How to Determine Which Valve Lifter Is Making Noise

Lifters create noise when they malfunction. The first step in finding a malfunctioning lifter is determining the location of the noise. Press down on the rocker tip, inspect the push rod, adjust the rocker and eliminate any other failed or maladjusted components. When the lifter is defective internally, it does not hold hydraulic pressure, which causes loose rockers. If it has collapsed on the bottom, you can see this when testing the movement of all the rockers. Most of the time, but not always, valve lifter noise is a problem caused by improper oil change intervals.

Instructions

1

Check the condition of the oil. If the oil and filter hasnt been changed regularly between 3,000 to 5,000 miles, its possible the rockers are covered with sludge, restricting the oil return to the oil pan. When sludge is left to bake long enough, it turns very hard. This affects the lifters and valves.

2

Start the engine and allow it to warm up to operating temperature.

3

Place the tip of a screwdriver on the valve cover and place your ear on the handle to determine where the noise is coming from. Move the screwdriver along the valve cover until the origin of the tapping is found. Make a note of the location. Check both sides for additional problems. Shut off the engine.

4

Detach the battery cable from the vehicle and set it aside. Remove the valve cover using a socket or wrench as necessary.

5

Look at the valve train. If the engine is full of sludge and it covers the valve train, remove the sludge. If sludge is apparent, it may be blocking the oil return holes in the cylinder head, preventing proper engine lubrication. When this happens, oil fills the valve cover faster than it can drain into the oil pan, and the valve cover contains most of the oil -- leaving the oil pan with very little oil. If this is the case, remove the oil pan and clean it, the oil pump screen and the top valve train. Before doing this, proceed to the next step.

6

Inspect all the components for any obviously broken parts. Look at the rocker arms, push rods and springs. Grab each rocker arm and attempt to rock it, looking for excessive looseness. The rocker arms should rotate slightly horizontally but should be tight against the push rod and valve stem with no free play. Some of the lifters may be on the toe of the camshaft lobe, so bump the starter a couple of times to move the lifters off the toe of the camshaft. Again check all the rockers to see if any are loose.

7

Crank the engine over for a few seconds while you watch each rocker arms movement. Look for one or more rocker arms that has less movement up and down than the others, which signifies a stuck lifter. If some are found, make a note of their locations. Do not crank the engine more than five seconds at a time to prevent overheating the starter.

8

Place your finger on the push rod side of the rocker arm and keep a slight pressure on it. Have a helper bump the engine in short bursts as you watch and feel the push rod go down, opening the valve, then return, closing the valve. Keep your finger on the rocker and tell the helper to stop the moment the rocker comes all the way up. Have the helper bump the engine one more short burst, which places the lifter on the heal of the lobe.

9

Use a 5/8-inch socket to turn the adjuster nut in the center of the rocker arm counterclockwise and remove it. On some engines. the rocker arms are on a shaft instead of a single stud. Use a socket to remove the bolts securing the shaft, starting on the outside and moving from side to side inward, staggering the process. Lift the whole shaft off at the same time. When reinstalling the shaft, the bolts need to be torqued to factory specs, which are available from a service manual for your vehicle.

10

Inspect the singular stud-mounted rocker for cracks and galling -- the transfer of materials between metal surfaces -- and unusual wear where it contacts the valve and push rod. Look at the shaft-mounted rocker in question for the same indications. The shaft-mounted rocker should not have any side-to-side rocking; check if the shaft is worn. If anything is found on either, replacement is the only option.

11

Pull the push rod out of the cylinder head and check it for wear on the tips and for straightness. Roll it on a smooth clean surface, which shows if its bent. Pick it up and blow any oil out of it. Look through the oil hole. If any debris has entered the push rod, it must be removed.

12

Measure the installed height of the valve spring. This confirms a weak spring, bent valve that sticks in the valve guide or a sunken valve seat, which raises the valve stem. Use the bottom depth gauge wire on the calipers. Measure a couple of valves by placing the flat part of the caliper on the valve retainer cap and extending the wire to the head. Once the height is established, measure the one in question. If the valve is lower than the rest, you have a bent valve requiring a valve job. If the valve spring is higher, it is a worn seat involving a valve job. If it is the same height, reassemble the valve train.

13

Install the push rod, ensuring it is in the concave center of the lifter. Install the rocker arm with the center fulcrum rounded side down and flat side up over the stud. Install the center adjuster nut and tighten it down clockwise. When the nut gets close to the rocker fulcrum, slow down and grab the side of the rocker that contacts the valve. Lift up the rocker tip away from the valve. Continue to tighten the adjuster nut until the tip you are holding just makes contact with the valve, then stop. Play up and down on the tip of the rocker. Tighten the nut a little at a time until all free play is gone. Turn the nut a half turn farther to seat the push rod in the lifter, then stop. It is adjusted.

14

Install the rocker shaft by ensuring all the rockers are right side up since they rotate down. Carefully lay the shaft over the mounting points and position all of the rocker tips on the valves and push rods. Before installing the bolts, all rockers must be positioned perfectly on the valve and push rod. If the bolts are tightened and one is not located properly, it bends the push rod or shaft. Install the bolts and tighten them to factory specs from the center working outward.

15

Install the valve covers if the oil was not a roadblock because of sludge. If so, clean the head of all sludge before installing the valve cover. Drop the oil pan and clean it and the oil pump screen.

16

Install the oil pan and valve covers. Fill the engine with fresh oil and add 1 pint of Marvel Mystery oil. This is old stuff, but the only thing that works well to free sticky or dirty lifters. This must be corrected first or you will just spin the wheels trying to quiet the valve train. Run the vehicle for a couple hundred miles and the noise very likely will disappear. If it hasnt, it wont go away.