CAUTION
Spark plug life is largely dependent on
cleanliness of the plug's porcelain. Dirt,
oil, and fingerprints reduce the seal
strength between the spark plug boot

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and the porcelain causing reduced
spark plug life. Do not touch the
porcelain area on the spark plug. Use
rubbing alcohol and a lint-free cloth to
clean the spark plug porcelain and
rubber boot before installing the spark
plugs.

CAUTION
Do not clean boots on C8.3G, C Gas
Plus, L Gas Plus, or ISL G applications.
These boots are pre-greased.
A convenient option is an alcohol prep pad
that does not contain any moisturizers or
other cleaners. Compliant alcohol prep
pads are available at many department
stores, drug stores, and industrial supply
centers.
Use rubbing alcohol and a lint-free cloth to
clean the spark plug porcelain and rubber
boot.

Table 2: Final Gap Specification
Engines

Maximum Re-Use Gap
mm

in

B5.9 G-150 and 195 hp and B5.9 LPG

0.66

0.026

B Gas Plus 195 hp

0.66

0.026

B5.9 G 230hp

0.771

0.028

B Gas Plus -200 and 230hp

0.771

0.028

B LPG+

0.66

0.026

B Gas International 150 and 195 hp

0.66

0.026

B Gas International 230 hp

0.771

0.028

ISB 5.9G 230 hp

0.66

0.026

ISB 5.9G less than 230 hp

0.66

0.026

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C8.3 G and C Gas Plus

0.635

0.025

L10G Automatic Transmission

N/A

N/A

L10G Manual Transmission

N/A

N/A

CNGE (Prime Power)

N/A

N/A

ISL G and L Gas Plus

0.635

0.025

Use the following to determine if the spark
plug meets reuse guidelines. Refer to
Spark Plug Reuse Guidelines, Bulletin
4383578.
Inspect the spark plugs for the following
issues:
1.
2.
3.
4.
5.

Insulator flashover
Electrode deposits or fouling
Missing electrode
Corrosion (not shown)
Electrode beading (not shown).

A worn electrode does not mean that the
spark plug should be replaced. However,
if the electrode gap is less than the
minimum starting gap, reference Table 1. If
the electrode gap is greater than the
maximum reuse gap, reference Table 2 to
replace the spark plug.

NOTE: Spark plugs should not be
replaced due to corona staining (3).
Corona staining does not affect spark
plug or ignition system performance.
1. Cracked insulator
2. Electrode misalignment
3. Corona staining.

NOTE: If a spark plug exhibits electrode
beading, check the electrode gap

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before discarding the plug. Replace the
plug only if the gap is less than the
minimum gap shown in Table 1, in the
Initial Check section above.
A damaged spark plug showing traces of
aluminum can indicate piston damage.
Inspect the piston for damage. Use the
following procedure in the ISL G CM2180
Service Manual, Bulletin 4021649. Refer
to Procedure 001-043 in Section 1 or
contact a Cummins® Authorized Repair
Location.

Remove the old spark plug boot:
Twist the spark plug boot on the extension
one full turn, then remove the spark plug
boot by pulling and twisting at the same
time.

Clean the coil extension.
Use a clean, lint-free cloth to remove any
deposits from the outside and inside of the
coil extension.
Refer to Procedure 013-012 in Section 13
in the appropriate service manual.

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Install
Install the spark plug boot onto the coil
extension.
Install the new boot onto the end of the
coil extension by pushing and twisting the
boot at the same time until it is fully seated
on the extension.

NOTE: Do not over apply the dielectric
grease.
Verify that dielectric grease is inside the
opening of the spark plug boot.
If there is no dielectric grease in the new
boot, apply a pea-sized amount of
dielectric grease, Dupont® Krytox 205,
Cummins® Part Number 3164956, or
equivalent, to the inside of the boot.
Spread it around the inner diameter to
ease assembly on the spark plug.

WARNING
When using solvents, acids, or alkaline
materials for cleaning, follow the
manufacturer's recommendations for
use. Wear goggles and protective
clothing to reduce the possibility of
personal injury.

WARNING

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Some solvents are flammable and toxic.
Read the manufacturer's instructions
before using.

CAUTION
Spark plug life is largely dependent on
cleanliness of the plug's porcelain. Dirt,
oil, and fingerprints reduce the seal
strength between the spark plug boot
and the porcelain causing reduced
spark plug life. Do not touch the
porcelain area on the spark plug. Use
rubbing alcohol and a lint-free cloth to
clean the spark plug porcelain and
rubber boot before installing the spark
plugs.

CAUTION
Do not clean boots on C8.3G, C Gas
Plus, L Gas Plus, or ISL G applications.
These boots are pre-greased.
A convenient option is an alcohol prep pad
that does not contain any moisturizers or
other cleaners. Compliant alcohol prep
pads are available at many department
stores, drug stores, and industrial supply
centers.
Clean the magnetic spark plug socket and
spark plug.

CAUTION
Mechanical over-tightening can
damage the spark plug and cylinder
head or adapter.

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CAUTION
Proper spark plug torque is required for
heat transfer from the spark plug to the
cylinder head. Improper torque will lead
to spark plug failure, disconnected
spark plug wires, and possible engine
damage.
Inspect the cylinder head plug cavity for
debris. Clean as required.
Install the spark plug. Use a magnetic
spark plug socket, Part Number 3824876,
and thread the plug in by hand to make
sure that the threads are smooth and the
plug is not cross-threaded. Tighten the
spark plug.
NOTE: The use of anti-seize compound
on spark plug threads is not approved
by Cummins Inc.
Torque Value: 38 n.m [28 ft-lb]

Check the ignition coil.
Refer to Procedure 013-012 in Section 13
in the appropriate service manual.

For B5.9G, B5.9LPG, B Gas Plus, B LPG
Plus, B Gas International, ISB5.9 G
Applications:
Clean, add dielectric grease, and install

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the spark plug wires.
Refer to Procedure 013-014 in Section 13
in the appropriate service manual.

WARNING
Do not remove the coil extension or
engine damage could possibly result.

CAUTION
Do not clean boots on C8.3G, C Gas
Plus, L Gas Plus, or ISL G applications.
These boots are pre-greased.
For C8.3G, C Gas Plus, L Gas Plus, and
ISL G Applications:
Clean the spark plug, replace the boot,
and install the coil.
Install the ignition coil.
NOTE: For an angled coil, clean/remove
the grease deposits from the end of the
coil spring at each plug change interval
prior to installing a new plug boot onto
the coil.
Refer to Procedure 013-012 in Section 13
in the appropriate service manual.
Torque Value: 9 n.m [80 in-lb]

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For L10 G Applications:
Clean, replace the boot, add dielectric
grease,and install the spark plug wires.
Refer to Procedure 013-014 in Section 13
in the appropriate service manual.

Last Modified: 25-Mar-2015
Copyright © 2000-2010 Cummins Inc. All rights reserved.

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