Replace a leaking head gasket at the first sign of failure to prevent any further damaged to engine components. On a 1999 Chevrolet Cavalier Z24 2.4-liter engine, you can replace the gasket after removing the intake manifold to access the cylinder head. While novice mechanics may find it difficult, following the guide and taking special care when removing engine components will allow you to change the gasket in a few hours.
Relieve the fuel system pressure. Remove the fuel filler neck cap and disconnect the electrical connection running to the fuel pump, located on the fuel tank. Run the vehicle until the engine stalls.
Drain the cooling system. Place a oil drain container under the drain fitting on the bottom of the radiator. Turn the drain fitting counterclockwise to drain the fluid from the radiator, using pliers if the drain fitting won't turn by hand. Tighten the drain fitting when the fluid has finished draining from the radiator.
Remove the accelerator cable, cruise control cable and throttle valve cable (on models equipped with automatic transmissions). The cables are located near the throttle body. Carefully push the cable up through the opening in the clips attached to the throttle body.
Label and disconnect the electrical connectors and hoses on the intake manifold. The vacuum and breather hoses running to the manifold will need to be disconnected. The MAP, IAT, and EVAP electrical connectors will need to be disconnected and removed. The electrical connections running to the fuel injectors will need to be removed as well.
Remove the oil fill cap and dipstick assembly. Unbolt the oil fill tube with a ratchet wrench and detach it from the engine block. Rotate it to gain clearance in order to remove it from the engine compartment.
Remove the alternator bracket bolt closest to the engine block with a ratchet wrench.
Remove the EGR pipe from the EGR valve. The EGR valve is located near the brake master cylinder and brake fluid reservoir, near the firewall on the driver side of the engine compartment. Pull the EGR pipe away from the valve to remove it.
Remove the intake manifold support brace mounting bolts with a ratchet wrench and remove the brace.
Remove the intake manifold mounting nuts and bolts with a ratchet wrench, and remove the intake manifold.
Remove the cylinder head bolts with a ratchet wrench. Label the cylinder head bolts upon removal, as they must be installed in the same location. Remove the cylinder head.
Clean the mating surfaces of the cylinder head and engine block. Remove the old gasket and clean off any remaining material with a gasket scraper. Soak a towel with lacquer thinner and thoroughly wipe both mating surfaces until no debris is left on either surface.
Place the new head gasket over the dowel pins and place the cylinder head on the engine block. Finger-tighten the cylinder head mounting bolts. Working from the center bolts outward, tighten the bolts with a torque wrench to 40 ft.-lbs., except for the two bolts on the edge of the cylinder head near the front of the engine, which should be tightened to 30 ft-lbs. After the bolts are tightening to the correct specifications, work again from the center bolts outward, tighten the bolts another 90-degree turn.
Put the intake manifold in place and finger-tighten the intake manifold nuts and bolts. Tighten the nuts and bolts with a torque wrench to 18 ft.-lbs. Tighten the center bolt/nut first, then tighten the bolts/nuts directly to the left and right of that bolt. Tighten the two bolts on the edges of the manifold next, then the two bolts located on the longer side of the manifold.
Install the intake manifold support brace and replace the mounting bolts with a ratchet wrench.
Push the EGR pipe back onto the EGR valve.
Replace the alternator bracket bolt removed in Step 6 with a ratchet wrench.
Install the oil fill cap and dipstick assembly. Rotate the dipstick assembly while lowering it into position. Replace the mounting bolt with a ratchet wrench attaching it to the engine.
Connect the electrical connectors and hoses disconnected in Step 4.
Attach the accelerator cable, cruise control cable and throttle valve cable (on models equipped with automatic transmissions) that were removed in Step 3. The cables are located near the throttle body. Carefully push the cable down through the opening in the clips attached to the throttle body.
Refill the cooling system with the correct amount of engine coolant.
Replace the fuel filler neck cap and connect the fuel pump connection that was disconnected in Step 1.
Start the vehicle and check for leaks around the cylinder head.
