GL550 2012 If you search the forums for this exchange job you will be told all sorts of horror stories such as: B. removing the engine mount and/or the exhaust manifold. That is unnecessary. Disconnect the battery! Remove the heat shield (3 bolts near the catalytic converter) and the heat shield on the starter (unscrew the two 10mm nuts and remove the heat shield). slightly and remove the black cap from the magnet positive lead. This leaves clearance for the starter to oscillate. Then disconnect the wires.