The Vortec engine is a GM-trademarked name for its General Motors trucks, which include Chevy and GMC. The Vortec engine creates a vortex inside the combustion chambers, which creates a better air-to-fuel mixture. The vortex inside the combustion chambers spins, creating a turbulent flow of gas as it is mixed with the air, in correct proportions -- usually 14 parts air to 1 part fuel. The engines are named for their cubic centimeter displacement so a Vortec 4200 is a 4.2-liter engine.
Locate the relay box near the driver's side fender well. Lift the cover off the box and using the diagram on the underside of the box, locate and remove the fuel pump relay. Start the engine and let it run until it stalls, to release pressure in the fuel system. Disconnect the negative battery cable using the appropriate wrench. Set it aside, ensuring that it does not touch metal.
Slide the drain pan under the radiator petcock valve. Loosen the petcock valve and allow the coolant to drain. Label all wires and vacuum lines in the intake manifold and throttle body. Unplug the wiring harness connectors. Remove the vacuum lines from the throttle body and intake manifold using the screwdriver to loosen the clamps.
Remove the throttle and cruise control cables from the throttle body using the screwdriver and appropriate socket. Set the cables aside. Remove the engine harness bracket, using the appropriate socket. Set the harness aside.
Unplug the wiring harness connector on the alternator. Remove the power wire using the appropriate wrench. Put the nut back onto the stud so you don't lose it. Loosen tension on the serpentine belt by rotating the tensioner pulley on its center bolt with the appropriate socket. Lift the belt off the pulleys. Remove the alternator using the appropriate socket.
Remove the intake manifold and its gasket. Remove the air conditioning line at the oil level indicator tube bracket nut using the appropriate wrench. Remove the air conditioning bracket bolt from the engine lift hook. Move the line out of the way. Remove the engine lift bracket.
Disconnect the ignition control module's electrical connectors using your fingers. Remove the ignition control module using the appropriate socket. Disconnect the engine electrical harness housing from the camshaft cover. Take care not to damage the clips. Disconnect the fuel injection electrical connectors. Remove the valve cover bolts using the appropriate socket, then remove the valve cover.
Clean the gasket-mating surfaces on the rocker galley, heads, valve covers and intake manifold. Position the valve cover gasket on the head. Install new rubber ignition control module seals. Position the valve cover onto the gasket and tighten the bolts to 89 inch-pounds of torque.
Reinstall the ignition control module and tighten the bolts to 89 inch-pounds of torque. Reconnect the ignition control module electrical connectors. Plug in fuel injectors' electrical connectors. Reinstall the engine electrical harness housing. Install the air conditioning line bracket and tighten the nut to 62 inch-pounds of torque.
Reinstall the engine lift bracket and tighten the bolts to 37 foot-pounds of torque. Reinstall the air conditioning line bracket to the engine lift bracket and tighten the bolt to 89 inch-pounds of torque. Reinstall the intake manifold and the rest of the parts in reverse order of removal. Tighten the intake manifold bolts to 16 foot-pounds of torque. Refill the radiator with coolant. Reinsert the fuel pump relay. Reattach the negative battery cable.
