Q: How to Remove and Install Exhaust Manifolds in 3.8L V6 engine on 1997 Pontiac Grand Prix?
A: There is always time when working with cars and having to take out some of the exhaust system fasteners can be so much of a challenge since they are quite tight and in most cases this is because they have been frozen in the heating and cooling cycles that they are subjected to. Before removal, apply penetrating oil on all the threads of the exhaust manifold and exhaust pipe fasteners and let it to sit for some time. Start by removing one of the negative batteries as it allows for the notional disablement of the Theft-lock audio system if it is installed. From the front manifold to be removed includes the cooling fan to allow easy access and the mass airflow sensor, air duct, crankcase ventilation pipe if needed depending on the model, the engine mount struts and the acoustic cover for 1996 and beyond models. Disconnect the manifold from the crossover pipe, get rid of the dipstick tube hold-down nut, solve the front spark plug wires, get rid of the exhaust manifold heat shield if any. Last but not least, you can unfasten as well as pull out the exhaust manifold. As to the removal of the rear manifold, again make the battery connection off, drain the coolant, and also remove the mass airflow sensor connector, air duct, crankcase ventilation pipe if necessary. Nuts securing crossover pipe to rear exhaust manifold have to be loosened, spark plug wires have to be disconnected from rear spark plugs, and EGR pipe, transaxle dipstick tube if interfere with the access must be also removed. Disconnect the power steering pump from the upper hose, the alternator support bracket should also be unbolted and removed, the heater hoses and coolant tubes near the exhaust manifold should also be disconnected. Take off the exhaust manifold heat shield and engine lifting bracket; pull the IAC wiring off the throttle body; engage parking brake; block rear wheels; securely jack up front of vehicle using jackstands. Below the vehicle, unbolt the two exhaust pipe to manifold bolts, then turn off the oxygen sensor 8 electrical connector at the rear manifold and remove the oxygen sensor to avoid damages when removing the manifold. Last but not the least, unfasten the six bolts that attaches the manifold with the head. Cleaning learning the mating surfaces, check warp and cracks the manifold and cylinder head, resurface the manifold if the gasket was blown. Set the manifold into position with a new gasket in place and fasten the bolts loosely, then, in separate sequences tightened to the specified torque, from the centre outwards. The process of reinstalling is done in the reverse order, start the engine then to check there is no exhaust leaks on the manifold head gasket and on the manifold to exhaust pipe connection.