Aurora V8-4.0L VIN C (1996)
Timing Chain: Service and Repair
Revised Camshaft Timing Procedure
This article has been updated with bulletin No. 83-61-29.
REVISED SETTING CAMSHAFT TIMING PROCEDURE FOR ON VEHICLE SERVICE
Setting the camshaft timing is necessary whenever the camshaft drive system has been disturbed, such that the relationship between any chain and
sprocket has been lost. Even when only one sprocket is involved, the following procedure should be observed since one crankshaft rotation will not
provide conditions where correct timing can be confirmed.
The camshafts and crankshaft events are correctly timed when the relationships shown exist. The following procedure explains how to establish this
condition. Correct timing exists when the crank sprocket and the intermediate shaft sprocket have their timing marks aligned and all four camshaft
drive pins are perpendicular (90 degrees) to the cylinder head surface.
TOOLS REQUIRED:
J 39946 Crankshaft Rotation Socket
J 39411 Flywheel Holder
1. Remove the following components for access:
a. The left camshaft cover. Refer to Valve Rocker Arm Cover Replacement (left).
b. The right camshaft cover. Refer to Valve Rocker Arm Cover Replacement (right).
c. The front cover. Refer to Engine Front Cover Replacement.
d. The three chain tensioners (the tensioners may be in their installed positions, but must be fully retracted).
e. The oil pump. Refer to Oil Pump Cover and Gear Set Removal.
2. The primary and secondary chain guides should be reinstalled if previously removed.
3. Rotate the crankshaft until the sprocket drive key is at approximately the 1 o'clock position. Use J 39946 to rotate the crankshaft.
4. Install the crankshaft and the intermediate shaft sprockets to the primary drive chain with their timing marks adjacent to each other.
5. Install the crank and intermediate sprockets over their respective shafts.
6. Rotate the crankshaft as necessary to engage the crankshaft key in sprocket without changing the relationship of the timing marks to each other.
Use J 39946 to rotate the crankshaft.
7. Install the intermediate sprocket retainer bolt.
TIGHTEN
Intermediate sprocket retainer bolt to 60 Nm (44 lb ft.).
8. Install the primary chain tensioner or release the tensioner shoe.
TIGHTEN
Tensioner mounting bolts to 25 Nm (18 lb ft.).
9. Install flywheel holder J 39411 to lock crankshaft in this position. If the engine is on a stand, an alternate method should be devised.
10. Route the secondary drive chain for the LH cylinder head over the inner row of intermediate shaft teeth.
IMPORTANT: The RE camshaft sprocket must contain the camshaft position sensor pick-up.
11. Route the secondary drive chain over the chain guide and install the exhaust camshaft sprocket to the chain, such that the camshaft drive pin
engages the sprocket notch marked LE (left head exhaust). There should be no slack in the lower section of the chain and the camshaft drive pin
must be perpendicular to the cylinder head face.
12. Install the intake camshaft sprocket into the chain so that the sprocket notch marked LI (left head intake) engages the camshaft drive pin while the
pin remains perpendicular to the cylinder head face. A hex is cast into the camshafts behind the lobes for cylinder 1 (or 2, LH) so that an open end
wrench may be used to provide minor repositioning of the camshafts.
13. Loosely install the exhaust camshaft sprocket retainer bolt.
14. Loosely install the intake camshaft sprocket retainer bolt.
15. Install the chain tensioner or release the tension on the shoe.
TIGHTEN
Tensioner mounting bolts to 25 Nm (18 lb ft.).
Camshaft sprocket bolts to 120 Nm (90 lb ft.).
IMPORTANT: The RE camshaft sprocket must contain the camshaft position sensor pick-up.
16. Route the secondary drive chain for right side cylinder head over outer row of intermediate shaft teeth and repeat steps 11 through 15 for right side
camshafts. Right side camshaft sprockets are identified as RI (right intake) and RE (right exhaust). In addition, the RE sprocket must contain the
