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Home›Repair guides›Jacobs C-346 Engine Brake Installation on Caterpillar 3406B Engine

Caterpillar — Jacobs C-346 Engine Brake Installation on Caterpillar 3406B Engine

A Caterpillar service procedure — check it applies to your exact model before use.

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Before you start

  • EYE PROTECTION MUST BE WORN when blowing oil from bolt holes
  • Oil in holddown bolt holes is blown out to prevent engine block cracking
  • Work carefully on engines with glow plugs to avoid puncturing wire leads
  • DO NOT readjust or tamper with solenoid valve
  • engine damage could result
  • MAKE SLAVE PISTON ADJUSTMENT CAREFULLY
  • NEVER GRIND BRIDGE to obtain clearance
  • NEVER REMOVE any engine brake component with engine running
  • PAY SPECIAL ATTENTION to slave piston adjustment for maximum efficiency
  • Slave piston adjustment must be made with engine stopped and cold
  • WEAR EYE PROTECTION and do not expose face over engine area
  • Take precautions to prevent oil leakage when engine is running
  • For engines with serial numbers lower than 7FB39279, housing leveling procedure is required

Procedure

  1. Identify front (fan end) of rocker arm group
  2. Clamp Jacobs Dowel Pin Extractor on front locating pin at cylinder 1
  3. Extract dowel pin by tightening capscrews in small equal increments
  4. Lubricate end of Jacobs oil supply adapter with clean engine oil
  5. Install adapter in place of Caterpillar dowel pin, ensure proper alignment
  6. Attach tubing to blow gun nozzle and blow oil from holddown bolt holes
  7. Apply clean engine oil to threads and underside of all Jacobs studs
  8. Place rocker arm groups back on engine
  9. Replace two outside bolts with Jacobs studs and washers
  10. Install Jacobs washers marked 'A' under stud heads
  11. Fit push tubes to rocker adjusting screws
  12. Center rocker assembly and torque studs and bolts evenly
  13. Torque to 200 Ibft then 330 Ibft in 50 Ibft increments
  14. Remove Caterpillar head bolts for support bracket installation
  15. Apply clean engine oil to threads and bolt head
  16. Install Jacobs support bracket reusing Caterpillar washer and bolt
  17. Install Jacobs spacers marked 'B' on Jacobs studs
  18. Install fuel lines with new O-rings on riser end
  19. Loosen and back out slave piston adjusting screw
  20. Install brake housing carefully, ensuring oil supply adapter alignment
  21. Install Jacobs capscrew and washer through housing into support bracket
  22. Torque support bracket bolt to 200 Ibft then retorque to 330 Ibft
  23. Place Caterpillar washers on holddown studs
  24. Install Jacobs holddown nuts and torque to 60 Ibft
  25. Retorque capscrew to 47 Ibft and holddown nuts to 100 Ibft
  26. Set exhaust valves per Table 1 locations
  27. Adjust intake valve lash to 0.015 in., exhaust to 0.030 in.
  28. Adjust slave piston clearance using feeler gauge
  29. Place cover bases on cylinder head
  30. Check for interference between crossheads and casting ribs
  31. Fasten valve cover bases with Jacobs studs and washers
  32. Tighten terminal leadout assembly in spacer
  33. Install Jacobs gaskets in spacers
  34. Install spacers over valve cover bases
  35. Install Jacobs vibration-proof nuts on mounting studs
  36. Install Jacobs serrated capscrews and torque to 13 Ibft
  37. Install solenoid valve harness and clamp
  38. Start engine and allow to run 5-10 minutes
  39. Depress solenoid armature 5-6 times to fill passages
  40. Inspect installation for abnormal oil or fuel leakage
  41. Clean and install valve covers, torque holddown nuts to 13 Ibft

Tools required

  • Jacobs special Dowel Pin Extractor
  • Vernier caliper or micrometer
  • Feeler gauge
  • Jacobs solenoid socket
  • 12 pt. socket wrench
  • Air pressure tool
  • Torque wrench

Specs & torque values

  • Jacobs spacers marked 'B'
  • Jacobs washers marked 'A'
  • Rocker studs torque: 200 Ibft (270Nem) then 330 Ibft (450Nem)
  • Support bracket bolt: 200 Ibft (270Nem) then 330 Ibft (450Nem)
  • Housing holddown: 60 Ibft (81.6Nem) then 100 Ibft (135Nem)
  • Fuel line: 30 Ibft (41Nem)
  • Valve cover torque: 13 Ibft (18Nem)
  • Slave piston lash: Feeler gauge adjustment with lock-nut torque 16 Ibft (22Nem)
  • Support stud torque: 50 Ibft (70Nem)

Source: manual:011498.pdf. Figures and steps are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.