CAT Engine Overhead Adjustment Calculator
Use this CAT Engine Overhead Adjustment Calculator to find correct valve lash, torque specs, and Jake brake settings for your Caterpillar diesel engine
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CAT Engine Overhead Setup Calculator
⚠️ CRITICAL SAFETY NOTICE: This calculator provides REFERENCE VALUES ONLY based on common industry specifications. These are NOT verified for your specific engine and may be INCORRECT.
Jake brake slave piston lash values shown are typical for common Jake models (340 series, etc.) but vary by Jake generation, production year, and ESN range. Some engines use IVA (Intake Valve Actuator) or integrated Cat Compression Brake with different specs.
YOU MUST verify ALL specifications (valve lash, Jake brake clearance, torque values, procedures) via your engine's ESN using Caterpillar SIS, Jacobs Vehicle Systems documentation, official service literature, or an authorized Cat dealer before performing ANY work.
LubeGuide.org, Vyscocity.com, Dawn Inc., and their affiliates assume NO LIABILITY for engine damage, personal injury, or any other consequences resulting from use of these reference values. By using this tool, you acknowledge that you assume all risk and responsibility for verifying accuracy. Not affiliated with Caterpillar Inc. or Jacobs Vehicle Systems.
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FAQ
What is the valve lash for a CAT C15?
CAT C15 (non-ACERT) engines typically require 0.015 inches intake and 0.030 inches exhaust valve clearance when cold. Jake brake slave piston clearance is typically 0.027 inches, though some units with IVA (Intake Valve Actuator) may be 0.020 inches. Always verify specifications using your engine’s ESN with Caterpillar SIS or Jacobs documentation.
How do I adjust CAT 3406E valves?
CAT 3406E valve adjustment uses the two-position method: Set cylinder 1 to TDC compression, adjust specific cylinders per firing order, rotate crankshaft 360 degrees, then adjust remaining cylinders. Use feeler gauges set to 0.015 inches (intake) and 0.030 inches (exhaust) when cold. Jake brake slave typically 0.027-0.030 inches. Torque valve locknuts to 55 Nm (41 ft-lb). Always verify via ESN.
Should I adjust CAT engine valves hot or cold?
Most CAT on-highway diesel engines (C15, 3406E, C13, etc.) specify valve adjustment when cold. Always verify the correct temperature for your specific engine model and serial number, as some industrial or marine variants may differ. Consult Caterpillar SIS for your ESN.
What is the torque spec for CAT valve adjuster locknuts?
Typical CAT valve adjuster locknut torque is 55 Nm (41 ft-lb) for larger engines like C15, 3406E, and C13. Smaller engines like C7 and 3126 use 42 Nm (31 ft-lb). Jake brake locknuts are typically 35 Nm (26 ft-lb) for large engines. Always verify for your specific ESN via Caterpillar SIS.
What is Jake brake slave piston clearance on a C15 ACERT?
C15 ACERT Jake brake slave piston clearance typically ranges from 0.027 to 0.034 inches, depending on production year and Jake model. Some ACERT engines have integrated Cat Compression Brake with different specs. Always verify via Caterpillar SIS and Jacobs Vehicle Systems documentation for your specific ESN.
Do C12 and C13 engines have different Jake brake specs?
Yes, C12/C13 Jake brake slave clearance is often 0.034 inches, though some units may specify 0.055 inches (1.40mm). The variation depends on Jake brake model and serial number range. Always check your specific ESN via Caterpillar SIS.
Hot means the engine has been run to normal operating temperature, oil is warm, and metal components have expanded. Hot lash specs are sometimes different from cold specs because heat changes clearances.
Most CAT overhead settings are specified as cold in service manuals, unless otherwise noted. Always confirm in the manufacturer’s procedure.
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