To remove the exhaust manifold, first disconnect the cable from the negative battery terminal and, for 4WD models, remove the front driveshaft. Next, remove the nut and move the power brake booster vacuum hose support bracket. Raise the vehicle and support it securely on jackstands. Apply penetrating oil to the exhaust pipe-to-manifold studs and nuts, as they are often corroded or rusty, and also to the EGR pipe fitting on the left exhaust manifold. Remove the nuts retaining the exhaust pipes to the manifolds, and on the left side, remove the nut and bracket securing the oil dipstick tube. For 2005 and later Expedition/Navigator models, lock the steering column in the straight-ahead position and disconnect the lower steering shaft bolt to allow moving the shaft aside for the left exhaust manifold removal. Remove the EGR pipe fitting from the left exhaust manifold and the eight mounting nuts from each manifold, noting that these nuts are difficult to access, requiring a flex-socket and various-length extensions. Before installation, check the exhaust manifolds for cracks and ensure the bolt threads are clean and undamaged, with clean mating surfaces for the exhaust manifold and cylinder head. Position a new gasket and slip the exhaust manifold over the studs, then install the mounting nuts. Tighten the nuts from the rear to the front, alternating between top and bottom rows, in three equal steps to the specified torque. The remaining installation steps follow the reverse order of removal, and when reconnecting the EGR tube to the left manifold, apply a slight amount of anti-seize compound on the threads. Finally, start the engine and check for exhaust leaks.
