The hydraulic lifter has a main cylindrical body with an internal plunger. When it fills with oil it uses pressure to automatically adjust for zero valve lash, which keeps all the valves opening and closing in perfect timing. The camshaft rotates to move the lifter, which forces pressure on the push rod. The push rod connects to a spring, which instantly forces the valve shut. Not too much can wrong with hydraulic lifters except for normal wear, and then they need to be adjusted. You can adjust the valve lash in your Pontiac without resorting to an auto repair shop.
Instructions
1. Place the vehicle in park or neutral and set the emergency brake. Raise the hood and prop it open. Leave the battery connected. Make sure the engine has warmed up but is just beginning to cool off. Note the components that sit above the valve cover or, on V-8 or V-6 engines, the valve covers.
2. Use a socket and wrench to loosen and remove the bolts or screws securing the air box hose; the plastic engine cover, or plenum; the PCV valve and hose; the throttle cable; the vacuum hoses; and any component impeding access to the valve cover. Refer to your owner's repair manual for these components, their fastener types and locations. Make note of the adjustment setting on the throttle linkage so that you can reinstall it properly.
3. Use a socket and wrench to remove the valve cover bolts on the engine. For V-6 and V-8 models, remove only one valve cover at a time to perform the procedure. Keep the bolts in order; remember their hole location and any bracket that they held. Pull the valve cover off the engine. Be sure not to damage the valve cover gasket. Start at one end of the engine and place a tappet clip on the first rocker arm tappet.
4. Fasten the tappet clip around the tappet so the oil plug fits into the tappet oil hole. You may fit the rest of the rocker arm tappets with clips, to keep the oil spray to a minimum. Start the engine. Starting at the first rocker arm tappet, loosen the locking nut on the rocker arm with an end wrench, just enough to back it off. Keep the end wrench secured around the lock nut.
5. Use a large flat-head screwdriver to turn the adjusting screw counterclockwise just until you hear the rocker arm begin to clack. Turn the adjusting screw clockwise 1/4 turn and hold it while you tighten the locking nut clockwise -- this seats the hydraulic lifter to 0 lash. Perform the identical procedure on the next rocker arm. After you have moved halfway down the bank of the engine doing the adjustments, remove the tappet clips to let the rocker arm shaft lubricate for a minute, then replace them.
6. Remove the second valve cover if you have a V-6 or V-8 and perform the same procedure. When finished with the adjustments, shut the engine off and remove all of the tappet clips. Wipe down any sprayed oil on the gasket. Replace the valve cover and insert the bolts. Tighten the valve cover bolts firmly and evenly with a socket and wrench.
7. Clean any sprayed oil on the exhaust or intake manifold with carburetor cleaner and a rag. Insert the bolts and screws onto any components you removed above the valve covers and tighten them with a screwdriver or socket. Start the engine and let it run. Some oil smoke will be normal; it will eventually burn off.
Tips Warnings
If your Pontiac has solid lifters, as with the older engines, use a feeler gauge to adjust the rocker arms. Refer to your owner's repair manual for the proper valve clearance, indicated in thousandths of an inch. Loosen the locking nut and insert the feeler gauge blade between the rocker arm and spring. Turn the adjusting screw until you have sufficient drag on the feeler gauge, then tighten the locking nut.
