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A 14
en
Bosch tip
Flat seat
Correct spark plug installation with torque wrench:
Conical seat
Tightening torque (N • m): 10 N • m ≈ 1 kpm
1
2
1
2
M 10 x1
10...15
10...15
M 14 x1,25
20...40
10...20
M 12 x1,25
15...25
15...20
M 18 x1,5
30...45
15...23
M 14 x1,25 l <12,7 mm 20...25
15...20
M 14 x1,25 l >12,7 mm 20...40
20...30
M 18 x1,5
20...35
30...45
Please note:
The tightening torques specified apply to dry, non-greased and non-oiled threads and
new gaskets.
For lubricated threads or reinstallation of a spark plug, the specified torques should be
reduced by 1/3.
1 in cast iron
2 in aluminum
Correct spark plug installation without torque wrench:
Please note:
Screw in spark plug by hand until it is seated in the cylinder head.
Spark plugs with flat seat and a new seal are then turned about 90° further with the
spark plug wrench.
Spark plugs with conical seat and spark plugs with a used flat seal are then turned
about 15° further.
Spark plug terminal nuts
Please note:
Engines may be fitted with spark plugs of a different length to Bosch spark plugs.
1. Screw out old spark plugs.
2. Compare to new Bosch spark plugs.
3. I f the exchanged spark plug is longer than the Bosch spark plug, replace the
screwed-on terminal nut A with the longer terminal nut B provided.
Please note!
The spark-plug recommendations are issued by Bosch, where not originating from
the vehicle or engine manufacturer. The recommended spark plugs apply to normal
­operating conditions for production models, not to racing, special-purpose or high­performance vehicles, unless specifically listed.
Use of heat ranges other than those recommended may be necessary because of
­special operating conditions. If spark plugs with the specified electrode gap are not
available, the electrode gap must be adjusted. For this, we recommend using the Bosch
spark plug gage (see page A 15).
Bosch Automotive Aftermarket
2009  |  2010