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Camshaft drive

Camshaft drive



Upper illustration: version M99-00 to Vehicle Identification Number Y303999

Lower illustration: version M00 from Vehicle Identification Number Y304000 to M03

Camshafts with tappets

Each cylinder head has double overhead camshafts with large diameter on the base circle, which allows large lifting with small stress. All four camshafts are driven by a toothed belt with self-adjusting belt tensioner. Two adjuster rollers are also included in the belt circuit.

The camshafts work via hydraulic tappets directly on the valves. The hydraulic tappets are automatically adjusted in accordance with the longitudinal change of the valves at different temperatures. They operate in an oil-bath and are supplied with oil via an oil duct in the cylinder head. The main advantages with hydraulic tappets are a very quiet operation and very high operational reliability. In addition, each cylinder head has two air vent nozzles to prevent noise in the tappets after starting.

The valves have chrome-plated spindles and the exhaust valves are sodium-cooled. The camshaft sprockets on the rear cylinder head and the camshaft sprockets on the front cylinder head are interchangeable amongst themselves.

Belt tensioner

The belt tensioner located on the slack side of the toothed belt is dynamic and adjustable. After the belt tensioner has been adjusted in the belt tensions continuously and compensates for belt wear.

There are also two adjuster rollers in the belt circuit.