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Cooling Belt Sensor Replacement
 
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Pelican Technical Article:

Cooling Belt Sensor Replacement

Time:

30 minutes30 mins

Tab:

$90 to $100

Talent:

**

Tools:

5mm Allen

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 sensor

Hot Tip:

Use an Allen socket with a quarter inch ratchet, not an Allen key

Performance Gain:

No squeak

Complementary Modification:

Check your belts

The 993 is the last of the great air cooled 911's. Making sure that the cooling fan in your 993 is always functioning correctly is of great importance. While the older Porsche's use a single belt to run both the fan and the alternator, as displacement increased and there became higher demands on the electronic systems Porsche designed an independent pulley system for the 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.

Continuous operation of the cooling fan is critical for the proper cooling of the engine, so much so that Porsche designed a sensor to warn if the belt breaks. If your belt breaks this sensor will trigger the main warning light as well as a light signaling that the cooling fan belt needs attention.

The senor is located on the lower left side of the engine just beside the distributor caps. A lot of people think that this is actually a tensioner due to its design but it functions as a sensor only and provides no tension to the belt. If you are installing a new cooling belt please see our article on cooling belt replacement for proper tensioning instructions.

The sensor can develop a squeak over time and it is simple to remove it and lubricate the sensor pulley, but be aware that all of these sensors eventual will seize up and if this happens it can destroy the cooling belt and either leave you stranded or if you ignore it ruin the motor. The sensors will also eventual freeze in place and not recognize if the cooling belt lets go. While the sensor is expensive I recommend replacing it if it is beginning to fail; it is cheaper than a tow and if it ruins the cooling belt having to remove all three belts at the side of the road to replace it can be a pain.

The sensor is located on the lower left side of the motor, right on the shroud.
Figure 1

The sensor is located on the lower left side of the motor, right on the shroud. The pulley (red arrow) can fail in many ways; it can seize up, the plastic can break up and the arm can get stuck in position and not let you know when the belt breaks. If it is starting to go bad you might hear a high pitched squeal. You should also check the belt for a sheen or degradation, this is a sign the sensor is not functioning correctly.

Begin removal by disconnecting the electrical connection.
Figure 2

Begin removal by disconnecting the electrical connection. Squeeze in on the metal tap (red arrow) and pull the connection straight off.

You will want to use a 5mm socket with a quarter inch drive to remove and install the sensor.
Figure 3

You will want to use a 5mm socket with a quarter inch drive to remove and install the sensor. It is a tight fit and you may strip things using an Allen key. The single bolt that holds the sensor in place is one that you definitely do NOT want to strip.

Loosen the bolt and then remove the sensor.
Figure 4

Loosen the bolt and then remove the sensor. You can see in this photo that the Allen will be very difficult to get out if you strip it. Also people recommend lubricating the pulley bearing (yellow arrow), I do NOT, just replace the sensor, it is too important to have not working correctly or fail while you are driving your 993. Installation is the reverse of removal.

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