GMC 5234890 Lifter,Valve

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.

Finally, reinstall the valve components, valve cover, and intake manifold.

If the cam lobe lift is less than the specified value, it is recommended to install a new camshaft.

For 1986 and earlier models, the steps are as follows: 1. Remove the rocker arm covers and the intake manifold. 2. Loosen the rocker arm nut and rotate the rocker arm away from the pushrod. 3. Remove the pushrod, storing them in an organized manner if more than one is removed. 4. Use a special hydraulic lifter removal tool to remove the lifter, avoiding the use of pliers or other tools on the outside of the lifter body to prevent damage.

Loosen the rocker arm bolt and rotate the rocker arm away from the pushrod to remove it, ensuring that if more than one pushrod is removed, they are stored in an organized manner for reinstallation in their original location.

Assuming that adjustment is correct, the most likely cause of a noisy valve lifter is excessive wear at the lifter foot and camshaft lobe or wear or contamination of the internal components.