Chevrolet 12604896 Camshaft Assembly, Exhaust

The removal of it turns out to be complicated and special tools are needed, new camshaft sprocket bolts, which you should probably buy every time. There are three special implements required to hold the timing chain relative to the cylinder head on the intake and the exhaust side. Then the pressure of the fuel system must be released and the negative terminal of the battery must be disconnected whereas the air filter housing, the ignition coils, the spark plugs, and the valve cover should be unbolted. The timing chain tensioner is then removed, the crankshaft is turned in order to place the special tool that will loosen the camshaft actuator bolts in place. All actuators are tagged for the re assembly and the upper chain guide is also taken off. Other tools are used to secure the timing chain before the removal of camshaft actuators and camshaft solenoids. Camshaft cap is identified by its location and orientation; the camshafts are lifted off the cylinder head but all the related accessories have to remain neat. The hydraulic lash adjusters are located on the heads or issuces of their respective rockers and properly storrage with the rockers. Lash adjusters, for example, are checked for wear or damage, and the measurements of the rocker arms as well as camshaft lobes are gone through to meet a specified gauge. Any elements, which are recognized as worn beyond their acceptable limit, have to be replaced. There is also the lubrication of the rocker arms and the lash adjusters, correct setting of the camshafts and the final tightening of the bearing caps as per a set sequence. Camshaft sprocket actuators and timing chain are put in position and screwed then timing chain tensioner is reprogrammed. Last of all, the upper timing chain guide is bolted and tightened and the battery connection is restored and the process is then done.

Before undertaking the tedious process of removing and inspecting camshafts, you should gather your special tools and get some new bolts for camshaft sprockets. On a 2.0L supercharged model, start by releasing the fuel system pressure; then disconnect the negative battery terminal. Remove the valve cover and set the engine to TDC for cylinder number one, then rotate the crankshaft anti-clockwise until the engine is at 60 degrees before TDC with a diamond-shaped hole on an intake camshaft at 12 o'clock. One thing to remember is never remove camshafts with the engine at TDC number 1 or else valves will collide with pistons and cause damage to both parts. For these engines (2.0L Supercharged & 2.2L), remove upper timing chain guide & secure camshaft sprockets by special tool. To facilitate this process, buy a camshaft locking tool.Remove and put wingnuts on side holding forwardly moved tape-worm wheels.Possibly remove the Camshaft Position Actuators if working on vehicles built during or after 2009; otherwise remove Timing Chain Tensioner if working on vehicles built before 2008.Then disassemble cams while keeping caps marked as to location and direction in which they were removed.All rocker arms must be returned to their original position while all hydraulic lash adjusters should be placed along with corresponding rocker arms.The same procedure should also be used to lift up hydraulic lash adjusters after removing rocker arms from exhaust camshafts in order.Specially made tools hold chain tight & release actuator after loosening actuator bolts while holding wrench onto hexagon of camshaft.Ensure that timing chain remains propped up by locking devices.If removing cams check all engines for proper lubrication between hydraulic lash adjusters, rocker bearings lobes of cams, bearing journals and bearing journal oil clearance.Correct any deficiencies encountered by replacing the parts which are faulty.Prior to reinstallation of rocker arms, ensure they are well oiled together with hydraulic lash adjusters, camshaft must be lubricated and installed correctly.Slide the camshaft sprockets down, tighten new bolts to the required torque and align the slots with sprocket projections before securing the camshaft bearing caps.Adjust the bolts on parts that have been mispositioned during installation.Make sure that you remove Camshaft Locking Tool then install front and rear Camshaft Caps as guided by manufacturers' specifications.Replace upper timing chain guide and also install timing chain tensioner back.Reset&install tensioner & fit upper timing chain guide for it.Once it has gone through at least two complete revolutions check for any kind of resistance involved in making those revolutions.Go ahead to reconnect your battery in order to proceed with engine operation.

This is a difficult procedure, involving special tools. Read through the entire material and obtain the necessary tools before beginning. New camshaft sprocket bolts must be purchased for installation. Relieve the fuel system pressure. Disconnect the cable from the negative battery terminal. Remove the valve cover and high-pressure fuel pump. Remove the drive belt and drive belt tensioner. Set the engine to TDC. Remove the timing chain cover, the timing chain, and camshaft sprockets. Each camshaft cap should be marked for location and direction prior to disassembly. Loosen each bearing cap bolt slowly and evenly in reverse order of the tightening sequence. Lift the camshaft(s) from the cylinder head, parallel to the head surface. The caps must be installed in their original locations. Keep all parts from each camshaft together. Remove the rocker arms and place them in a suitable container, in order, for reinstallation. Remove the hydraulic lash adjusters from their bores in the cylinder head and store them with their corresponding rocker arms. Check each hydraulic lash adjuster for excessive wear, scoring, pitting, or an out-of-round condition. If the adjusters or the cylinder head bores are excessively worn, new adjusters or a new cylinder head, or both, may be required. Inspect the rocker arms for signs of wear or damage, particularly at the tip that contacts the valve stem, the socket that contacts the lash adjuster, and the roller that contacts the camshaft. Examine the camshaft lobes for scoring, pitting, galling, and evidence of overheating. Look for flaking of the hardened surface layer of each lobe. Measure the lobe height of each cam lobe on the intake camshaft and record your measurements. Compare the measurements for excessive variation; if the lobe heights vary more than 0.00 inch (0.125 mm), replace the camshaft. Inspect the camshaft bearing journals and the cylinder head bearing surfaces for pitting or excessive wear. Measure the diameter of each camshaft bearing journal at several points. If any journal is less than the specified minimum, replace the camshaft. Lubricate the rocker arms and hydraulic lash adjusters with engine assembly lubricant or fresh engine oil. Install the adjusters into their original bores, then install the rocker arms in their correct locations. Lubricate the camshaft(s) with camshaft installation lubricant or clean engine oil. With the camshaft notch at the front of the camshaft in the 12 o'clock position, install the camshaft into the cylinder head. Rotate the oil seal in the groove of the number one camshaft journal so the split line is at approximately the 12 o'clock position before installing the camshaft caps. Lubricate the camshaft bearing caps, then install the bearing caps into their original locations. Install the camshaft bearing cap bolts and hand-start the bolts. Tighten the bolts in sequence, a little at a time, to the torque. Install the camshaft actuator sprockets and timing chain, and the timing chain cover. The remainder of installation is the reverse of removal.

This is rather delicate work that must be done with special equipment and, hence, it is advisable to wade through the entire process and gather all the tools that are going to be used in the process. Start by loosening the cable connection to the negative terminal of the battery then follow by the removal of the valve cover. Rotate the engine to TDC for cylinder number one, anti-clockwise until the crankshaft reaches sixty degrees before TDC, do not remove the camshafts at TDC number one because this will damage the valves and pistons. Subsequently, take off the upper timing chain guide and in its place, fix a locking tool for the camshaft sprockets to stay locked. When c.f. loose the camshaft sprocket bolts then you can slide the camshaft sprockets forward but before that make sure that you tighten the wingnuts. Numbers are inscribed on the main part of the camshaft cap with the numeration which will show the position; each bearing cap bolt should be diluted gradually and equally so as to let the camshaft float up from the cylinder head. Group all component of each camshaft respectively to ensure that they are not misplaced. The next step is to take out the rocker arms and set aside in order that they may be refitted, together with the hydraulic lash adjusters, which must be withdrawn from the holes in the cylinder head in which they are carried. Remove and mark the position of the exhaust bearing caps then do the same thing to the rocker arms and hydraulic lash adjuster. See also that each of the hydraulic lash adjusters is worn out or not and then check their diameters to find out if they have undergone excessive wearing. Check the conditions of the rocker arms and camshaft lobes; measure height of the lobe and compare it for high inconsistency. Examine under the bearings and valley deck for wear and measure the diameter of camshaft bearing journals, and cylinder head bearing surfaces. To ensure that the bearing journals' oil clearance is accurate, clean all the bearing surfaces followed by the installation of the camshafts and the bearing journals with Plastigage across each journal, to find the width of the flattened Plastigage. If any bearing is worn out to the extent of the service limit, then it is advisable to replace the camshaft and or cylinder head. To check camshaft endplay clean the bearing surfaces fit the camshafts and bearing caps in position and use dial indicator to measure the end play of the cam shaft. In the event that the endplay is beyond the service limit, a new camshaft thrust cap should be fitted. For the installation, it is required to lubricate the rocker arms and hydraulic lash adjusters and place them in their appropriate positions and lubricate camshafts before the establishment of the same. Place the camshaft bearing caps in place, use a step like sequence to tighten the bolts, slide the camshaft sprockets and timing chain forward towards the camshafts so that the slots in the timing chain fit into the projections on the sprockets. New bolts are required to be put on and the camshaft sprockets tightened, after which the camshaft locking tool has to be withdrawn and the front and rear caps of the camshaft are to be installed. Bolt on the upper timing chain guide and turn the engine with your hands to feel some level of resistance. Finally, reconnect the battery.

For these engines, remove the upper timing chain guide and use a special tool to secure the camshaft sprockets in place. Remove the camshaft sprocket bolts and slide the camshaft sprockets forward, securing them with wingnuts. If working on 2009 and later models, remove the camshaft position actuators; for 2008 and earlier models, remove the timing chain tensioner.

The camshaft bearing caps are marked with a number, letter, and a raised arrow. The number indicates the bearing journal position from the front of the engine, the letter denotes whether it is from the intake or exhaust camshaft, and the arrow points toward the front.

Check the camshaft bearings in the block for wear and damage, looking for galling or pitting, and inspect the housing journals for any necessary replacements.

The hydraulic lash adjusters are removed and stored with their corresponding rocker arms.

Verify the timing chain holding tool's effectiveness before starting the engine, and complete the installation by reversing the removal steps.

Slide the camshaft straight out of the engine using a long bolt as a handle, supporting the shaft near the block while being careful not to damage the bearings.

If there are any concerns about the timing chain holding tool, verify the positioning of all chains and sprockets before starting the engine.

Measure the bearing journals and camshaft lobes with a micrometer to check for excessive wear or out-of-round conditions, and inspect the lobes for discoloration or damage.