How to Adjust Cam Backlash on a Caterpillar 3406E

Caterpillar is one of the foremost manufacturers of heavy industrial and agricultural machinery, equipment and vehicles in North America. The Caterpillar 3406E is a diesel engine manufactured by the company. The 3406E is a four-stroke, 14.64 liter engine. Cam backlash is a condition (which is a knocking or bucking sound) that occurs when there is not proper clearance between the top of the cam and the top of a valve. The clearance between the two has to be adjusted from time to time as it can change due to engine heat.

Things You'll Need

  • Socket set
  • Remote starter switch

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Allow at least an hour or two for the engine to cool if it has been running. Cam backlash adjustments have to be made when the engine is cold.

Open the engine compartment hatch.

Attach the positive lead of the remote starter switch to the positive battery cable and the other wire to the starter solenoid terminal marked with an "S." Use the socket set to attach the leads.

Use the socket set to slightly loose all of the valve adjusters.

Bump, or depress, the starter switch several times until the rocker arm pushrod on the cam moves all the way down and does not move on the next bump.

Place the feeler gauge between the rocker arm and the top of the valve and tighten the valve adjuster adjustment nut. The feeler gauge should slide in and out from between the two easily when the backlash is adjusted correctly.

Remove the remote starter switch from the battery and starter solenoid and then close the engine compartment hatch.


  • Caterpillar 3406E Engine Service Manual; Caterpillar
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