GM 12721203 LIFTER ASM-VLV

Remove the lifter retainers and lifters, taking care to keep them clean. Note that each retainer houses four individual lifters that must be reinstalled in their original positions if reused.

The most common cause of noise is dirt trapped between the plunger and lifter body.

To determine cam lobe wear, you should first position the number one piston at TDC on the compression stroke. Then, loosen the rocker arm nuts and pivot the rocker arms sideways. Afterward, 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 begins to move in the opposite direction. Record this figure and repeat the check for each valve.

To determine the extent of cam lobe wear, 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. Then, mount a dial indicator on the engine, position the plunger against the top of the first pushrod, and zero the dial indicator. 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.

Begin by removing the intake manifold or supercharger, valve covers, rocker arms, pushrods, timing chain, timing chain tensioner, cylinder heads, oil pan, oil pump, oil deflector, radiator, air conditioning condenser, and the Camshaft Position sensors.

Before lifter removal, it is important to store them in a clearly labeled box to ensure they are reinstalled in their original locations.

Thread a bolt into the camshaft sprocket bolt hole to use as a handle when removing the camshaft. Carefully and slowly pull the camshaft out, supporting it near the block to prevent damage to the bearings.

Before removing the camshaft, check the lobe lift and ensure that if a new camshaft is being installed, new lifters must also be used.

To remove the camshaft, you should first remove the intake manifold, rocker arms, pushrods, timing chain, and camshaft sprocket. If applicable, also remove the balancer shaft drive and driven gears. Carefully pull the camshaft out, supporting it near the engine block.

Begin by removing the engine from the vehicle, followed by the valve covers and the intake manifold. Next, take out the rocker arms and pushrods, then remove the timing chain and sprockets, and subsequently the cylinder heads.

To determine the extent of cam lobe wear, 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. Then, mount a dial indicator on the engine, position the plunger against the top of the first pushrod, and zero the dial indicator. 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.

A noisy valve lifter can be isolated when the engine is idling by using a mechanic's stethoscope or a length of hose near each valve while listening at the other end. Alternatively, you can remove the valve cover and touch each valve spring retainer with the engine idling to feel for shock if a lifter is defective.

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.

If reusing lifters, install them in their original bores, coating them with moly-base grease or engine assembly lube, and lubricate the bearing surfaces of the lifter bores with engine oil.

The initial steps to remove the camshaft are disconnecting the cable from the negative battery terminal and relieving the fuel system pressure.

The steps to remove the camshaft are as follows: 1. Remove the intake manifold. 2. Remove the rocker arms. 3. Remove the pushrods. 4. Remove the timing chain. 5. Remove the camshaft sprocket. 6. Remove the balance shaft drive gear. 7. Remove the fan, radiator, and condenser. 8. Store the lifters in a labeled box. 9. Remove the lifter retainer. 10. Extract the lifters from the bores using a special tool, magnet, or your fingers. 11. Remove the camshaft retainer plate. 12. Use three 6-inch long, 5/16-18 bolts as a handle to remove the camshaft from the block.

It is important to keep all lifters separated and identified for reinstallation. After cleaning each lifter individually, inspect for any nicks or gauges, as any damage necessitates replacement.

Various methods can be used to extract the lifters from the bores, depending on the specific situation and available tools.

Lifters can be extracted using a special tool, a small magnet, or a machinist's scribe. Caution is advised against using pliers unless replacing the lifters, as they may damage them.

Coat the camshaft with clean engine oil and place it in the correct position in the cylinder head, then install the camshaft holding tool.

To determine the extent of cam lobe wear, 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. Then, mount a dial indicator on the engine, position the plunger against the top of the first pushrod, and zero the dial indicator. 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.

When reinstalling used lifters, ensure they are placed back in their original bores, soak new lifters in oil to remove trapped air, and coat all lifters with moly-base grease or engine assembly lube before installation.

The procedure is for removing lifters from an engine.