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Timing Components

Engine, Cooling and Exhaust › Engine
Unified entry — merged from multiple cross-listed pages in the original manual.
Procedures
Timing Components: Service and Repair17 steps
△ CAUTION
The 3.7L is a non free-wheeling design engine. Therefore, correct engine timing is critical.
ℹ NOTE
Components referred to as left hand or right hand are as viewed from the drivers position inside the vehicle.
ℹ 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 Once the timing drive is rotated blue link-to-dot alignment is no longer valid.
ℹ NOTE
To adjust the timing on one camshaft, preform the following procedure.
△ CAUTION
Remove excess oil from camshaft sprocket retaining bolt before reinstalling bolt. Failure to do so may cause over-torquing of bolt resulting in bolt failure.
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  1. Remove the cylinder head covers (See cylinder head cover section).
  2. Using a mirror, locate the TDC arrow on the front cover. Rotate the crankshaft until the mark on the crankshaft damper (2) is aligned with the TDC arrow on the front cover (2). The engine is now at TDC.
  3. Note the location of the V6 mark stamped into the camshaft drive gears (1,2). 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. See Timing Chain and Sprockets procedure.
  5. If only one of the camshaft drive gears is off and the other is correct, the problem is confined to one secondary chain. See Single camshaft timing, 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. COUNTER BALANCE SHAFT TIMING
  7. Ensure that the engine is at TDC with both camshaft sprocket V6 marks in the 12 o'clock position.
  8. Look down the left cylinder head chain cavity. The timing dot (2) on the counter balance shaft drive gear should be in the 6 o'clock position. TIMING - SINGLE CAMSHAFT
  9. Using the Wedge Locking Tool (2), stabilize the secondary chain drive. For reference purposes, mark the chain-to-sprocket position.
  10. Remove the camshaft drive gear retaining bolt (3).
  11. Carefully remove the camshaft drive gear from the camshaft.
  12. 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 (1,2).
  13. Using the Camshaft Holder , rotate the camshaft until the alignment dowel on the camshaft is aligned with the slot in the camshaft drive gear.
  14. Position the camshaft drive gear onto the camshaft, remove oil from bolt then install the retaining bolt. Using Special Tools, Spanner Wrench with Adapter Pins and a suitable torque wrench, tighten the retaining bolt to 122 Nm (90 ft. lbs.)
  15. Remove the Wedge Locking Tool.
  16. Rotate the crankshaft two full revolutions, then verify that the camshaft drive gear V6 marks are in fact aligned.
  17. Install the cylinder head coversCylinder Head Cover(s) - Installation.
Valve Timing - Descriptionreference
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DESCRIPTION The timing drive system (Figure 1)has been designed to provide quiet performance and reliability to support a non-free wheeling engine. Specifically the intake valves are non-free wheeling and can be easily damaged with forceful engine rotation if camshaft-to-crankshaft timing is incorrect. The timing drive system consists of a primary chain (6), two secondary timing chain drives (1,4) and a counterbalance shaft drive.
Factory service manual
From the 2008 KK factory manual — descriptions, specs, torque & procedures for this part.
TIMING DRIVE📷 1
1 - RIGHT CAMSHAFT SPROCKET AND SECONDARY CHAIN 2 - SECONDARY TIMING CHAIN TENSIONER (LEFT AND RIGHT SIDE NOT
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INTERCHANGEABLE)📷 1
3 - SECONDARY TENSIONER ARM 4 - LEFT CAMSHAFT SPROCKET AND SECONDARY CHAIN 5 - CHAIN GUIDE (LEFT AND RIGHT SIDE ARE NOT INTERCHANGEABLE) 6 - PRIMARY CHAIN 7 - IDLER SPROCKET
8 - CRANKSHAFT SPROCKET 9 - PRIMARY CHAIN TENSIONER
The timing drive system has been designed to provide quiet performance and reliability to support a non-free wheeling engine. Specifically the intake valves are non-free wheeling and can be easily damaged with forceful engine rotation if camshaft-to-crankshaft timing is incorrect. The timing drive system consists of a primary chain (6), two secondary timing chain drives (1,4) and a counterbalance shaft drive. See Fig. 169.
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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. 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.
TIMING VERIFICATION📷 2
1 - TIMING CHAIN COVER 2 - CRANKSHAFT TIMING MARKS
CAUTION: The 3.7L is a non free-wheeling design engine. Therefore, correct engine timing is critical.
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:
1. Remove the cylinder head covers. 2. Using a mirror, locate the TDC arrow on the front cover. Rotate the crankshaft until the mark on the crankshaft damper (2) is aligned with the TDC arrow on the front cover (2). The engine is now at TDC. See Fig. 171.
1 - LEFT CYLINDER HEAD 2 - RIGHT CYLINDER HEAD
3. Note the location of the V6 mark stamped into the camshaft drive gears (1,2). 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. See Fig. 172. 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 AND SPROCKETS-TIMING. 5. If only one of the camshaft drive gears is off and the other is correct, the problem is confined to one
secondary chain. 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.
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TIMING - SINGLE CAMSHAFT📷 2
1 - CYLINDER HEAD 2 - SPECIAL TOOL 8379 3 - TIMING CHAIN
NOTE: to adjust the timing on one camshaft, preform the following procedure.
1. Using the Wedge Locking Tool 8379 (2), stabilize the secondary chain drive. For reference purposes, mark the chain-to-sprocket position. See Fig. 174.
1 - SPECIAL TOOL 8379 TIMING CHAIN WEDGE 2 - CAMSHAFT DRIVE GEAR 3 - RETAINING BOLT 4 - CYLINDER HEAD
2. Remove the camshaft drive gear retaining bolt (3). See Fig. 175. 3. Carefully remove the camshaft drive gear from the camshaft.
1 - LEFT CYLINDER HEAD 2 - RIGHT CYLINDER HEAD
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 (1,2). See Fig. 176. 5. Using the Camshaft Holder 8428, 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-torqueing of bolt resulting in bolt failure.
6. Position the camshaft drive gear onto the camshaft, remove oil from bolt then install the retaining bolt. Using Special Tools, Spanner Wrench 6958 with Adapter Pins 8346 and a suitable torque wrench, Tighten the 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.
SHAFT-BALANCE
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IDLER SHAFT
1. Remove the primary and secondary timing chains and sprockets. Refer to CHAIN AND SPROCKETS-
TIMING.
NOTE: To remove the idler shaft, it is necessary to tap threads into the shaft, to install the removal tool.
2. Using a 12 mm X 1.75 tap, cut threads in the idler shaft center bore. 3. Cover the radiator core with a suitable cover.
CAUTION: Use care when removing the idler shaft, Do not strike the radiator cooling fins with the slide hammer.
4. Using Slide Hammer 8517 remove the idler shaft.
IDLER SHAFT
1. Thoroughly clean the idler shaft bore. 2. Position the idler shaft in the bore.
NOTE: The two lubrication holes in the idler shaft do not require any special alignment.
NOTE: Before using the retaining bolt to install the idler shaft, coat the threads and the pilot on the idler shaft, with clean engine oil.
3. Using the primary idler sprocket retaining bolt and washer, carefully draw the idler shaft into the bore until fully seated. 4. Coat the idler shaft with clean engine oil. 5. Install the timing chains and sprockets. Refer to CHAIN AND SPROCKETS-TIMING.
CHAIN AND SPROCKETS-TIMING