Replacing spark plugs (petrol engines) (BMW 5 Series E39)

The following special tool is required:

• A 16mm spark plug wrench, which is included with the standard tool kit or can be purchased inexpensively at stores selling accessories for motor vehicles.
• 10mm socket wrench.

The following parts are required for replacement:

• Standard spark plugs.

Removal

The engine must be allowed to cool until it is warm to the touch.

Remove the ignition coils.

Unscrew the spark plugs with a wrench and check their condition (the so-called "face of the spark plug"). With some experience, you can draw conclusions about the operating condition of the engine based on the results of the inspection.

Installation

Clean the threads on the spark plugs with a clean cloth.

Screw the spark plugs into the cylinder head by hand until they stop.

Attention: Do not twist the candles at an angle when screwing them in.

Tighten the spark plugs to a torque of 25 Nm.

Caution: If a torque wrench is not available, tighten new spark plugs by 90° (¼ turn), tighten used spark plugs by approximately 15°. Spark plugs that are tightened too much may strip or damage the threads in the cylinder head when unscrewing. In this case, the spark plug threads must be repaired using UTC or Heli-Coil inserts.

Install the ignition coils and engine cover, making sure they are seated correctly spark plug tips and mass jumpers.

The original source of the article is on the website «BMWMan»