Chevrolet 17120090 Lifter,Valve

To identify which of the valves of an engine is accompanied with a noisy valve lash adjuster, place a hose or tubing at each intake and exhaust valve during a running of the engine then listen to the noise at one end of the hose or tubing. Otherwise, if you take off the rocker arm cover and with the engine running, touch each of the valve spring retainers; you will feel the faulty lash adjuster through the retainer as the valve seats. As Schaevitz's warning suggests however, if adjustments are correct, dirt trapped between the plunger and lash adjuster body is often the root cause. Start with the L4 rocker arm cover followed by the intake manifold; L4 engines should have the pushrod cover also removed. Turn the nut of the rocker arm counterclockwise to get the rocker arm out of the pushrod area and then remove the pushrod. In removing the lash adjusters, one can use a special lash adjuster removal tool, or even just a sharp scribe so as not to mar the lash adjuster body in any way. Retain the lash adjusters for the purpose of reassembly in their respective sites. To dismantle a valve lash adjuster, apply pressure to the top of the plunger by inserting a pushrod to remove the pushrod seat retainer, pushrod seat, and metering valve by using a small screwdriver. The following components should be taken out, namely the plunger, ball check valve, plunger spring; the ball check valve will require use of a small screwdriver to remove in addition to the spring. Check all parts for signs of wear and where possible have the complete lash adjuster assembly replaced if any defects are noticed on the ball, particularly if there are flat spots on it. Each lash adjuster should have its camshaft lobe mating surface checked for scoring, wear, or erosion, any such texture on the lash adjuster body requiring its replacement while wear in the lash adjuster bore is rare. For reassembly, place the check ball on the small hole in the bottom of the plunger, insert the check ball spring on the seat in the ball retainer and fix the retainer. After that, insert the plunger spring over the ball retainer, turn the lash adjuster body upside down and make certain the oil holes are in proper orientation to each other before flooding the compartment with SAE 10 oil. Last but not least, fit the metering valve and the pushrod seat; push the seat in place and fix it by fitting the pushrod seat retainer. They must be replaced on their original bores and their surfaces should be treated with Molykote or an equivalent lubricating alloy before reinstalling them by reversing the above process.

To isolate a noisy valve lash adjuster, place a length of hose or tubing near each valve while listening at the other end, or remove the rocker arm cover and touch each valve spring retainer with the engine idling; a defective lash adjuster will be noticeable through the shock felt at the retainer as the valve seats. The most common cause of noise is dirt trapped between the plunger and lash adjuster body. Begin by removing the rocker arm cover, then loosen both rocker arm bolts at the cylinder with the noisy lash adjuster and rotate the rocker arms away from the pushrods before removing the pushrod guide plates and pushrods. Next, take off the intake manifold and the pushrod cover. Unscrew the pushrod cover studs to remove the lash adjuster guide retainer and then the lash adjuster guide, keeping them in order if multiple guides are removed. Lash adjuster extraction can be done using a special hydraulic tool, but often a small magnet or fingers suffice on newer engines without varnish buildup; a small scribe may also help, but avoid using pliers unless replacing the lash adjuster to prevent damage. Store the lash adjusters in a clearly labelled box to ensure they are reinstalled in their original bores. Replacing a worn lash adjuster is generally easier than repairing a defective one, as internal components are not sold separately. If cleaning a dirty lash adjuster, disassembly may restore normal function. When installing, ensure lash adjusters are placed back in their original bores, coating each foot with moly-base grease or engine assembly lube, and lubricate the bearing surfaces of the lash adjuster bores with engine oil. Install the lash adjusters with the oil orifice facing the front of the engine, followed by the lash adjuster guides and retainers. Reinstall the pushrods, guide plates, rocker arms, and retaining bolts, ensuring each pair of lash adjusters is on the base circle of the camshaft before tightening the bolts to the specified torque. Finally, reinstall the pushrod cover, intake manifold, rocker arm cover, and air cleaner.

A noisy lash adjuster can be isolated while the engine is idling by holding a length of hose or tubing against each valve and listening at the other end or removing the rocker arm cover and feeling for shock on each valve spring retainer if a valve adjuster is bad. If adjustment is correct, one of the reasons for noise is dust between the plunger and the adjuster body. For one, locate and take off the rocker arm cover as well as the intake manifold, and next on, loosen the rocker arm nut and swivel the rocker arm in an anti-clockwise direction until you can pull out the pushrod. To remove the adjuster, one is encouraged to use a special hydraulic tool called the adjuster removal tool or utilize a scribe to push the adjuster upwards but not apply any tool on the outside will damage it. Return the adjusters to their original positions for replacement; it is often easier to install a new adjuster than to repair a defective one due to the fact that internal components of an adjuster are not available in the market. Still, some degenerative adjusters may return to normal operation by disassembling and cleaning the dirty ones. During the installation of the adjusters, the latter must be replaced in their original bores and must be lubricated using moly-base grease or engine assembly lube for additional measures, while the rest of the steps is to follow the reverse procedure of removal.

Lifters should be replaced if the roller body or plunger is defective. Conditions warranting lifter and camshaft replacement include pits or roughness on either the roller body or plunger, as this can lead to lifter and camshaft damage.

Clean the lifters with solvent and check for wear. If the base is concave or damaged, replace the entire set.

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, valve covers, rocker arms, pushrods, timing chain, and cylinder heads, along with the radiator, air conditioning condenser, and camshaft position sensor.

After removing the camshaft, inspect the bearing journals for wear and damage. Measure the bearing journals with a micrometer to check for excessive wear or out-of-round conditions. Also, check the camshaft lobes for discoloration, score marks, chipped areas, and uneven wear.

After installing the camshaft, you should install the thrust plate and tighten the bolts. Reinstall the oil pump drive.

The remaining installation steps follow the reverse order of removal.

If the lifters are to be reused, they must be stored in an organized manner. They should be cleaned and dried, examined for wear or damage, and the entire set should be replaced if any lifter is worn concave, scratched, or galled.

Measurements of the diameter of each camshaft journal and the lift of each camshaft lobe should be taken using a micrometer. These measurements should be compared with the specifications to determine if they fall within the specified values.

After installing the camshaft, you should install the thrust plate and tighten the bolts. Reinstall the oil pump drive.

Stuck lifters may be freed by applying carburetor cleaner around the body and moving the lifter up and down.