Engine Diagnostics – Valve Train Components

Problem: Wear to the finger follower roller shaft

Causes:

• The load zone of the roller shaft is heavily worn
• Final stage of wear: The needles in the roller shaft have become loose

Help:

• The hydraulic pivot element and its finger follower must be replaced

Problem: Wear of the outer ring of the cam roller

Causes:

• Heavy wear of the outer diameter of the cam roller including significantly deformed geometries of the cam roller

Help

• The hydraulic pivot element and its finger follower must be replaced. The position of the relevant camshaft must be checked.

Problem: Wear to the finger follower and pivot element

Causes:

• Critical degree of highly abrasive wear of the ball head resulting in distorted ball head geometries
• Critical degree of highly abrasive wear of the recess resulting in distorted recess geometries

Help:

• The hydraulic pivot element and its finger follower must be replaced

Problem: Wear to the valve contact face of the finger follower

Causes:

• Highly abrasive wear of the valve contact face
• Clearly visible edges at the outer contact face imply that wear depth is several tenths of a millimeter
• Continued operation involves the risk of lever fracture

Help:

• The hydraulic pivot element and its finger follower must be replaced. The valve stem must be checked.

Problem: Bucket tappets – Wear to the bucket crown (2)

Causes:

• Adhesive-abrasive wear causing complete failure

Help

• The bucket tappet must be replaced
• Additionally, thorough inspection of the camshaft position is required

Problem: Scoring on the bucket tappet housing and guiding bore

Causes:

• Engine oil contaminated by excessive residual dirt
• Result: Bucket tappet seized in the locating bore

Help:

• Clean (scavenge) the engine
• Pay attention to cleanliness when installing the new bucket tappet

Problem: Solenoid valve for camshaft phasing does not work

Causes:

• Dirt particles in the engine oil impair the function of the control valve piston, the piston is seized
• Intermittent contact at the control valve electrical connection.

Help:

• The solenoid valve needs to be replaced
• The electrical connection must be examined and repaired, if necessary

Problem: Rattling noise in the phasing unit area at engine start-up

Causes:

• Excessive locking play
• Oil sludge build-up or oil contamination

Help:

• The phasing unit needs to be replaced
• Limited or no function of the phasing unit
• Clean (scavenge) the engine and change oil
• Replace phasing unit

Problem: Improper functioning of the pivot element, espec. non-return valve of the pivot element

Causes:

• Contamination with foreign particles washed into the valve lash adjustment component by engine oil
• Result: Improper functioning of the non-return valve

Help:

• The hydraulic pivot element and its finger follower must be replaced
  Attention:The manufacturer’s warranty expires if the parts are disassembled at the garage during the warranty period. In order to ensure proper functioning of the high-precision adjustment mechanism of hydraulic pivot elements, parts which have been disassembled must not be re-installed as this is detrimental to the system’s overall operational reliability.

Problem: Bucket tappets – Wear to the bucket crown (1)

Causes:

• Heavily worn bucket
• Such a running surface profile implies a heavy abrasion of the bucket tappet crown

Help:

• Bucket tappet and camshaft must be replaced