Here's a general outline of the process. Specific procedures and measurements will be found in your vehicle's repair manual. You absolutely *must* have this manual; it will provide the exact specifications for your engine and year. You can usually find them online (e.g., Chilton's, Haynes) or at auto parts stores.
1. Preparation:
* Gather Tools: You'll need a valve lash adjustment tool (feelers gauges), a socket wrench set, a torque wrench (for tightening cylinder head bolts if you remove the rocker arms), jack stands, wheel chocks, and potentially a breaker bar.
* Safety First: Disconnect the negative battery terminal. Wear safety glasses.
* Consult the Repair Manual: Find the specifications for the correct valve lash clearance (often measured in thousandths of an inch or millimeters) for both intake and exhaust valves. The manual will also detail the correct firing order for your engine.
* Access: You'll need to access the valve train. This usually involves removing the valve cover(s). The repair manual will guide you on how to do this safely and efficiently.
2. Valve Lash Adjustment:
* Identify Top Dead Center (TDC): Use the repair manual to locate the TDC mark on the crankshaft pulley or harmonic balancer. This is crucial for adjusting the valves correctly. You may need to rotate the engine by hand using a wrench on the crankshaft bolt.
* Cylinder Selection: The repair manual will tell you which cylinder to work on first (usually number 1). You'll adjust the valves for that cylinder, then move to the next in firing order.
* Rotate the Engine: Rotate the engine until the piston in the selected cylinder is at TDC on the compression stroke. The repair manual will explain how to verify this.
* Adjust Valves: Using the feeler gauge, check the clearance between the rocker arm and the valve stem. Add or remove shims (if your engine uses shims) or adjust the rocker arm nut (if using adjustable rocker arms) until the specified clearance is achieved. The repair manual will explain which type of adjustment your engine uses.
* Repeat: Repeat steps 2-4 for each cylinder in the correct firing order, ensuring the piston in each cylinder is at TDC on the compression stroke before adjusting the valves.
3. Reassembly:
* Replace Valve Cover(s): Carefully replace the valve cover(s) and tighten the bolts to the manufacturer's specifications (found in the repair manual).
* Reconnect Battery: Reconnect the negative battery terminal.
Important Considerations:
* Shimmed vs. Adjustable Rocker Arms: Some 3.1L engines use shims, requiring you to remove and replace them to adjust valve lash. Others may have adjustable rocker arms, allowing direct adjustment with a nut. The repair manual will show you what kind of system your engine has.
* Firing Order: Following the correct firing order is essential; otherwise, you'll adjust the valves incorrectly.
* Torque Specifications: Always follow the torque specifications for all bolts and nuts as specified in your repair manual. Using the wrong torque can damage the engine.
Again, I strongly advise using a repair manual specific to your year and model of 3.1L Chevy Malibu. Attempting this without the proper information and experience can lead to engine damage. If you are unsure about any step, consult a qualified mechanic.
