Chain And Sprockets, Timing: Removal
The magnetic timing wheels (1) must not come in contact with magnets (pickup tools, trays, etc.) or any other strong magnetic field. This will destroy the timing wheels ability to correctly relay camshaft position to the camshaft position sensor.
When the timing chains are removed and the cylinder heads are still installed, DO NOT rotate the camshafts or crankshaft without first locating the proper crankshaft position. Failure to do so will result in valve or piston damage.
The Variable Valve Timing (VVT) assemblies (Phasers) and Oil Control Valves (OCVs) can be serviced without removing the engine timing cover. Refer to ASSEMBLY, VARIABLE VALVE TIMING, PHASER / OIL CONTROL VALVE, REMOVAL .
- Disconnect and isolate the negative battery cable.
- Remove both cylinder head covers. Refer to COVER(S), CYLINDER HEAD, REMOVAL .
- Remove the spark plugs. Refer to SPARK PLUG, REMOVAL .
- Raise and support the vehicle. Refer to HOISTING, STANDARD PROCEDURE .
- Drain the cooling system. Refer to DRAINING .
- If removing the oil pump chain or primary chain, remove the oil pan. Refer to PAN, OIL, REMOVAL .
- Remove the engine timing cover. Refer to
.NOTE:
Take this opportunity to measure timing chain wear. Refer to MEASURING TIMING CHAIN WEAR .
CAUTION:When aligning timing marks, always rotate engine by turning the crankshaft. Failure to do so will result in valve or piston damage.
- Rotate the crankshaft clockwise (as viewed from the front) to place the number one cylinder piston at top-dead-center on the exhaust stroke by aligning the dimple (7) on the crankshaft with the block/bearing cap junction (6).
- While maintaining this alignment, verify that the ARROWS
(4) on the left side cam phasers point toward each other and are parallel to the cylinder head cover mounting surface (3) and that the right side cam phaser ARROWS
(5) point away from each other and the SCRIBE LINES
(1) are parallel to the cylinder head cover mounting surface (2).NOTE:
The phaser markings (1 and 3) could align with either an external or internal chain link. Either alignment is acceptable as long as there are twelve chain pins between the markings.
- There should be twelve chain pins (2) BETWEEN
the exhaust cam phaser triangle marking (1) and the intake cam phaser circle marking (3) as viewed from either the front or rear of the cam phasers.CAUTION:
Always reinstall timing chains so that they maintain the same direction of rotation. Inverting a previously run chain on a previously run sprocket will result in excessive wear to both the chain and sprocket.
- Both left and right side camshafts should be at top-dead-center, with the alignment holes (1) positioned vertically.NOTE:
It may be necessary to rock the camshaft slightly (a few degrees) with a wrench (2) when installing the camshaft holder.
- Install the (special tool #2025200090, Holder, Camshaft) (1) on both left and right side camshafts.
- Mark the direction of rotation on the following timing chains using a paint pen or equivalent to aid in reassembly:
- Left side cam chain
- Right side cam chain
- Oil pump chain
- Primary chain
- Reset the right side cam chain tensioner by pushing back the tensioner piston and installing Tensioner Pin (special tool #8514A, Pins, Tensioner) (1).
- Reset the left side cam chain tensioner by lifting the pawl (1), pushing back the piston (2) and installing Tensioner Pin (special tool #8514A, Pins, Tensioner) (3)
Refer to RESETTING LEFT CAM CHAIN TENSIONER .
- Disengage the oil pump chain tensioner spring (3) from the dowel pin (2) and remove the oil pump chain tensioner (1).
- Remove the oil pump sprocket retaining bolt (4) and remove the oil pump sprocket (5) and oil pump chain (6).
- Install the (special tool #2025102090, Holder, Camshaft Phaser - Right-Rear Cyl Head) (2) between the right side intake and exhaust phasers (1), with the tool number facing up.
- Loosen, but do not remove, the right side exhaust oil control valve (1).
- Loosen, but do not remove, the right side intake oil control valve (1).
- Remove the (special tool #2025102090, Holder, Camshaft Phaser - Right-Rear Cyl Head).
- Remove the oil control valve from the right side intake cam phaser.
- Pull the right side intake cam phaser off of the camshaft and remove the right side cam chain.
- If required, remove the oil control valve and pull the right side exhaust cam phaser off of the camshaft.
- Install the (special tool #2025101090, Holder, Camshaft Phaser - Left-Front Cyl Head) (2) between the intake and exhaust phasers (1), with the tool number facing up.
- Loosen, but do not remove, the left side exhaust oil control valve (1).
- Loosen, but do not remove, the left side intake oil control valve (1).
- Remove the (special tool #2025101090, Holder, Camshaft Phaser - Left-Front Cyl Head), leaving the Camshaft Holder in place.
- Remove the oil control valve from the left side exhaust cam phaser.
- Pull the left side exhaust cam phaser off of the camshaft and remove the left side cam chain.
- If required, remove the oil control valve and pull the left side intake cam phaser off of the camshaft.
- Reset the primary chain tensioner (2) by pushing back the tensioner piston and installing Tensioner Pin (special tool #8514A, Pins, Tensioner) (3). Remove the two bolts (1) and remove the primary chain tensioner.
- Remove the idler sprocket retaining bolt (2) and washer (3).
- Remove the primary chain, idler sprocket and crankshaft sprocket as an assembly.
- If required, remove the two bolts (6) and the left side cam chain tensioner (5).
- If required, remove the two bolts (4) and the left side cam chain guide (2) and tensioner arm (1).
- If required, remove the two bolts (4) and the right side cam chain tensioner (3).
- If required, remove the three bolts (2) and the right side cam chain guide (1) and tensioner arm (6).
- Inspect all sprockets and chain guides. Replace if damaged.