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Pelican Technical Article:

Alternator Belt Replacement

Time:

30 minutes30 mins

Tab:

$5 to $20

Talent:

**

Tools:

24mm wrench, M10 12 point

Applicable Models:

Porsche 993 Carrera (1995-98)
Porsche 993 Carrera 4 (1995-98)
Porsche 993 Carrera 4S (1996-98)
Porsche 993 Carrera S (1998)
Porsche 993 Targa (1996-98)
Porsche 993 Turbo (1996-97)

Parts Required:

Belt

Hot Tip:

Make note of the washer placement

Performance Gain:

Functioning Alternator

Complementary Modification:

Change the other belts

The 993 is the last of the great air cooled 911's. While the older Porsche's use a single belt to run both the cooling fan and the alternator, as displacement increased and there became higher demands on the electronic systems, Porsche designed an independent pulley system for the 993 alternator and cooling fan. The alternator fan pulley is smaller meaning it will spin faster at idle to provide for the demands of the electrical system while the cooling fan pulley is designed to place the correct volume of air over the motor for the entire RPM range. Porsche later redesigned the pulley for the alternator increasing the size and weight of them; if your 993 does not have the upgraded pulleys you should consider upgrading the next time you change your belt,

There are three belts on the 993 engine that drive the A/C compressor, the alternator and the cooling fan. The A/C compressor belt is the outer most belt and needs to be removed to replace the other belts. These belts, like any belt, will wear out over time. You should inspect all of your belts every six months for signs of drying out, glazing, cracking or separation and replace them at the first signs of deterioration.

Over the years your car may have been serviced by multiple people including previous owners and this can lead to parts replaced with different size fasteners and hardware. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches. If something is different on your vehicle please let us know and share your info to help other users. If you have any questions or comments or even a different procedure you would like to share please leave it below and please leave your vehicle information.

There are three belts on the 993 engine that drive the A/C compressor (blue arrow), the alternator (red arrow) and the cooling fan (yellow arrow).
Figure 1

There are three belts on the 993 engine that drive the A/C compressor (blue arrow), the alternator (red arrow) and the cooling fan (yellow arrow). Whether you use your A/C system or not you will need to know how to replace the belt because it needs to come off to replace either of the other two belts.

You will need to remove the A/C belt to replace the alternator belt so please see our article on A/C belt replacement for additional assistance.
Figure 2

You will need to remove the A/C belt to replace the alternator belt so please see our article on A/C belt replacement for additional assistance.

The alternator pulley is actually made of two separate parts.
Figure 3

The alternator pulley is actually made of two separate parts. It is held in place by a 24mm nut (yellow arrow) but you will need to use a M10 12 point to hold the alternator shaft from turning (red arrow) while loosening the nut with the 24mm wrench.

Remove the nut and the spacer behind it, there may also be some flat shims behind this spacer.
Figure 4

Remove the nut and the spacer behind it, there may also be some flat shims behind this spacer. These spacers are used between the two pulley halves to adjust tension on the belt. Note how many shims are on the outside of the pulley and how many between the halves.

Remove the outer pulley half.
Figure 5

Remove the outer pulley half.

Count and remove the shims (red arrow) between the pulleys.
Figure 6

Count and remove the shims (red arrow) between the pulleys. There should be four shims total

You can now remove the belt from the crank pulley.
Figure 7

You can now remove the belt from the crank pulley.

Porsche redesigned and upgraded the pulley to a larger diameter and thicker weight; if you still have the stock pulleys on your vehicle you really should consider purchasing the upgrade.
Figure 8

Porsche redesigned and upgraded the pulley to a larger diameter and thicker weight; if you still have the stock pulleys on your vehicle you really should consider purchasing the upgrade. The old pulleys are 72mm in diameter and the new one are 76mm. Installation is the reverse of removal. Begin by placing the shims in the same amount and places they were when you remove the belt, tighten everything up and run the engine for a few minutes. Check the tension and there should be 5mm deflection and the midway point using finger pressure. If you need to adjust the tension add or subtract shims from between the pulleys. Adjust, run the engine and recheck as needed.

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