Head Bolt Torque Caterpillar C15 / ACERT Verified Factory Specs

Caterpillar C15 & ACERT Cylinder Head Bolt Torque Sequence

Factory OEM cylinder head bolt torque specifications, 5-stage torque-turn sequence, and tightening patterns for Caterpillar C15 6NZ and ACERT diesel engines.

Select Engine for Head Torque Sequence

Total Cylinder Head Bolts: 26 Bolts (3/4-16 Grade 8)

Official Factory Tightening Pattern

Center-outward spiral (Bolts 1 to 26)

Torque-Turn Spec

Step-by-Step Torquing Stages (Follow in Numbered Sequence)

Stage 1

Torque bolts 1 through 26 to 200 lb-ft (270 N·m)

Stage 2

Re-torque bolts 1 through 26 to 330 lb-ft (450 N·m)

Stage 3

Loosen bolts 1 through 26 completely (1 turn counterclockwise)

Stage 4

Torque bolts 1 through 26 to 200 lb-ft (270 N·m)

Stage 5

Turn bolts 1 through 26 an additional 90 degrees clockwise (Torque Angle)

⚠️ Master Technician Tip: Clean and blow out all cylinder block bolt blind holes with compressed air. Lightly lubricate bolt threads and under-head flanges with clean engine oil before installation.

OEM Specification Source: Caterpillar Service Information System (SIS) RENR2306 (C15 On-Highway Engine Specifications)

Cat C15 (6NZ/ACERT) 5-Stage Cylinder Head Torquing Procedure

The Caterpillar C15 utilizes 26 large 3/4-16 Grade 8 cylinder head bolts. The factory procedure includes a torque-to-yield seat-and-relax step:

Stage 1: Torque bolts 1 through 26 to 200 lb-ft (270 N·m) in numbered order.
Stage 2: Re-torque bolts 1 through 26 to 330 lb-ft (450 N·m) in numbered order.
Stage 3 (Seat Relax): Loosen all bolts 1 through 26 completely (1 full turn counterclockwise).
Stage 4: Re-torque bolts 1 through 26 to 200 lb-ft (270 N·m) in numbered order.
Stage 5: Turn all bolts 1 through 26 an additional 90 degrees clockwise (Torque Angle).

Related Heavy Diesel Engineering Tools

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

Pillar 3 →

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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: Caterpillar Service Information System (SIS) RENR2306 (C15 On-Highway Engine Specifications)

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