MBE 4000 DDEC VI Troubleshooting – Section 4.3 Improper Valve Clearance, Worn or Damaged Camshaft Lobes and Rollers

Section 4.3
Improper Valve Clearance, Worn or Damaged Camshaft Lobes and Rollers

Intake and exhaust valve clearance are adjusted by means of an adjusting set screw and locknut located at the push rod end of the rocker arm. See Figure "Intake Valves" for intake valves. Exhaust valve is similar.‪

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 1. Rocker Arm‪

 3. Valve Spring Retainer‪

 2. Valve Bridge‪


Figure 1. Intake Valves

To determine if improper valve clearance is causing the cylinder to misfire, check if a worn or damaged cam lobe or followers is causing the misfire.‪

  1. Bar the engine over and inspect the camshaft and roller followers for wear or damage.
    1. If damage is found on the camshaft lobes or roller followers, replace damaged components as necessary.
    2. If no damage was found to camshaft or roller followers, continue with task. Verify the proper lash setting following the procedure in the “Valve Lash Checking and Adjustment” section of MBE 4000 Service Manual (6SE420), Chapter 13, “Engine Tune-up”.

Section 4.3.1
Verify Repairs

Perform the following steps to determine if valve clearance adjustment resolved the misfiring cylinder condition:‪



To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked.‪

  1. Start the engine.
  2. Run the engine at 1000 rpm.
  3. Listen for misfiring cylinder.
    1. If engine is not misfiring, shut down the engine. No further troubleshooting is required.
    2. If engine is misfiring, shut down the engine and check for faulty fuel nozzle; refer to "4.4 Faulty Fuel Injector or Unit Pump" .

EPA07 MBE 4000 DDEC VI Troubleshooting Guide - 6SE568
Generated on 10-13-2008

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