BMW E30 Sparkplug Replacement

Sparkplug Replacement Procedure

Changing sparkplugs on bmw e30 is very easy procedure. On BMW e30 with m20, m42, and other inline engines, spark plugs are located on the passenger side of the engine. It is recommended that you change one spark plug at the time as not to mix up wires. Remove spark plug wire by firmly grasping on the protective boot and pull. Do not pull on the wire itself as this can cause damage.

Use compressed air, or a brush, to clean dirt that might have accumulated around base of sparkplug in order to prevent it from going into engine once plug is removed. Get 21 mm, or 13/16 in, spark plug socket (deep socket with rubber sleeve) and ratchet and unfasten the plug. You might need to use socket extension as well.

Use spark plug gauge, or feeler gauge, and check the sparkplug gap. If it needs adjustment, gently bend outer electrode, by hammering outer electrode against hard rubber or wood. Gapping spark plugs on the higher end of specifications makes for stabler idle speed.

It's recommended that spark plug threads be lightly coated with motor oil - make sure that you don't get any on the electrode tip. Some people, including me, use anti-size instead. There are different opinions in DIY community about use of antisze for this application, with primary argument against it being that spark plugs can (easier) back out of the engine. My primary reasoning for using antisze is to ensure that I don't strip threads on the engine head when removing plugs.

Hand thread the plug, and then torque it to 20 - 30 Nm or 15- 22 ft.lb. Put the spark plug cable back on and repeat for all other plugs on your engine.