Glow Plugs — Checking, Removing and Installing (BMW 7 Series E32)

If you have difficulty starting the engine, you should first check the compression in the engine. If it is too low, the engine will not start at low temperatures.

Caution: The DDE control unit is equipped with a fault code memory that stores fault codes for the electrical part of the fuel injection system. A specialist workshop can read the fault codes using a diagnostic tool and then erase them from the memory.

Checking glow plugs

Remove the engine covers and the boost pipe above the glow plugs.



The spark plugs are located under the intake ports.



Unscrew the nut and disconnect the wire from the glow plug.



Connect the voltage tester to the positive voltage supply point on the intake manifold, and connect the other wire to each glow plug in turn. The tester's LED lights up: the glow plugs are OK. For an accurate check, check the current consumption with an ammeter (in the workshop).



The LED does not light up, the glow plug is faulty, replace it.

Removal

Remove the intake manifold.

Disconnect wires (1) and (2), unscrew the glow plugs and check them visually.

Installation

Lubricate the glow plug threads with high-temperature copper-based paste. Screw in the glow plugs. The tightening torque is

Caution: The tightening torque must not be exceeded, otherwise the O-ring between the glow rod and the threaded part may become deformed.

Connect the wires to the glow plugs and tighten the nuts to 5Nm.

Install the intake manifold on the cylinder head and tighten its mounting nuts to 25 Nm, replace all gaskets. Install the oil filter housing support and the exhaust gas recirculation system pipe on the intake manifold and tighten their fasteners to 25 Nm.

Install the engine covers and boost pipe over the glow plugs.

Glow plugs with burnt rods

Burnt glow plug rods often cause damage to the injectors.



If such glow plugs (arrow) are detected during diagnostics, it is not enough to simply replace them. It is necessary to check the injectors for jet shape, uniformity, pressure and density in the workshop.