As a vehicle’s mileage increases, parts begin to wear out or need adjustment. The valve train is no exception; even the advent of hydraulic tappets has failed to eradicate the noise of the valve train. There are several possible causes for this noise, including poorly regulated valves, worn rockers, bent rods, worn valve guides, and loose screws. If inspection of all of these parts fails, the problem is likely to lie with the tappets. Before disassembling the engine and replacing them, try a few steps to silence these loud nozzles.
How to Stop the Noise of Hydraulic Tappets
Start the engine, allow it to warm up to the operating temperature, and then turn it off. Remove the dipstick from the engine. Clean it with a cloth, then insert it back into the tube and pull it out for analysis.
Inspect the oil level while the dipstick is out to ensure that the engine does not contain an excessive amount. Excess oil causes the valve control to foam, causing air bubbles in the system. If they enter the hydraulic tappets, they will not have sufficient hydraulic pressure, thus generating noise.
Inspect the oil on the dipstick for dirt, mud, solid contaminants or excess carbon content, observed by a darkening of the oil. Sludge in the sump will prevent the pickup tube from sucking the appropriate amount of oil to lubricate the engine. Change the oil and filter, if necessary. Add a bottle of penetrating oil, which breaks down the sludge in the sump and lubrication system. Lack of lubrication can cause noise in the tappets.
Remove the valve cover with any necessary tools if you cannot find the contaminants found in the engine oil. Start the engine.
Hold one end of the heating hose against either ear while you move the other end from rocker to rocker to hear the noises. Note which are the noisy rockers.
Adjust the valves to factory specifications. If they are not properly adjusted, the tappets will make noise.
Loosen the rocker nut and slide its arm to the side if the valves and tappets do not make a noise. Inspect the rods to ensure that they are aligned and are not blocked by mud. Replace any bent or clogged rods and adjust the valves again.
Remove the noisy tappets from the engine following the procedures provided in the manufacturer’s manual if you do not find defective rods. Inspect them for wear and perform a leak test on the cartridges that do not show excessive wear (see the Tips section for more details). Replace those that show excessive external wear or that have failed the leak test.
Disassemble the noisy tappets if they pass the leak test: compress the piston into the tapp, remove it from the pressure ring with specific pliers, and slowly release the spring pressure on the piston.
Remove the piston, spring, and retaining ball inside the tappet. Inspect worn or broken parts. Replace defective tappets.