Original Porsche Part Genuine Porsche part 99660315154

Code: 99660315154

Genuine Porsche part

Original Porsche Part

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Alternator Belt Pulley. Porsche Boxster 987 / Cayman 987C / 997

99760315401/2

Product Information

Alternator Belt Pulley With Free Wheel Lock.
Restore smooth and reliable operation of the auxiliary drive system with this Valeo Alternator Belt Pulley with Free Wheel Lock. Valeo is a recognised Original Equipment supplier of automotive electrical and drive-system components, producing high-quality parts designed for accurate fit, dependable performance, and long service life.

Fits:

Porsche Boxster 987 2.7L 2005-08/08
Porsche Boxster 987 S 3.2/3.4L 2005-08/08
Porsche 997 MK1 Carrera 2 3.6L 2005-08
Porsche 997 MK1 Carrera 2S 3.8L 2005-08
Porsche 997 MK1 Carrera 4 3.6L 2005-08
Porsche 997 MK1 Carrera 4S 3.8L 2005-08
Porsche 997 MK1 TURBO 2007-09
Porsche 997 MK1 GT2 2007-09
Porsche Cayman 2.7L 987C 2006-08
Porsche Cayman S 3.4L 987C 2005-08

Cars With Option Codes:
I480 - 6-Speed Manual Transmission
I481 - 5th-Speed Manual Transmission

Diagram Ref No 21

The alternator pulley transfers drive from the auxiliary belt to the alternator while its integrated freewheel/overrunning mechanism allows controlled rotational movement between the alternator and engine. This helps isolate the alternator's rotating mass from rapid changes in engine speed, reducing belt vibration, tension fluctuations, and shock loads throughout the auxiliary drive system.

What This Product Does:

Transfers auxiliary belt drive to the alternator.
Allows the alternator to freewheel or overrun when required.
Helps absorb rapid changes in engine rotational speed.
Reduces vibration and oscillation within the auxiliary belt.
Helps stabilise belt tension during engine speed changes.
Reduces shock loading on the alternator and belt-drive components.
Helps protect the auxiliary belt, tensioner, and alternator bearings.
Provides an OE-quality fit for reliable replacement.

Symptoms Of Wear Or Failure:

Excessive auxiliary belt vibration.
Belt tensioner visibly bouncing or oscillating.
Squeaking, chirping, rattling, or knocking from the belt area.
Pulley failing to freewheel correctly.
Pulley seized in both directions.
Excessive pulley play or wobble.
Roughness when rotating the pulley.
Premature auxiliary belt wear.
Unusual noises when the engine is switched off.
Increased vibration at idle.
Alternator bearing or tensioner wear associated with excessive belt loads.

Why Replacement Matters:

The alternator freewheel pulley plays an important role in controlling vibration and rotational loads within the auxiliary drive system. Unlike a conventional fixed pulley, its overrunning mechanism allows the alternator rotor to continue rotating momentarily when engine speed drops rapidly. This prevents the alternator's rotational inertia from repeatedly pulling against the auxiliary belt.
If the freewheel mechanism seizes, wears, or develops excessive play, increased vibration and shock loads can be transmitted through the belt system. This may cause accelerated wear of the auxiliary belt, tensioner, idler pulleys, and alternator bearings. A severely worn pulley can also affect belt tracking and potentially contribute to belt failure.
Replacing a worn or faulty component with this Valeo Alternator Belt Pulley with Free Wheel Lock 99760315401/2 restores correct overrunning operation, reduces auxiliary belt vibration, and helps protect surrounding drive-system components. Manufactured to Valeo's high-quality standards, this pulley provides accurate fit, smooth operation, and dependable long-term performance for Porsche maintenance and repair.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99760315401

99760315400

99660315250

99660315156

99760315401

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Original Porsche Part Genuine Porsche part 99660315154