In the 2014 and earlier 4.3L V6, as well as the earlier 5.0/5.7L V8 engines, the upper and lower intake manifolds come out without the need of removing the lower intake manifold bolts. This should be done by first disconnecting the negative terminal of the battery, and draining the fuel system of pressure. Disconnect the air intake duct, the throttle and cruise control cables and take off the engine cover. Let out the coolant in the cooling system And also the drive belt should be detached. When removing the upper intake manifold, all bypass hoses should be disconnected, vacuum hoses and electrical connectors to be marked and disconnected, as well as the wiring harness to be stowed. Relocate fuel lines, remove crankcase vent hose, carb/throttle body (if using, and EVAP canister vent solenvalve. Slightly unscrew the upper intake manifold mounting bolts so as to loosen them up and remove them by hand before lifting the manifold upwards while disconnect all other connectors. For the lower intake manifold, in some models, it is necessary to remove a valve cover. Cross any drive belts and then unbolt and take off the air conditioning compressor and also the power steering pump although they are to be placed out of the way but not the fluid lines. Take off the distributor and alternator and remove the EGR pipe, and the radiator hoses. Relax the smaller lower intake manifold nuts in the opposite sequence that was used in the tightening; use a pry bar to remove the nuts if the gasket has bonded tightly. Before installation, the mating surfaces of the product must be free from contaminants: use a gasket scraper and solvent in this regard. The final step is to apply RTV sealant on the mating surfaces, aligning gaskets properly as well as placing the manifold in its right position in a way that it will not affect the gaskets. Torque the bolts in the recommended pattern and then reverse the steps in the case of disassembly. For the model year of 2018 or newer you need to turn off PCV hose, the intake will be also needed to be removed, engine wiring harnesses should be disconnected and labeled. Detach the throttle body, and all the other connectors or hoses if there are, then unscrew and pull the intake manifold gently to prevent any scratching. Scrub the surfaces properly, align new gaskets properly and place the manifold. Fasten the bolts to the required tightness and check for the passages of vacuum after the ignition of the engine.
