GM 12648846 Lifter Assembly, Valve

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After installing the camshaft, you should: 1. Refill the cooling system. 2. Change the engine oil and filter. 3. Start the engine and check for leaks.

The lifters should be stored in a clearly labeled box before removing them.

To determine the extent of cam lobe wear, check the lobe lift before removing the camshaft. Position the number one piston at TDC on the compression stroke. Remove the valve cover and loosen the rocker arm nuts to access the pushrods. Mount a dial indicator on the engine and position the plunger against the top of the first pushrod. Zero the dial indicator and slowly turn the crankshaft in the normal direction of rotation until the indicator needle stops and moves in the opposite direction, indicating maximum cam lobe lift. Record this figure and repeat the check for each valve. If the cam lobe lift is less than specified, install a new camshaft. To check for a noisy valve lash adjuster, use a mechanics stethoscope or a length of hose near each valve while listening for excessive clearance in the valvetrain. If a lash adjuster is defective, it will be evident from the noise. Removing the lash adjusters requires removing the cylinder head. Remove the lash adjuster guides and extract the lash adjusters using a special removal tool, magnet, or scribe. Clean the lash adjusters and inspect them for scuffing, score marks, and uneven wear. Check the rollers for wear and damage. Replace the lash adjusters if necessary. To remove the camshaft, remove the front cover, timing chain, and sprockets. Unbolt and remove the oil pump drive and the camshaft thrust plate. Carefully pull the camshaft out of the block. Clean and inspect the bearing journals for damage. Measure the bearing journals and camshaft lobes. Check the lobes for discoloration, score marks, chipped areas, pitting, and uneven wear. If the lobes are in good condition and the measurements are as specified, the camshaft can be reused. Lubricate the camshaft bearing journals and lobes with assembly lube and slide the camshaft into the engine. Install the thrust plate and tighten the bolts. Reinstall the oil pump drive. If reusing the lash adjusters, install them in their original bores and coat them with assembly lube. Lubricate the lash adjuster bores with engine oil and install the lash adjusters. Install the lash adjuster guides and reinstalling the cylinder head. Install the pushrods, pushrod guides, rocker arms, and rocker arm retaining nuts. Tighten the rocker arm nuts.

If the cam lobe lift is 0.003 inches less than specified during the measurement, it indicates cam lobe wear, necessitating the installation of a new camshaft.

To remove the camshaft, start by removing the intake manifold, rocker arms, pushrods, timing chain, camshaft sprocket, and balance shaft drive gear. Also remove the fan, radiator, and condenser. Store the lash adjusters in a labeled box and remove the lifter retainer. Use a special tool, magnet, or your fingers to extract the lash adjusters from the bores. Remove the camshaft retainer plate and use three 6-inch long, 5/16-18 bolts as a handle to remove the camshaft from the block. During inspection, clean the lash adjuster and camshaft with solvent and check for wear and damage. Measure the journals and cam lobes for wear. If the camshaft and bearings are damaged, they will need to be replaced. For installation, lubricate the camshaft bearing journals and cam lobes with assembly lube and slide the camshaft into the engine. Install the camshaft thrust plate, balance shaft drive gear, timing chain, and sprockets. Lubricate the lash adjusters with clean engine oil and install them in the block. The remainder of installation is the reverse of removal. Finally, refill the cooling system, change the engine oil and filter, start the engine and check for leaks.

After removing the lifters, you should clean them and inspect them for scuffing, score marks, and uneven wear. Additionally, check the rollers for wear and damage. Replace the lifters if necessary.

To check Lash Adjuster before removal, start by removing the valve covers and loosening the rocker arm nuts to pivot the rocker arms for access to the pushrods. Mount a dial indicator on the engine, positioning the plunger directly above the first pushrod. Ensure the engine's electrical connectors from the distributor are disconnected. Slowly turn the engine until the pushrod is at its lowest point (base circle of the camshaft lobe), then zero the dial indicator. Rotate the crankshaft in the normal direction until the indicator needle reaches its peak and begins moving in the opposite direction, marking maximum cam lobe lift. Record this measurement and repeat the check for all lobes, comparing the results. If cam lobe lift is 0.003 inches less than specified, cam lobe wear has occurred, necessitating a new camshaft installation. Also, remove the fan shrouds, fan, radiator, and condenser if applicable. Ensure proper labeling and storage of the lifters before removing them, and remove the lifter retainer. Take care not to attempt camshaft withdrawal with the lifters in place. Various methods can be used to extract the lifters from the bores. Afterward, remove the camshaft retainer plate by removing the two Torx bolts, taking note of the correct orientation. Thread three 6-inch long, 5/16-18 bolts into the camshaft sprocket bolt holes for handling when pulling the camshaft straight out, avoiding damage to the bearings. During inspection, visually examine the cam lobes and bearing journals for wear, scoring, pitting, galling, overheating evidence (discoloration), and flaking of the hardened surface. Measure the diameter of each camshaft journal and the lift of each camshaft lobe using a micrometer and compare the measurements with the specifications. If any journal diameter falls below the specified value, replace the camshaft. For camshaft bearing replacement, it's advisable to seek assistance from an automotive machine shop, as it involves specialized tools and expertise. For installation, lubricate the camshaft bearing journals and cam lobes with Lash Adjuster assembly lube, then carefully slide the camshaft into the engine while supporting it near the block to prevent damage to the bearings. Turn the camshaft until the dowel pin is at 3 o'clock and install the camshaft thrust plate, tightening the bolts. Install the balance shaft drive gear, aligning the dowel pin and ensuring proper alignment of the balance shaft timing marks. Proceed to install the timing chain and sprockets. Lubricate the lifters with clean engine oil and install them in the block, making sure to return them to their original locations if reusing the original lifters. If a new camshaft is installed, use new lifters as well. Finally, complete the remaining installation steps in reverse order, and before starting the engine, change the oil and install a new oil filter.

The steps for installing the camshaft are as follows:1. Lubricate the camshaft bearing journals and cam lobes with assembly lube.2. Slide the camshaft into the engine.3. Install the camshaft thrust plate.4. Install the balance shaft drive gear.5. Install the timing chain and sprockets.6. Lubricate the lifters with clean engine oil.7. Install the lifters in the block.8. Complete the installation in reverse order of removal.

To remove the camshaft, start by disconnecting the cable from the negative battery terminal and relieving the fuel system pressure. Then, remove the radiator, auxiliary automatic transmission fluid cooler (if equipped), power steering cooler, air conditioning condenser, valve covers, intake manifold, rocker arms, pushrods, timing chain and sprockets, and cylinder heads. Before removing the lash adjusters, arrange to store them in a clearly labeled box. Remove the lash adjusters and camshaft retainer plate, and use a bolt as a handle to carefully pull out the camshaft. To inspect the camshaft, measure the lobe height and base circle to determine the lobe lift. Compare the results to the specifications and replace the camshaft if necessary. Inspect the camshaft bearing journals for wear and damage, and measure them with a micrometer. Check the camshaft lobes for discoloration, score marks, chipped areas, and uneven wear. Clean and inspect the lash adjusters for damage, wear, and proper function. Install the camshaft by lubricating the bearing journals and lobes with assembly lube, sliding it into the engine, and securing it with the camshaft thrust plate. Install the timing chain and sprockets, camshaft position sensor, and lash adjusters. Finally, refill the cooling system, change the oil, and install a new oil filter before starting and running the engine.

After installing the camshaft, proceed to install the balance shaft drive gear, aligning the dowel pin and ensuring proper alignment of the balance shaft timing marks. Then, install the timing chain and sprockets.

The lifters should be stored in a clearly labeled box before removing them.

During inspection of the camshaft, you should:1. Clean the lifter and camshaft with solvent.2. Check for wear and damage on the lifter and camshaft.3. Measure the journals and cam lobes for wear.4. Replace the camshaft and bearings if they are damaged.

There is 1 lifter per order