Hydraulic lash adjusters are generally reliable and do not need frequent adjustments. A noisy adjuster can be diagnosed while the engine is idling by placing a hose or tubing near each intake and exhaust valve and listening at the other end, or by removing the rocker cover and feeling for shock at the valve spring retainers. If adjustment is correct, noise is often caused by dirt trapped between the plunger and adjuster body. To remove the adjusters, take off the intake manifold and pushrod cover, then remove the valve cover and lift each pushrod out. A special tool can be used to pull the adjusters from their bores, or a sharp scribe can be employed to push them upwards, avoiding pliers on the adjuster body. A stuck adjuster may be freed with carburetor cleaner. Keep adjusters separated and identified for reinstallation. After cleaning each adjuster, inspect for any damage, as nicks or scratches warrant replacement. Check the bottom of the adjuster for wear; a concave condition indicates it should be replaced. When installing adjusters, ensure they are coated with "Molykote" or a similar product, and if original adjusters are reused, they must go back into their original bores. Finally, reinstall the valve components, valve cover, and intake manifold.