How to Replace Hydraulic Liftersby Richard Rowe
Replacing a set of lifters in an engine like the classic Chevy V-8 is one of those automotive rites of passage that every mechanic has to go through at least once. Lifter replacement isn't particularly difficult from a technical perspective -- but it does require unbolting large chunks of your engine and reaching elbow-deep into its belly. Opportunities for small mistakes are many, but a slow, methodical and deliberate approach will see you through this rite of passage without catastrophe.
Getting to the Lifters
Do your research first, and take stock of your engine. You're going to have to remove almost everything higher than the engine block, which means removing all of the intake ducting, the intake manifold and the valve covers. On any given engine this could mean removing dozens of parts just to get to the lifters. Take plenty of time to familiarize yourself with the engine, and everything that needs to come off. Keep an assistant on hand to take notes on everything you remove, in the exact order you remove it, You can use this as a reverse checklist during reassembly. Take reference photos with your phone or digital camera if need be. Thorough, methodical preperation here will pay off later.
Remove the intake ducting, starting with the tube that runs from the filter box to the throttle body. Disconnect any tubes, lines and sensors that need to be, taking note of each as you do. Disconnect the cable to the throttle body and any electrical sensors, and unbolt the throttle body from the intake if need be. Start disconnecting lines and electrical connections from the intake, as far as you can reach them. Take notes and photos as you go. You will likely need to drain at least a gallon of the coolant out through the petcock valve on the radiator into a drain pan. Do so now.
Unbolt the manifold. Modern engines often have two-part manifolds with an upper and lower section. You'll likely need to remove the upper "plenum" section to get access to the bolts on the lower. Take your time, disconnecting any lines and sensors as need be. With the upper section off you should have a clear view of what you need to remove to get the lower section off.
Unbolt any accessory brackets and clamps from the manifold. On some engines like the Chevy, you may also need to remove the distributor. Turn your engine crankshaft with a wrench until the No. 1 cylinder is at top dead center, as indicated on the harmonic balancer. Place a reference mark on the distributor and block mount where it goes in with a paint marker. Remove the distributor cap, and place another reference mark on the rotor and the housing inside the distributor. Remove the distributor clamp, and gently pull the distributor out. Be careful with the oil pump driveshaft if it comes out with the distributor.
Check the fuel injection system to see what needs to be done with it. In most cases, you can simply unbolt the fuel rails on either side and gently pull all of the injectors out with it. This is preferred, since it means you don't need to open up the fuel system. On some vehicles there's enough slack in the fuel lines that you don't even need to do that to pull the manifold up and set it to the side. But otherwise, you may need to disconnect the fuel rails from the fuel feed line. Note in some cases, this may require a special tool.
Remove the bolts holding the lower intake to the engine. Make sure you get all of them, as they tend to hide. Attempt to lift the manifold out. If it's stuck -- and it will be -- hit it with a rubber mallet on the ends to break it free. Do not use a screwdriver to pry it up at the base, as you could damage the mating surfaces on the heads and intake.
Remove the valve covers. This may require removal of any number of things, not least of which being the ignition coils if you've got a coil-on-plug ignition. Getting the valve covers off can be surprisingly complicated on newer engines, so take your time.
Plug the oil drainback holes in the heads; plastic grocery bags twisted up and shoved in work well. Clean everything off with parts cleaner, and scrape any remaining gasket material clinging to the intake, valve covers or heads. Dispose of the gaskets, even if they look good and reusable. There's no sense taking a risk when you're this deep in. Clean everything you can find squeaky clean except for the valvetrain. Sop up any cleaner in the intake valley and heads with shop towels.
Replacing the Lifters
Drop your new lifters into a coffee can or pot filled with engine oil. Some people do this and others don't -- it's a matter of personal preference. Really, you can accomplish the same thing just heavily lubricating them with oil before they go in. Start removing the rocker arms, and make sure to set them aside and keep them in order. Do NOT mix up rocker arms or pushrods, and keep the pushrods oriented with the right side up toward the rocker arm. These parts develop matching wear patterns over time. Mixing them up will exponentially increase component wear and cause clearance problems.
Pull the pushrods out, keeping them with their matching rockers. Most like to shoot a blast of carburetor cleaner through the pushrod holes, just to clean out any gunk built up inside. Now, finally, you can start pulling the old lifter out. Give them all a spray with penetrating oil and allow it to soak in for a few minutes. Start pulling them out. Some will come easy, others will put up a fight. For the stubborn ones, spray them again with penetrating oil and pull them out with a set of locking-jaw pliers. Remove all of the lifters, and clean the bores out with parts cleaner on a shop towel until they're squeaky clean.
Wrap a green scrubby pad around your finger, and twist it around inside each of the lifter bores. Move up and down as you do, sanding the inside of the bores for about 10 seconds each. This is always good policy not just because it makes installing the new lifters easier, but because it slightly hones the bores and allows the new lifters to establish an even wear pattern. Wipe them out with a rag soaked in parts cleaner when you're done.
Note: If you've got flat-tapped lifters, you should replace the camshaft as well. You can generally get away with mixing new roller lifters and an old cam or vice versa, but flat-tappet cams and lifters establish matching wear patterns like the valvetrain. Mix old and new flat-tappet parts, and the entire assembly will wear out in fairly short order.
Drop the new lifters in. Between the oil and the bore sanding, they should drop in with little more than gravity. Install the pushrods. Dip each of them into oil as you go, again making sure you install them with the right end up. Install all of the rockers, again dipping them in oil as you go. For now, just install the rocker nuts or bolts with your fingers without tightening them down. When you've got them all in, push down on the pushrod side to collapse any lifters filled with oil. Rotate the engine twice with your wrench, and bring it back to top-dead-center on cylinder No. 1.
Slide a feeler gauge between the rocker arm and valve stem on the No. 1 intake valve. Typically you'll use about 0.10-inch clearance, but it varies by the engine. Tighten the rocker arm down to the specified torque and lock it in place. Repeat on the exhaust valve. Continue doing this in the engine's firing order, turning the crank a little after each cylinder until both valves are closed on the next cylinder. You have to set the clearance with the valves closed and the rockers all the way up. Double check your clearances and torque settings.
Start putting everything back together in the precise reverse order of removal. This is where the checklist notes you had your assistant take along the way will make the difference between a frustrating nightmare and a smooth, hassle-free assembly. Those notes make all the difference. Start with the valve covers, using the appropriate gaskets and sealants. Follow with the coils and wires, if necessary. Then the lower intake, the fuel rails and injectors
Return the crankshaft position to top dead center according to the harmonic balancer before reinstalling the distributor. Once it's precisely on the TDC mark, install the distributor. Use the reference marks on the distributor rotor and body line things up precisely the way they came off. Close isn't good enough here -- it has to be exact. Put everything back together from the intake to the airbox, following your notes and reference pics precisely to reconnect every sensor, line and tube. Torque them all to the manufacturer specs.
Cross your fingers, and have your assistant start the engine. Pay very, very close attention to the sounds it makes, and look for any potential leak areas around the intake and valve covers. If you did everything right, it should run perfectly. Expect a bit of lifter tap and noise initially; it should fade quickly. If the lifter tap persists for more than a few seconds, something may have gone wrong. Keep a close eye on your oil pressure, particularly if you had to remove the oil pump driveshaft under the distributor.
Top the coolant system up per the manufacturer reccomendations. Allow the engine to idle up to temperature. Pay close attention to the intake manifold gasket where the water passage meets the head. After the engine has reached operating temperature, allow it to idle for another minute, then shut it down and allow it to sit for a few minutes. Check the oil. You're looking for signs of water in the oil, indicating the manifold gasket may not have sealed.
Top up and bleed the air out of your cooling system. Change the engine oil and filter to remove anything that might have gotten in there while you were working.
- If the engine won't fire at all on the first attempt, snarling and popping and backfiring through the intake and exhaust, check your distributor. Installing the distributor "180 degrees out" is a common mistake. The No. 1 cylinder hits TDC twice in its four-stroke cycle, and you've got a 50-50 chance of installing the distributor on the wrong TDC alignment if you do so after the valve covers are on. Ideally, you'd leave the one valve cover off to make sure the valves are closed on the TDC alignment when you install the distributor -- that way you know it's not 180 out. But that may mess up your reassembly checklist order, which opens the door for mistakes. Many will take the 50-50 chance, go in order and remove and reinstall the distributor afterward if it ends up 180 out. The alternative is installing the valve cover after the distributor. It's your choice; but check the distributor if the engine chugs and backfires instead of starting the first time.
Items you will need
- Repair manual for your engine
- Full set of sockets
- Full set of wrenches
- Full set of screwdrivers
- Required pliers
- Drain pan
- Marker pen
- Rubber mallet
- Gasket scraper
- Penetrating oil
- Adjustable pliers
- Parts cleaner
- Abrasive scrubby pad, green
- Feeler gauges
- Torque wrench
- Required gaskets and sealants
- Engine coolant