Cummins ISL-G Spark Plug Change

BusTekHub Cummins ISL-G Spark Plug Replacement

Specs:

⇒Engine: Cummins ISL-G
⇒Displacement: 8.9
⇒Fuel: CNG / LNG
⇒Rating: 280Hp /320Hp
⇒Spark Plug: Cummins IR-3 4937472 (Cummins Part#4955850) includes spark boot.
⇒Spark plug gap: Pre-gapped from factory, do not adjust
⇒Spark plug torque: 28 ft-lb. (38 Nm.)
⇒Spark plug service interval: Replace every 22,500 mi. (36,000 km.), 1500 Hours or 18 months

 


 

Parts:

Spark Plug: Cummins IR-3 4937472 (Cummins Part#4955850) includes spark boot.
Alcohol pad or swab for cleaning spark plug porcelain.

Spark Plug Parts
Spark Plug Parts

 


 

Tools:

⇒General socket set, for coil removal.
⇒Ratchet
⇒Extension
⇒2 – 5/8 spark plug sockets. One socket to remove old plug, second socket for installing new plug only.
⇒Torque wrench
⇒Blow gun

Cummins ISL-G Tune-up Tools
Tools

 


 

Safety:

⇒Prior to working on vehicle, turn off batteries or disconnect battery ground.
⇒Wear proper protective equipment.
⇒Follow manufacture’s recommended service and safety procedures.
⇒This instructional article is a supplement to the manufacture’s service procedures.

 




Procedure

Removal:

1. Disconnect coil connectors.

Cummins ISL-G Coil Connector
Coil connector
Cummins ISL-G Coils
Disconnect Coils

 

2. Remove coil bracket hold down bolts

Cummins ISL-G Coil Bracket
Coil Bracket Install

 

3.  Remove coil bracket straight up, do not wiggle to remove. Wiggling coil bracket could damage coils. Cylinders 4, 5 and 6.

Cummins ISL-G Coil Bracket Coil Removal
Coil Removal Cyl. 4, 5, and 6
Cummins ISL-G Coil Bracket Coil Removal
Coil Removal Cyl. 4, 5 and 6

Removal Cylinders 1, 2 and 3. Pull straight up to clear alternator.

Cummins ISL-G Coil Bracket Coil Removal
Coil removal Cyl. 1, 2 and 3
Cummins ISL-G Coil Bracket Coil Removal
Coil Removal Cyl. 1, 2 and 3

 

4. Blow out spark plug cavities to prevent debris and dirt from falling into engine cylinder.

Cummins ISL-G Blowing Out Spark Plug Hole
Blowing Out Spark Plug Hole

 

5. Remove all spark plugs using spark plug removal socket.

Cummins ISL-G Spark Plug Removal.
Spark Plug Removal.

 

Installation:


1.
Prior to installation spark plug porcelain must be wiped down with alcohol pad or swab. Dirt, oil, and fingerprints reduce the seal strength between the spark plug boot and the porcelain causing reduced spark plug life.

Cummins ISL-G Wiping Spark Plug
Wiping Spark Plug

 

2. Install new spark plug boots to coils, new boots come with dielectric grease from the factory. If boots do not have dielectric grease, apply a small amount.

Cummins ISL-G Coil Boot Install
Coil Boot Install
Cummins ISL-G Coil Boot Install
Coil Boot Install

 

3. Install new spark plugs using clean install spark plug socket. Do not use removal socket, this will contaminate porcelain on spark plug. Torque spark plug to 28 ft-lb (35 Nm).

Note: Failure to torque spark plugs will result in engine misfire and premature spark plug failure. 

Cummins ISL-G Spark Plug Install
Spark Plug Install
Cummins ISL-G Spark Plug Torque
Spark Plug Torque

                      

4. Install coil brackets and torque to 80 in-lb (9Nm).

Cummins ISL-G Coil Bracket Install
Coil Bracket Install

 

5. Inspect coil connector pins for spreading or damage, repair if necessary.

Cummins ISL-G Coil Connector
Coil Connector

 

6. Reconnect coils.

Cummins ISL-G Connect Coils
Connect Coils

 

7. Turn batteries on or re-connect ground and start engine.

 

8. Verify no engine misfire and road test vehicle.

 

 

2 Comments on “Cummins ISL-G Spark Plug Change

  1. Hello again was wondering on torque the spark plug to 28ft lbs do you factor the 4 inch extension or no? Or what size extension do you use? Thank n you!

    1. Greetings Chris,
      a 4 inch extension will not affect the torque of the spark plug. The flex of the extension is very minimal at this torque level. I’ve done many spark plug changes on the Cummins L-gas and the Cummins ISL-G engines using a 4 inch extension, and have never had any issues. The problem I saw, was under torqueing of the spark plugs, because of Mechanics not using a torque wrench. This resulted in misfire codes and damage to the spark plugs. I use 3/8 drive extensions and sockets for spark plug changes. And on a final note, make sure your torque wrench is calibrated. After time the calibration can go off. Hope I answered your questions, and great to hear from you again.
      Best regards,
      BusTekHub

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