camshaft to operate the camshaft position sensor.

The intake camshafts are driven by gears on the exhaust camshafts.

The gear train used to drive the exhaust camshaft provides mesh clearance adjustment and gear drive noise suppression.

Intake and exhaust valves and valve lifters

fig. 3. 1 - camshaft, 2 - shim, 3 - valve lifter, 4 - valve, 5 - shim, 6 - notch, 7 - valve lifter

Reduced valve stems are used to reduce inlet and outlet flow resistance (see Figure 3) and to reduce valve weight.

The shim is located directly on the valve lifter.

This design allows you to change the shim without removing the camshaft, which improves serviceability when adjusting valve clearance.

To improve serviceability when replacing shims, there is a cutout in the valve lifter.

There are 17 shim sizes available, in increments of 0.050 mm, ranging from 2.5 to 3.3 mm.

Timing timing belt

Fig. 4. Toothed timing belt: 1 - toothed pulleys of the mechanism, 2 - guide pulley No. 2; 3 - toothed timing belt, 4 - tensioner, 5 - guide pulley No. 1 (tension pulley)

The timing belt tooth configuration has been developed to reduce noise and enable power transmission at high load factors.

Timing belt tensioner

fig. 5. Timing belt tensioner: 1 - plunger spring, 2 - belt tensioner, 3 - return spring

The timing belt tensioner uses a spring and an oil damper to keep the timing belt under tension at all times.

Also, the timing belt tensioner performs the function of suppressing the noise produced by the timing belt.