Mopar 4621938 Valve Tappet

A noisy valve lifter can be isolated while the engine is idling by holding a mechanic's stethoscope or a length of hose near each valve, listening at the other end or by removing the valve cover and using fingers touching each valve spring retainer at a time to feel the shock if a lifter is a culprit. Potential sources of noisy lifters are dirt within the system and unlubricated, under-lubricated or low pressure oil therefore always ensure the oil contains no fuel content, the level is right, clean and is of the correct viscosity before attributing the problem to lifters. To change the lifters the intake manifold, and the valve covers should be first removed then the rocker arms, the pushrods, and finally the cylinder heads should be removed from the bloc of the engine. After unbolt the retaining plate bolts, you can raise the plate in order to get a working area for the lash adjusters, which are attached to an alignment yoke - it should also be lifted off. Lifters can be removed using this tool but in some models you can use a small magnet and fingers may also do the work and to pull them out a machinist scribe with an arrow point placed under the retainer ring will be useful. Users are warned against using of the pliers in a way that will result to damaging the lifters if they plan to replace them. It is also important to retain the lifters in a box with its label so that it can be fitted in the correct place. For inspection, clean the lifters with solvent and check for scuffing, score marks and uneven wear, in-turn check the lifter bores in the engine block if any damage found. The roller of each lifter should roll and rock freely, but not too loose, and should not display flat spots, pitting or anything out of the ordinary, and the same should apply for the camshaft. Worn lash adjusters are interchangeable with new camshafts or the original camshaft can be used if the lifters are new and in good condition. During installation of used lifters they should be reinstalled in the previous cylinder bore with the lubrication hole oriented in the upward direction, they should further be primed with oil to decrease trapped air, and it is recommended that they should be pre greased with moly based grease or engine assembly lube. What is left is to tighten the bolts on the retaining plate according to the correct torque and final step is to start the engine to see whether there are any oil leaks.

Before removing the camshafts, you have to take them off; after doing so, you can also take out the rocker arms. Losing hold of the rocker arms and valve lash adjuster that were removed should be avoided, thus it is advisable to mark each out individually to know which one goes where. Before installing use the opportunity to check the rocker arm tip, roller, and lash adjuster pocket for signs of wear; if any replace them. Each should be inspected in detail but particularly the ball-end which rubs against the rocker arm as these are prone to becoming obstructed; if there is doubt about their condition or if the engine develops 'valve-tapping' it will be wise to replace them. Prior to fitting the lash adjusters should be partly filled with engine oil and it should be noted that when the plunger is depressed, the movement should be minimal. And if there is too much of this travel increase, immerse the rocker arm assembly in clean engine oil and pump the plunger until such travel is nudged out. When filled with oil the Plunger has to move within the rocker arm, if so then the Plunger is defected and has to be replaced. Bolt the hydraulic lash adjusters and rocker arms to their standard position in the cylinder head and then replaced the camshafts. The adjusters should make 'tapping' noises in the initial times after restarting the engine after replacement. The process is to keep increasing the engine speed reiteratively from idle to 3000 rpm and back to idle for one minute; if the adjusters are noisy, as they should be, they will have to be replaced.