TIMING DRIVE Dodge Durango II рестайлинг

TIMING DRIVE

The primary timing chain is a single inverted tooth chain type. The primary chain drives the large 50 tooth idler sprocket directly from a 25 tooth crankshaft sprocket. Primary chain motion is controlled by a pivoting leaf spring tensioner arm and a fixed guide. The arm and the guide both use nylon plastic wear faces for low friction and long wear. The primary chain receives oil splash lubrication from the secondary chain drive and designed oil pump leakage. The idler sprocket assembly connects the primary chain drive, secondary chain drives, and the counterbalance shaft. The idler sprocket assembly consists of two integral 26 tooth sprockets a 50 tooth sprocket and a helical gear that is press-fit to the assembly. The spline joint for the 50 tooth sprocket is a non serviceable press fit anti rattle type. A spiral ring is installed on the outboard side of the 50 tooth sprocket to prevent spline disengagement. The idler sprocket assembly spins on a stationary idler shaft. The idler shaft is a light press-fit into the cylinder block. A large washer on the idler shaft bolt and the rear flange of the idler shaft are used to control sprocket thrust movement. Pressurized oil is routed through the center of the idler shaft to provide lubrication for the two bushings used in the idler sprocket assembly.

There are two secondary drive chains, both are roller type, one to drive the camshaft in each SOHC cylinder head. There are no shaft speed changes in the secondary chain drive system. Each secondary chain drives a 26 tooth cam sprocket directly from the 26 tooth sprocket on the idler sprocket assembly. A fixed chain guide and a hydraulic oil damped tensioner are used to maintain tension in each secondary chain system. The hydraulic tensioners for the secondary chain systems are fed pressurized oil from oil reservoir pockets in the block. Each tensioner incorporates a controlled leak path through a device known as a vent disc located in the nose of the piston to manage chain loads. Each tensioner also has a mechanical ratchet system that limits chain slack if the tensioner piston bleeds down after engine shut down. The tensioner arms and guides also utilize nylon wear faces for low friction and long wear. The secondary timing chains receive lubrication from a small orifice in the tensioners. This orifice is protected from clogging by a fine mesh screen which is located on the back of the hydraulic tensioners.

Scheme 152

Note. Components referred to as left hand or right hand are as viewed from the drivers position inside the vehicle.

Note. The blue link plates on the chains and the dots on the camshaft drive sprockets may not line up during the timing verification procedure. The blue link plates are lined up with the sprocket dots only when re-timing the complete timing drive. Once the timing drive is rotated blue link-to-dot alignment is no longer valid.

Engine base timing can be verified by the following procedure

Scheme 153

1. Remove the cylinder head covers. Refer to «REMOVAL»(ref-285333-S17676909062008052100000) .
2. Using a mirror, locate the TDC arrow (2) on the front cover (1). Rotate the crankshaft until the mark on the crankshaft damper is aligned with the TDC arrow on the front cover. The engine is now at TDC.
3. Note the location of the V6 mark (1) stamped into the camshaft drive gears. If the V6 mark on each camshaft drive gear is at the twelve o'clock position, the engine is at TDC on the exhaust stroke. If the V6 mark on each gear is at the six o'clock position, the engine is at TDC on the compression stroke.
4. If both of the camshaft drive gears are off in the same or opposite directions, the primary chain or both secondary chains are at fault. Refer to «CHAIN & SPROCKETS-TIMING»(ref-285333-S15724702862008052100000) .
5. If only one of the camshaft drive gears is off and the other is correct, the problem is confined to one secondary chain. Refer to «TIMING - SINGLE CAMSHAFT»(ref-285333-S26813086002008052100000) , in this procedure.
6. If both camshaft drive gear V6 marks are at the twelve o'clock or the six o'clock position the engine base timing is correct. Reinstall the cylinder head covers.

Scheme 154

1. Ensure that the engine is at TDC with both camshaft sprocket V6 marks (1) in the 12 o'clock position. 1 - COUNTERBALANCE SHAFT GEAR 2 - TIMING MARK 3 - IDLER SPROCKET GEAR
2. Look down the left cylinder head chain cavity. The timing dot on the counter balance shaft drive gear should be in the 6 o'clock position (2).

Scheme 155

Note. to adjust the timing on one camshaft, preform the following procedure.

Scheme 156

Scheme 157

Scheme 158

1. Using the Wedge Locking Tool 8379 (2), stabilize the secondary chain drive (3). For reference purposes, mark the chain-to-sprocket position.
2. Remove the camshaft drive gear retaining bolt. 1 - SPECIAL TOOL 8279 TIMING CHAIN WEDGE 2 - CAMSHAFT DRIVE GEAR 3 - RETAINING BOLT 4 - CYLINDER HEAD
3. Carefully remove the camshaft drive gear (2) from the camshaft.
4. Re-index the camshaft drive gear in the chain until the V6 mark is at the same position as the V6 mark on the opposite camshaft drive gear. 1 - Camshaft hole 2 - Special Tool 8428
5. Using Camshaft Holder 8428 (2), rotate the camshaft until the alignment dowel on the camshaft is aligned with the slot in the camshaft drive gear. CAUTION: Remove excess oil from camshaft sprocket retaining bolt before reinstalling bolt. Failure to do so may cause over tightening of the bolt, resulting in bolt failure. 1 - TORQUE WRENCH 2 - CAMSHAFT SPROCKET 3 - LEFT CYLINDER HEAD 4 - SPECIAL TOOL 6958 SPANNER WITH ADAPTER PINS 8346
6. Position the camshaft drive gear onto the camshaft, remove oil from bolt then install the retaining bolt. Using Spanner Wrench 6958 with Adapter Pins 8346 (4) and a suitable torque wrench (1), tighten retaining bolt to 122 N.m (90 ft. Lbs.).
7. Remove the Wedge Locking Tool 8379.
8. Rotate the crankshaft two full revolutions, then verify that the camshaft drive gear V6 marks are in fact aligned.
9. Install the cylinder head covers. See «INSTALLATION»(ref-285333-S18633069722008052100000) .