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    2004 Mercedes Benz Truck ML350 4WD 3.7L SFI SOHC 6cyl

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    Cam Shaft

    Inspect/Test/Service/Replace

    The camshaft is driven by the crankshaft by one of three methods:

    • Gear drive
    • Sprockets and timing chain
    • Sprockets and timing belt
    Camshaft parts. Courtesy of Ford Motor Corporation.
    • Check the camshaft for:
      • A plugged oil feed,
      • The correct cam lift or
      • Any broken or severely worn areas.
    • Check each lobe and journal for:
      • Scoring,
      • Scuffing,
      • Fractured surface,
      • Pitting,
      • And signs of abnormal wear.
    Steel camshaft and roller followers in good condition.
    Badly burned and worn camshaft bearing bores.

    Normal lobe wear is a pattern slightly off center with a wider wear pattern at the nose than at the heel. The off-center wear is a result of the slight taper of the lobe used in conjunction with the convex shape of the lifter to rotate the lifter.

    Normal wear patterns are slightly off center on the lobe. Reprinted with the permission of Ford Motor Company.
    • If the wear pattern extends to the edges of the lobe, the lifter will not rotate.
    • If there is any scoring or galling, the camshaft will have to be replaced or reconditioned.

    Premature lobe and lifter wear is generally caused by metal-to-metal contact between the cam lobe and lifter bottom due to inadequate lubrication. The nose will be worn from the cam lobes, and the lifter bottoms will be worn to a concave shape or may be worn completely away.

    This type of failure usually begins within the first few minutes of operation. It is the result of insufficient lubrication.

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