GMC, replacing glow plugs in Zevulun

GMC, replacing glow plugs in Zevulun.
A characteristic sign of a faulty glow plug is the absence of a key click in the ignition. To replace the glow plug, it is necessary to dismantle the protective casing from the engine (if any), and other elements that facilitate access to the spark plugs. Then remove the upper casing of the cylinder head, the contact wires from the glow plug and remove the plug from the seat. After cleaning the seat, install a new plug.