GM 12686787 ADJUSTER ASM-HYD VLV LASH

A noisy lash adjuster can be isolated while the engine is idling by using a mechanic's stethoscope or a length of hose near each valve, listening at the other end, or by removing the valve cover and touching each valve spring retainer one at a time to feel for shock if a adjuster is defective. Common causes of noisy adjusters include dirt trapped inside and insufficient oil, so it's important to check the oil for fuel contamination, level, cleanliness, and viscosity before making any judgments. To remove the adjusters, first take off the valve cover and lower intake manifold, then remove the rocker arms and pushrods. Next, take out the bolts holding the roller adjuster guides to the block and remove the guides, marking them for reinstallation. Adjusters can be extracted using a special tool, a small magnet, or a machinist's scribe, but caution is advised against using pliers unless replacing the adjusters, as they may cause damage. Store the adjusters in a labeled box to ensure they are reinstalled in their original locations. Since parts for lash adjusters are not sold separately, cleaning them is often more practical than replacement. Thoroughly clean and dry the adjusters, checking for scuffing, score marks, or uneven wear, and inspect the rollers for wear or damage. When reinstalling used adjusters, ensure they go back into their original bores, soak new adjusters in oil, and coat all adjusters with moly-base grease or engine assembly lube before installation. Finally, install the adjusters and guides, tighten the bolts to the specified torque, and run the engine to check for oil leaks.

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.

In order to remove the valve covers, one has to take off camshafts and tightened paying attention to the wear points of the rocker arm and lash adjusters. We need to mark the rocker arms so that they will be reinstalled in the correct location, then pull them from the engine. The hydraulic lash adjusters become physically detached with the rocker arms being removed and can be withdrawn from the cylinder head. Rocker arms or lash adjusters that were remove should be reinstall to their original position if desire. Feel the rollers to identify cases where they are rigid; if bearings of the part are worn or damaged, the whole rocker arm will have to be replaced. Just as worth remembering, these engines do not need any valve adjustments, so the excessive wear or damage in the valve train will deepen the increased valve clearance and noise during the work of the engine. Check that the oil passage hole of each hydraulic lash adjuster is clear. Camshaft/lifter prelube should be applied at the pivot pockets, roller, and the slot that contacts the valve on each rocker arm also engine oil should must be used on the bores of hydraulic lash adjusters before putting them on the cylinder head. Place the rocker arms onto the lash adjusters after that, flip over the process of uninstallation to reinstall the rocker arms. Always ensure that you change the oil of your car and also fit in a new oil filter before you start the engine.

This operation is a somewhat complicated one, and it employs instruments that are specific to it, so make sure you read through all the directions and make sure you have all the tools you will need ready before beginning the operation. On the first step, you must unplug the cable from the negative terminal on the battery, and on the second step, take off the valve cover. Place the engine at TDC of cylinder number one and rotate the crankshaft in anti-clockwise direction to position the crankshaft at 60 degrees before TDC, while positioning the diameter shaped hole at twelve o clock position on intake camshaft. Secondly, take off the upper timing chain guide and place a particular tool that will immobilise the camshaft sprockets. Remove the bolts on the camshaft sprocket and put the sprockets aside, in addition, loosen the wing nuts that lock the sprockets in place. Another feature is that each camshaft cap features a number, which shows the position of the camshaft; each bearing cap bolt should be loosened gradually but firmly enough to lift the camshaft from the cylinder head. Take out the rocker arms while in so doing retain them and the hydraulic lash adjusters so that they can be refitted. Remove the exhaust bearing caps followed by the rocker arms and the lash adjusters in like manner. Each hydraulic lash adjuster needs to be checked for wear and each of them needs to have its diameters measured; if the lash adjusters are out of round, they will have to be exchanged. Inspect the rocker arms for any signs of wear or damage, the camshaft lobes also for wear, the thickness of the lobe and if there is a massive variation replace the camshaft. Check the camshaft bearing journals for wear and measure the diameter of each; replace any that do not conform to minimum size. To check the bearing journal oil clearance, all the bearing surfaces must be cleaned, followed by installing the camshafts together with the bearing caps with Plastigage across the journal, and as the bolts are tightened, the width of the flattened Plastigage is then to be measured. If any oil clearance is over the service limit, then the camshaft, or the cylinder head should be replaced. On camshaft end play, the bearing surfaces must be cleaned and the camshafts and bearing caps put in place before using a dial indicator to check on the end play. If the endplay is at any time beyond the service limit, it is advisable to replace either the camshaft thrust cap or the camshaft. For assembly, apply oil to the rocker arms and the lash adjusters and then position them as earlier used. Oil the camshafts and then place it properly and follow through the camshaft bearing s which have to be tighten in sequence. Move the camshaft sprockets and the timing chain right to the camshafts, so that the slots get into the corresponding projections on the sprockets and screw new bolts. Take out the camshaft locking tool, screw and tighten the front and rear camshaft cap to the recommended torque. The upper timing chain guide must be fitted, and the engine has to be rotated by hand in order to feel the level of the resistance. Finally, reconnect the battery.

To gain access to the camshafts the battery cable needs to be disconnected and the engine set to 60 degree BTDC of cylinder no. 1. First take off valve cover(s) and timing belt, next undo the camshaft sprockets noting which one is which and disposing of the bolts appropriately. This is to mark the position of the camshaft dowels so that it becomes easier to align it correctly when reassembling it. Leverage each of the camshaft cap bolt in a gradual manner beginning with the centre bearing caps, the intent being to lift the camshaft in a direction perpendicular to the cylinder head surface. Again, observe the labeling of the camshaft bearing caps on both the front and rear cylinder heads and ensure you take its picture to help you when reinstalling them. The camshaft and its seal should be unbolted, the Lash Adjusters should be serviced separately by placing each of them in twelve separate small containers to avoid confusion. Check the camshafts and Lash Adjusters for wear; mic each Lash Adjuster OD and look for signs of excessive wear or taper. Check the look of the camshaft lobes and then take measurements of the lobe heights in an effort to find out whether they have differences that are exceptionally high. Inspect bearing journals and cylinder head surfaces for wear; measure the diameter of each journal; check running clearance with Plastigage. Any bearing that has exceeded service limit must be replaced along with the camshaft or the cylinder head as the case may be. For engine installation, the engine is set at 60 degrees before the TDC, the Lash Adjuster bores and the Lash Adjusters being oiled before being repositioned in their correct positions. As a change, new camshaft oil seals must be fitted and the camshaft journals and lobes must be oiled. Place the camshafts back in the originally intended positions so that the pins will be in the least tension as you apply the spring. Apply some anaerobic sealant between the camshaft caps and the cylinder head with an aim of sealing oil leakage later on, then fit the bearing caps, bolts, spacers etc as per the referred positions in the procedure. Tightening of these bearing cap bolts is to be done progressively in quizzed sequence. Remove any excess sealant and go on to fit the sprockets and this timing belt.

Always install new lifters as well, as old lifters should not be used with a new camshaft.

They must be returned to their original position on the engine.

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.

If the lifters are stuck due to gum and varnish buildup, they can be extracted using a special tool or, in some cases, a small magnet or fingers.

Lubricate the camshaft bearing journals and lobes, then slide the camshaft into the engine, supporting it near the block. Turn the camshaft until the dowel pin is in the 3 o'clock position, install the camshaft thrust plate, and tighten the bolts to the specified torque.

For installation, lubricate the rocker arms and lash adjusters before placing them back in their original positions. Then, lubricate and install the camshafts, install the camshaft bearing caps, tightening them in sequence, and reinstall the camshaft actuators and timing chain. Rotate the engine by hand to check for resistance.

Perform two manual engine revolutions, checking for resistance. Complete the remaining installation steps, reconnect the battery, and proceed with engine operation.

If the adjusters or the cylinder head bores are excessively worn, new adjusters or a new cylinder head, or both, may be required.

The entire rocker arm will need to be replaced.

The removal process involves removing the valve covers and camshafts, then removing the rockers and lash adjuster socket on the rocker.

After removing the cam sprocket, do not rotate the crankshaft to avoid incorrect timing and potential engine damage.

Remove the lifter retainers and lifters, taking care to keep them clean. Each retainer houses four individual lifters that must be returned to their original locations if reused.

Start by disconnecting the cable from the negative battery terminal and setting the engine to 60-degrees before TDC.

Lifters can be extracted using a special tool, a small magnet, or fingers. A machinist's scribe can help pull them out by positioning the point under the retainer ring.

For 2.0L, 2.4L, and 2009 and later 2.2L engines, reinstall the camshaft actuators aligned with the marked positions and secure them with new bolts, tightening while holding each camshaft. Remove the camshaft locking tool and install the front and rear camshaft caps, torquing them to specifications. Install the upper timing chain guide and reset and install the timing chain tensioner.

Apply anaerobic sealant between the camshaft cap and cylinder head on the front caps.