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Valve Lash & Overhead Cummins ISX15 / X15 Verified Factory Specs

Cummins ISX15 & X15 Valve Lash & Jake Brake Clearance Specs

Factory OEM cold valve lash adjustment specifications, feeler gauge sizes, and TDC cylinder firing order steps for Cummins ISX15 and X15 commercial diesel engines.

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Intake Valve Lash (Cold)
0.014 in
Feeler Blade: .014 in (0.36 mm)
Exhaust Valve Lash (Cold)
0.027 in
Feeler Blade: .027 in (0.69 mm)
Engine Brake (Jake) Lash
0.070 in
Feeler Blade: .070 in (1.78 mm)

Cylinder Adjustment Stepper (Firing Order: 1-5-3-6-2-4)

Click Step 1 or Step 2 to highlight which valves to set based on crankshaft timing mark.

Step 1 of 2: Cylinder 1 at Top Dead Center (TDC)
Line up Engine Timing Mark at 'A' or '1-6 TOP' (Cylinder 1 at TDC Compression)
Valves to Adjust in this Position:Cylinder 1 Intake & Exhaust, Cylinder 2 Intake, Cylinder 3 Exhaust, Cylinder 4 Intake, Cylinder 5 Exhaust
Engine Brake (Jake) & Injector Settings:Cylinders 1, 2, 3 Jake Brake Slave Pistons (.070 in)
Rocker Arm Lock Nut Torque: 35 ft-lbs (47 N·m)
Source: Cummins QuickServe Online Service Manual Bulletin 003-004 (ISX/X15 Overhead Set)

Cummins ISX15 / X15 Overhead Setting Protocol (Cold Engine)

Timing Mark "A" (Cylinder 1 TDC Compression)

  • Intake Valves: Cylinder 1, Cylinder 2, Cylinder 4 (.014 in / 0.36 mm)
  • Exhaust Valves: Cylinder 1, Cylinder 3, Cylinder 5 (.027 in / 0.69 mm)
  • Engine Brake (Jake): Cylinders 1, 2, 3 Slave Pistons (.070 in / 1.78 mm)

Timing Mark "B" (Cylinder 6 TDC Compression - 360° Turn)

  • Intake Valves: Cylinder 6, Cylinder 5, Cylinder 3 (.014 in / 0.36 mm)
  • Exhaust Valves: Cylinder 6, Cylinder 4, Cylinder 2 (.027 in / 0.69 mm)
  • Engine Brake (Jake): Cylinders 4, 5, 6 Slave Pistons (.070 in / 1.78 mm)
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Related Heavy Diesel Engineering Tools

Cross-reference other factory specifications and diagnostic tools for commercial diesel engines:

Pillar 3 →
Valve Lash & Overhead
Intake, exhaust, & Jake brake clearances.
Pillar 1 →
Oil & Coolant Sump
Standard vs deep pan fill volumes.
Pillar 4 →
Head Bolt Torque
Torque-to-yield angle stages & sequences.
Pillar 2 →
SPN Fault Code Lookup
J1939 fault diagnostics & sensor pins.
Technical Reference Citation: Cummins QuickServe Online Service Manual Bulletin 003-004 (ISX/X15 Overhead Set)
View Engineering Methodology & Standards →