Camshaft Timing Chain
| ITEM | DESCRIPTION |
|---|---|
| 1 | Intake camshaft |
| 2 | Variable Camshaft Timing (VCT) actuator - Intake |
| 3 | Secondary timing chain |
| 4 | Secondary timing chain guide |
| 5 | VCT actuator - Exhaust |
| 6 | Exhaust camshaft |
| 7 | Secondary timing chain tensioner guide |
| 8 | Secondary timing chain tensioner |
| 9 | Primary timing chain tensioner |
| 10 | Primary timing chain tensioner guide |
| 11 | Crankshaft |
| 12 | Primary timing chain guide |
| 13 | Primary timing chain |
| 14 | Idler sprocket |
| 15 | Secondary timing chain guide |
There are 2 bushed timing chains used to drive the camshafts through an intermediate idler sprocket. The primary camshaft chain is driven by a sprocket on the rear of the crankshaft which drives the idler sprocket. The secondary camshaft chain is driven by the idler sprocket and then passed over the sprockets on the intake and exhaust camshafts. The camshaft sprockets are integrated with the Variable Camshaft Timing (VCT) actuator assemblies.
The primary timing chain has an installed timing chain guide which is secured to the cylinder block. A chain tensioner is installed to the primary timing chain tensioner guide. The timing chain tensioner guide rotates on a pivot bolt. The primary timing chain is a hydraulic/mechanical tensioner operated by spring tension to apply a controlled tension to the timing chain.
The primary timing chain tensioner receives pressurized engine oil from the variable flow oil pump with integral vacuum pump. The primary timing chain tensioner incorporates a ratchet mechanism to make sure that chain tension is not lost when the engine is not running.
The secondary timing chain has 2 installed timing chain guides. The left timing guide is installed on the cylinder head and the upper timing guide is installed to the camshaft carrier. The secondary timing chain is a hydraulic/mechanical tensioner operated by spring tension to apply a controlled tension to the timing chain. The secondary timing chain tensioner receives pressurized engine oil from the variable flow oil pump with integral vacuum pump. The secondary timing chain tensioner incorporates a ratchet mechanism to make sure that chain tension is not lost when the engine is not running.
The tensioners maintain the timing chains at the correct tension and allow for and dampens backlash in the chain tension due to engine deceleration. The timing chains and tensioners are maintenance free components.
Use the procedure and special tools to make sure that the correct crankshaft to camshaft timing is correct. Both the primary and secondary timing chains have gold colored links which are aligned with timing marks on the sprockets.