GM 12637743
Timing Chain

In order to change the left Timing Chain, pull out the spark plugs so that they ease the rotation of the Crankshaft. Then, remove the engine front cover, the right bank Timing Chain, and the primary camshaft drive chain. Subsequently, replace the left bank Timing Chain Tensioner, the left bank Timing Chain shoe and the left bank Timing Chain guide. Then take out the left bank camshaft intermediate drive chain idler and left bank Timing Chain. Clean, inspect all camshaft timing drive components and replace those that are needed. Installation starts with the installation of left bank Timing Chain, followed by the installation of the left bank camshaft intermediate drive chain idler, left bank Timing Chain guide, left bank Timing Chain shoe, and the left bank Timing Chain Tensioner. Then install the primary camshaft drive(Output), and the right bank Timing Chain. Lastly, reinstall the front cover of the engine and the plugs.

Start by removing the engine front cover before commencing left side Timing Chain replacement. Starting with the right bank Timing Chain Tensioner you must also remove right bank Timing Chain shoe and guide before proceeding. Start by taking out the right bank Timing Chain followed by removing the primary camshaft drive chain tensioner and then both the primary upper camshaft drive chain guide and primary camshaft drive chain. The following sequence requires removal of the right bank camshaft intermediate drive chain idler then the left bank Timing Chain Tensioner followed by the left bank Timing Chain shoe and guide. To perform the next step remove the left bank camshaft intermediate drive chain idler followed by the left bank Timing Chain. All timing drive components should receive cleaning and inspection before installation of required replacement parts. Begin installation by placing the left bank Timing Chain first then proceed with the left bank camshaft intermediate drive chain idler followed by the left bank Timing Chain Guide and left bank Timing Chain shoe and left bank Timing Chain Tensioner. You should begin by setting the right bank camshaft intermediate drive chain idler followed by installing the primary camshaft drive chain and primary upper camshaft drive chain guide and primary camshaft drive chain tensioner. Finish the installation by adding the right bank Timing Chain and its corresponding guides, shoes and tensioner which precedes the engine front cover replacement.

Replacement of the right-side Timing Chain begins with removing the Oil Pump. With tool j 39946 (J 39946) rotate the Crankshaft until the primary timing gear marks meet up. Keep the actuator solenoids attached when you remove the right Camshaft position actuator housing. Special caution is essential when working with the en 46328 (EN 46328) installed on bank 1 (right) camshafts. Use j 39946 or en 46328 to loosen then remove right Timing Chain Tensioner bolts together with the tensioner. Reverse the Camshaft movement using an open-end wrench during removal of bank 1 (right) exhaust and intake Camshaft position oil control valves. The technicians should first detach the Timing Chain from actuator teeth before removing right exhaust and intake Camshaft position actuators from their Camshaft position. All components of the Camshaft timing drive need clean-up and inspection. Upon installation position all three black links of the Timing Chain in precise alignment with timing marks found on bank 1 exhaust and intake actuators and the intermediate sprocket. Mount the Timing Chain to the intermediate sprocket while maintaining precise alignment. Secure the actuators on their camshafts so their timing marks face directly opposite the cylinder head deck surface. Then loosely install the oil control valves before tightening them to 120 n.m (89 lb ft) as a preventive measure against Camshaft rotation. Installation must start with the right Timing Chain Tensioner followed by en 46328 removal then right Camshaft position actuator housing replacement before finishing with the Oil Pump.

Starting the left side Timing Chain replacement operation requires removal of the engine front cover. Start by removing the right bank Timing Chain Tensioner before taking out both the right bank Timing Chain shoe and guide. First remove the right bank Timing Chain followed by the primary camshaft drive chain tensioner then the primary upper Timing Chain Guide and the primary Timing Chain. Work to remove subsequently the right bank camshaft intermediate drive chain idler then the left bank Timing Chain Tensioner followed by the left bank Timing Chain shoe and guide. Next move ahead with the removal of the left bank camshaft intermediate drive chain idler and left bank Timing Chain. Test all camshaft timing drive parts before installing fresh components as required. The left bank Timing Chain serves as the starting point before moving to the left bank camshaft intermediate drive chain idler followed by installation of the left bank Timing Chain Guide and left bank Timing Chain shoe and left bank Timing Chain Tensioner. Proceed with the right bank camshaft intermediate drive chain idler followed by the primary Timing Chain followed by the primary upper Timing Chain Guide and finally the primary Timing Chain Tensioner. Following right bank Timing Chain installation should be the right bank Timing Chain Guide and right bank Timing Chain shoe and right bank Timing Chain Tensioner. Install the engine front cover as the last step.

The repair process for changing a Camshaft Timing Chain starts with the removal of the number 1 cylinder's Spark Plug followed by turning the Crankshaft to a clockwise direction until the number 1 Piston gets to top dead center (TDC) on the exhaust stroke. Start by taking off both the Camshaft cover and the engine front cover. First detach upper Timing Chain guide bolts and guide while also extracting the tensioner unit to release tension from the chain. Use a 24 mm wrench to hold the exhaust Camshaft during the procedure after you remove the Timing Chain Tensioner. The exhaust Camshaft actuator bolt needs to be discarded before you extract the actuator from the Camshaft and Timing Chain. After you extract the Timing Chain Tensioner guide bolt with its guide remove the fixed Timing Chain guide access plug together with its guide bolts and guide. When working on the intake Camshaft actuator maintain the steps exactly like the exhaust Camshaft actuator but use the top of the cylinder head to extract the Timing Chain then remove the Timing Chain Crankshaft sprocket. For a balance shaft Timing Chain or sprocket replacement the technician must unfasten the balance shaft drive chain tensioner bolts while also removing the tensioner and the adjustable and small balance shaft drive chain guides. Proper installation of the balance shaft drive sprocket requires correct balance shaft timing to prevent engine vibration. The balance shaft drive chain undergoes installation with timed colored links facing the timing marks on both sprockets before installing the upper and smaller chain guides followed by the adjustable guide and tightening all components to torque specs. Reset the Timing Chain Tensioner through plunger compression followed by securing it with a paper clip. Mount the balance shaft drive chain tensioner correctly while double-checking that the intake and exhaust Camshaft notches maintain proper alignment. Before assembly place the Timing Chain drive sprocket so its timing mark faces the proper orientation then position the intake Camshaft actuator with its timing mark matching the colored link. Guide the Timing Chain along the Crankshaft sprocket pathway while keeping both colored links and timing marks in sequence. Fit the fixed Timing Chain guide onto the assembly while installing its bolts next add the upper Timing Chain guide and torque it to the indicated value. Before installing the Timing Chain Tensioner assembly technician needs to reset the Timing Chain Tensioner and inspect the seal for damage and ensure the threaded hole remains clean. Start by releasing the Timing Chain Tensioner then apply torque to the intake and exhaust Camshaft actuator bolts using the angle meter to reach a specified torque measure along with an additional angular measurement. Installation of the Timing Chain oiling nozzle is followed by applying sealant to the Timing Chain guide bolt access hole plug which should be installed and tightened to specification before reinstalling both engine front and Camshaft covers along with the number 1 cylinder Spark Plug.

The first step for camshaft Timing Chain and sprocket replacement includes executing engine front cover removal. Start by removing the camshaft sprocket bolts before removing both the camshaft sprocket and Timing Chain. Begin by taking out the crankshaft sprocket and the Timing Chain dampener bolts followed by removing the Timing Chain dampener. Begin your installation by placing the crankshaft sprocket in position then apply prelube gm p/n 12345501 (Canadian P/N 992704) or equivalent to the crankshaft sprocket thrust surface. Mount the Timing Chain dampener across the studs and use a torque wrench to tighten bolts to 21 nm (15 lb ft). Position the crankshaft timing mark directly alongside the timing mark which appears on the bottom side of the Timing Chain dampener . Use one hand to grip the camshaft sprocket as you let the Timing Chain drop below and carefully assemble the chain onto the crankshaft gear. Line up the cams gear's timing indicator with the timing indicator on the Timing Chain dampener' top section before confirming the small dowel on the camshaft inserts its matching hole in the camshaft sprocket. To install the camshaft sprocket draw it in position onto the camshaft while using the mounting bolts. Then lubricate crankshaft and camshaft sprocket surfaces with engine oil followed by torque bolt tightening to 16 nm (12 lb ft). Replace the engine front cover when the process is complete.

To replace the timing chain and sprockets, start by removing the cylinders' spark plugs to facilitate the Crankshaft rotation. Then, pull the engine front cover away; remove the tensioner for right bank second timing chain shoe and guide. Afterwards, remove the right bank secondary timing chain, the Timing Chain Tensioner, the timing chain upper guide and the timing chain. Lastly, extract the Crankshaft sprocket from the nose of Crankshaft. For installation, make sure it has the timing mark visible before placing it on top of the Crankshaft nose with the notch in the pin direction. Slide the sprocket up to touch the step on the Crankshaft ensuring the Crankshaft is in the stage one timing position and ensure that the timing mark is lined up with the stage one timing mark on top of the oil pump cover using the en 46111 Crankshaft rotation socket (EN 46111). Go on to install the timing chain, the upper Timing Chain Guide, the Timing Chain Tensioner, the right bank secondary timing chain, the right bank secondary Timing Chain Guide, the right bank secondary timing chain shoe and the right bank secondary Timing Chain Tensioner. Finally, replace the spark plugs and the engine front cover.

Start replacing the left Timing Chain by uninstalling spark plugs first then the engine front cover. Start by removing the right bank Timing Chain and after that remove the primary camshaft drive chain. First remove the left bank Timing Chain Tensioner, shoe, guide, and the camshaft intermediate drive chain idler before proceeding with the left bank Timing Chain itself. All components for camshaft timing drives must receive a clean-up treatment while you will need to replace any units that show signs of wear. Begin installation by placing the left bank Timing Chain first and follow the steps with the camshaft intermediate drive chain idler then Timing Chain guide and shoe then tensioner. The primary camshaft drive chain should be installed before the right bank Timing Chain after engine front cover reattachment and Spark Plug installation.

Starting the right Timing Chain replacement requires Spark Plug removal for Crankshaft rotation and engine front cover detachment. Strategically remove the right bank Timing Chain Tensioner followed by both the right bank Timing Chain shoe and guide before completing with the right bank Timing Chain itself. Start by fitting the right bank Timing Chain then install the guide before putting on the right bank Timing Chain shoe and tensioner. Return to service by replacing engine front cover and spark plugs.

You should start maintenance on the right side Timing Chain by taking off the engine front cover. The successful Crankshaft rotation depends on removing spark plugs first. While replacing the right bank Timing Chain Tensioner proceed with removing the right bank Timing Chain shoe before installing the right bank Timing Chain Guide. Proceed with taking away the right bank Timing Chain. Begin by confirming the stage 1 camshaft timing alignment. Then install the new right bank Timing Chain followed by the right bank Timing Chain Guide, right bank Timing Chain shoe, and right bank Timing Chain Tensioner. Close this procedure by installing both the spark plugs and the engine front cover.

To change the timing chain and sprockets, start by removing the engine front cover, then remove the spark plugs in order to facilitate the rotation of the Crankshaft. Then, remove the right bank secondary camshaft drive chain tensioner, secondary camshaft drive chain shoe, and secondary camshaft drive chain guide and then take out the right bank secondary camshaft drive chain. Follow to the removal of the Timing Chain Tensioner, in conjunction with the upper guide and the timing chain, the Crankshaft sprocket from the nose of the Crankshaft shall also be removed. For installation, ensure that the Crankshaft sprocket position has the timing mark visible and in line with the pin on Crankshaft, sliding it over until the sprocket contacts the step in the Crankshaft. Check the Crankshaft's position at stage one timing position with the timing mark in stage one timing mark on the oil pump cover using the en 46111. Mount the timing chain, then primary upper camshaft drive chain guide and finally installing the Timing Chain Tensioner. Next, install the right bank secondary camshaft drive chain, its guide, shoe, as well as the tensioner. Lastly, replace the spark plugs and the engine front cover.

Install the right bank camshaft intermediate drive chain idler, the primary camshaft drive chain, the primary upper camshaft drive chain guide, and the primary camshaft drive chain tensioner.

Install the left bank camshaft intermediate drive chain idler (Idler), the left bank secondary camshaft drive chain guide (Guide), the left bank secondary camshaft drive chain shoe (Shoe), and the left bank secondary camshaft drive chain tensioner (Tensioner).

Install the right bank secondary camshaft drive chain guide.

Install the left bank camshaft intermediate drive chain idler (12356), the left bank secondary camshaft drive chain guide (12355), the left bank secondary camshaft drive chain shoe (12354), and the left bank secondary camshaft drive chain tensioner (12353).

Remove the left bank camshaft intermediate drive chain idler (Idler) and the left bank secondary camshaft drive chain (Chain).

Begin by removing the spark plugs to facilitate crankshaft rotation.

Install the left bank camshaft intermediate drive chain idler, the left bank secondary camshaft drive chain guide, the left bank secondary camshaft drive chain shoe, and the left bank secondary camshaft drive chain tensioner.

Install the right bank secondary camshaft drive chain tensioner.

Remove the right bank secondary camshaft drive chain shoe and guide.

Remove the spark plugs to facilitate crankshaft rotation.

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

Remove the right bank secondary camshaft drive chain itself.

Reinstall the spark plugs and the engine front cover.

Install the primary camshaft drive chain tensioner.

Remove the left bank camshaft intermediate drive chain idler and the left bank secondary camshaft drive chain.

Clean and inspect all camshaft timing drive components, replacing any that are necessary.

Reinstall the engine front cover.

Reinstall the engine front cover.

Install the left bank camshaft intermediate drive chain idler, the left bank secondary camshaft drive chain guide, the left bank secondary camshaft drive chain shoe, and the left bank secondary camshaft drive chain tensioner.

Ensure proper alignment when assembling the secondary timing chain to the intermediate sprocket.

The secondary camshaft drive chain tensioner, shoe, guide, and chain.

Ensure the stage 1 camshaft timing is correct.

Clean and inspect all camshaft timing drive components and replace as necessary.

Remove the left camshaft position actuator housing without detaching the actuator solenoids.

Install the timing chain dampener and its bolts, tightening them to 21 N.m (15 lb ft).

Locate the No. 1 piston at approximately 60 degrees before top dead center, indicated by the diamond-shaped hole on the intake camshaft sprocket at the 12 o'clock position.

Reinstall the spark plugs and the engine front cover.

Tighten to 75 Nm (55 lb ft) and release the timing chain tensioner using a suitable tool.