To remove the intake manifold, first remove the heater/ventilation inlet air ducting from the rear of the engine compartment by rotating fasteners counterclockwise and removing the cabin filter cover, filter housing, and inlet ducting. Depressurize the fuel system, disconnect the negative battery terminal, and remove the
Fuel Rail and injectors. For M56 engine models, special tools and expertise at a BMW dealership may be required for fuel rail removal. Open the jump-starting connection point and disconnect the starter motor supply lead. Disconnect the VANOS solenoid wiring connector, the breather hose from the valve cover, and the hose on the base of the tank venting valve. Release any wiring harnesses from retaining clips on the manifold and support bracket. Cut off the hose clamp on the power brake booster vacuum hose above the manifold and disconnect the plastic tube from the rubber hose. Remove the nuts securing the manifold to the cylinder head and the nut securing the manifold support bracket to the cylinder block, and withdraw the manifold while feeding the starter motor cable through it. For M54 engines, disconnect the fuel pressure regulator vacuum hose and recover the seals. Check and replace seals if necessary, and then install the manifold following the reverse of removal.For the exhaust manifold, follow similar steps to remove the heater/ventilation inlet air ducting as mentioned earlier. Raise the front of the vehicle and support it on jackstands, remove the engine splash shield and the front axle reinforcement plate/bar bolts. Attach an engine hoist or support fixture to the lifting eye at the front of the cylinder head to take the weight off the engine. Underneath the vehicle, remove the right-hand engine mounting with the support arm. Remove the plastic cover over the injectors by prying out plastic caps and removing screws. Trace back the wiring from the oxygen sensor and remove the nuts/bolts to separate the exhaust pipe from the manifold. Use the engine hoist to raise the engine slightly, then remove the front exhaust manifold and rear exhaust manifold while taking care not to damage the oxygen sensors. Discard the gaskets. For installation, apply anti-seize high-temperature grease to the manifold studs, replace the manifold gaskets, and tighten the manifold nuts to the specified torque. Tighten the front axle reinforcement plate bolts to the specified torque as well.