/// Mister-Auto’s DIY Guides

www.mister-auto.co.uk - 0844 338 00 21*Please note: free and informative document for which Mister-Auto does not accept any responsibility or liability.

INSTALLING SPARK PLUGS

- 1 combination spanner- 1 extension bar

- 1 plug wrench- 1 steel brush

30 mins

EQUIPMENT

DIFFICULTY

TIME

Only petrol cars have spark plugs. Spark plugs generate a small spark which is sent into the combustion chamber. Thanks to the spark, the air/fuel mixture there can ignite so that the engine starts running. A spark plug consists of an extremely heat-resistant ceramic insulator. In addition it has a number of electrodes (four at the most). The more electrodes a spark plug has, the longer its lifespan. Bad spark plugs cause a reduced fuel economy.

TIPS FROM MISTER-AUTO

• Be carefu l wi th your HT leads when dismounting your

spark plugs: to avoid pul l ing one off when

taking out your spark plugs, squeeze your fingers around

the plug terminal and twist ¼ of a turn whilst gently lifting the plug.

• It is not necessary to tighten your new plugs too much, just keep to the instructions in your owner’s manual. If your car was built after the 1990s, use a ratchet to tighten your plugs correctly.

• A newly installed spark plug doesn’t need to be tightened with a spanner but threads on manually. Generally three or four turns are enough. Remember to clean the seats and wiring with a steel brush prior to installing new spark plugs.

• Always dismount and install your spark plugs one after the other and not simultaneously to avoid making a mistake when reconnecting the wires.

Never choose your spark plugs solely on their shape. In most cases two spark plugs resemble each other like two drops of water.

The best way to select the proper spark plugs for your vehicle is by dismounting one and measuring the thread diameter, its total length and thermal indicator. Always check your owner’s manual as well. You’ll generally find exactly which type of spark plugs your car

needs there.

Another way of finding out which the right spark plugs are, is by taking the engraved reference o n t h e m e t a l s h e l l . T h i s reference will allow you to find a corresponding model. Don’t worry about brand too much, if your original spark plugs are Bosch, you can replace them without any problems with Delphis, Berus or NGKs.

HOW TO CHOOSE THE RIGHT SPARK PLUGS?

SPARK PLUGS

/// Mister-Auto’s DIY Guides

www.mister-auto.co.uk - 0844 338 00 21*Please note: free and informative document for which Mister-Auto does not accept any responsibility or liability.

CHANGING SPARK PLUGS IN 6 EASY STEPS

Remove the plug cover. Do not remove all plugs at the same time but one by one.

Step

Step

Step

Step

Step

Step

SPARK PLUGS

Take your plug wrench, put it onto the spark plug you want to remove and loosen it.

Once the plug turns freely, unscrew it manually.

Compare the old plug with the new one. It is possible that the electrode is protected by a metal cap, which needs to be removed with flat pliers.

Clean the plugs’ emplacement (avoid brushing dirt into the cylinders).

The spark plug

Take off the cover

Remove the plug

Compare the plugs

Grease your new spark plug

Screw on the new spark plug

Manually thread on the new plug in at least three turns. Finish off with your plug wrench and ratchet. Keep to your owner’s manual to avoid tightening them too much.

1

2

3

4

5

6

THE ENGINE MUST

BE SWITCHED OFF

AND COLD!