GM 12589011
Timing Chain

It is important to remove the engine front cover when you want to replace the timing chain and sprockets. Next, pull out the right bank secondary camshaft drive chain tensioner, then the right bank secondary camshaft drive chain shoe, and finally, right bank secondary camshaft drive chain guide. And then, take the chains off from the right bank secondary camshaft drive and the Timing Chain Tensioner. Next, remove the timing chain upper guide and the timing chain. For installation, install the timing chain (120), primary upper camshaft drive chain guide (122) and Timing Chain Tensioner (123) respectively. Then install the right bank secondary camshaft drive chain (124), the right bank secondary camshaft drive chain guide (125), the right bank secondary camshaft drive chain shoe (126) and eventually the right bank secondary camshaft drive chain tensioner (127). Finish the process by replacing the engine front cover.

Start by removing the engine front cover to replace the Timing Chain along with sprockets. Guide the Crankshaft to its proper position where timing marks match up. Both the camshaft sprocket and the Timing Chain dampener must be aligned before removal while the Timing Chain dampener needs to line up with the Crankshaft sprocket. To access the camshaft sprocket and Timing Chain, first remove the camshaft sprocket bolt, then uninstall the camshaft sprocket with the Timing Chain, followed by removing the Crankshaft sprocket and Timing Chain dampener bolts to extract the dampener. Begin installation by putting on the Crankshaft sprocket before applying prelube gm p/n 12345501 (Canadian P/N 992704) or equivalent to the sprocket thrust surface. After installing the Timing Chain dampener bolt to a torque of 21 nm (15 ft. Lbs.), final installation can proceed. Beginning with the camshaft gear, carefully place the Timing Chain through the Crankshaft gear while keeping the camshaft sprocket supported by the chain. Position the Crankshaft timing mark directly under the timing mark on the bottom of the Timing Chain dampener and the timing mark on the camshaft gear through its center line of the locator hole so it aligns with the timing mark on the top of the chain dampener. Correctly position the dowel in the camshaft so it enters the camshaft sprocket's dowel hole before using the mounting bolt to draw the sprocket onto the camshaft. Fasten and torque the camshaft sprocket bolt up to 140 nm (103 ft. Lbs.). Release alignment of the Crankshaft and camshaft sprocket by applying engine oil and reinstall the engine front cover.

The replacement process for timing chains and sprockets starts by removing the Oil Pump while using crankshaft socket (J39946) to set primary timing marks. Removing secondary timing chains requires initial separation from the primary drive chain tensioner along with the oil outlet tube extraction. Begin by removing the guide bolts from the timing chain system together with its guide component while also removing the camshaft intermediate sprocket retaining bolt. An assembly consisting of the timing chain together with the crankshaft sprocket and camshaft intermediate sprocket must be taken out. All camshaft timing drive components need cleaning followed by inspection before they become part of the installation. The timing marks of the camshaft intermediate and crankshaft sprockets must align vertically before installing the timing chain on the drive sprockets. Install the timing chain, crankshaft sprocket and camshaft intermediate sprocket together through using the crankshaft socket (J39946) while keeping the keyway at a 1 o'clock position. The installation of camshaft intermediate sprocket requires a nut torque of 60 nm (44 ft. Lbs.). Afterward install the primary drive chain guide together with its bolts at 25 nm (18 ft. Lbs.) torque specification before installing the primary drive chain tensioner. You should install the oil outlet tube, followed by its bolts while tightening them to 10 nm (89 inch lbs.). Install the secondary timing chains afterward. Proceed by removing the pin from the primary timing chain tensioner release lever then checking the primary timing marks stand vertically before installing the Oil Pump.

Remove the right bank camshaft intermediate drive chain idler.

Start with the left bank secondary camshaft drive chain, followed by the left bank camshaft intermediate drive chain idler, left bank secondary camshaft drive chain guide, left bank secondary camshaft drive chain shoe, and left bank secondary camshaft drive chain tensioner.

Remove the camshaft sprocket bolt, followed by the camshaft sprocket and timing chain, then the crankshaft sprocket, and the timing chain dampener bolts to take out the timing chain dampener.

Install the primary camshaft drive chain.

Remove the right bank secondary camshaft drive chain guide (Guide).

The chain guide.

Align the three black links on the secondary timing chain with the corresponding timing marks on the bank 2 exhaust actuator, bank 2 intake actuator, and intermediate sprocket.