Replace Hydraulic Lifters
Hydraulic lifters can deteriorate from wear and tear or the buildup of contaminants and sludge in the engine oil. Lifter springs become weak or no longer travel their full path to return the valves to the closed position. The telltale clacking sound made by intake or exhaust valves is evidence of worn hydraulic lifters and should be checked immediately. New lifters can make an engine run smoother and quieter, and lifters are inexpensive and reasonably simple to replace with some mechanical experience and the right tools.
1. Clear the upper engine area of obstructions such as air ducts and wires to allow the removal of the parts. Remove any linkages and electrical connections from the intake manifold and distributor. Remove the bolts from the outer lip of the valve covers, using a wide, flat bladed tool such as a scraper to pry the valve covers loose. Bring the engine to the top dead center position by using the timing mark and observing the rocker arms for the number 1 cylinder. At top dead center, both valves will be fully closed. Remove the intake manifold bolts noting any differences in length and location. Diagram any differences to make re-assembly easier. Pry the edge of the intake upwards to loosen the manifold using caution not to damage the cylinder head surfaces.
2. Lay a couple of rags in the open cavity below the intake manifold to catch debris and then carefully clean the old intake manifold gasket materials off of the cylinder heads. Use a gasket scraper to remove heavier materials. Use solvent and a wire brush to remove lighter materials if necessary. Ensure no material is left and that the head surface is polished. Clean the valve cover gasket surfaces as well.
3. Loosen the rocker-arm retaining nuts until the rockers can be turned to the side far enough to free the push rods. Remove each push rod and inspect for damage or wear. Ensure the oil passage through the center of the rod is clear. If the rods are different lengths, note their order when they are installed. Use a strong magnet to remove each hydraulic lifter from its passageway.
4. Install the new lifters by dropping them in to the lifter passages. Ensure they are all able to turn 360 degrees freely in their passages. Reinstall the push rods and place the rocker arms over the top of each, and tighten the rocker nuts until they are in contact with the valve step but there is play in the rocker arm. With the engine still at top dead center tighten the rocker nuts for the number 1 cylinder until there is a .010 gap between the rocker arm and the valve stem. Bring the engine to top dead center for the next cylinder in the firing order and tighten the rocker nuts until there is a .010 gap between the valve stem and the rocker. Repeat this for each cylinder until you return to number 1. Re-check the clearance on number 1 again when it returns to top dead center, then re-check the clearance for the rest following the firing order again.
5. Install the new gasket for the intake manifold with gasket sealer around any water passages. Replace the intake and torque the bolts to the manufacturers specifications. Reinstall any linkages, fuel lines or electrical connectors that the engine needs to run. Install the valve covers lightly in place without the gaskets and with only one or two bolts each. Start the engine and let it warm up; listen carefully for any ticking or clacking that does not smooth out once the engine oil pressure climbs.
6. Shut down the engine and remove the valve covers. If the engine was noisy, re-check the valve adjustments for each cylinder and restart the engine. If the engine was smooth and quiet, remove the valve covers and install the gaskets. Replace the bolts and tighten to the manufacturer’s specifications. Reattach any additional engine accessories, connectors or linkages and start the engine. Check carefully for oil of coolant leaks and watch the engine temperature before the first test drive.