Camshaft Drive System

The four overhead camshafts are driven by three separate 8 mm (0.315 in), single-row, fine pitch chains. The primary drive chain connects the crankshaft with both large intake camshaft sprockets, the balance shaft sprocket and the intermediate shaft sprocket. The exhaust camshafts are driven by short chains from the intake camshafts. Primary timing chain tension is held by a tensioner that hydraulically applies pressure to a pivoting tensioner shoe/chain guide. The hydraulic tensioner minimizes chain noise and provides accurate valve action by keeping slack out of the chain and continuously adjusting for chain wear. As the chain stretches from wear, a ratchet mechanism inside the tensioner prevents the nylon pad from retracting when the engine is turned off and engine oil pressure ceases. The intake to exhaust camshaft chain tensioner contains an internal spring that provides a constant load on the secondary timing chains.