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The distributor drive belt - the one you do NOT want to dry out and break.

Fitting your with a Distributor Ventilation Kit.

adapted from an original article by John Miles of

Why is it necessary to Ventilate the distributor?

A design deficiency on 964 engines up to August 1993 that you MUST address as soon as possible (if you haven't already done so), is to install a distributor ventilation kit to prevent ozone perishing the distributor drive belt. If this occurs and the distributor belt fails your second distributor would stop turning and the spark from the rotor would continuously discharge on one spot. This continuously arcing spark is an engineering phenomenon known as “welding”. It is possible that the cylinder head could start to melt locally and the local hotspot, metal relocation and localized thermal expansion could very likely cause the engine to seize.

Fitting a Distributor Ventilation Kit

One of the first symptoms of the distributor belt degrading that an observant owner will detect is reduced overall performance and uneven running. Porsche Technical Bulletin 9403 gives instructions on how to accomplish the installation of a distributor ventilation kit which are very similar to the instructions below.

The Ventilation Kit is part number 000 043 202 52 and contains

[A] Black Plastic Distributor connector.
[B] Black Rubber Grommet.
[C] White plastic connector.
[D] Clear flexible Hose.


Figure 1. “Before” Picture.


Step 1) Remove the large black plastic air pipe, as it is necessary to drill a hole in it in the approximate position indicated by the green dot (see picture on left). The pipe is removed by loosening its retaining jubilee clips at top and bottom ends.

Step 2) Detach the two sensor electrical connectors located on the large black air pipe in order to remove it from the car.


Step 3) In order to obtain easier access to the metallic distributor body where it is necessary to remove a blanking plate, it is also necessary to remove the two sensors near the distributor.

Step 4) With the large black plastic air pipe removed from the car, drill an 3/4 inch (18mm) hole in it approximately 1 and a 1/2 inches (40mm) to the right of the existing ventilation connector which has a tube leading to the LH tail light. Deburr the newly drilled 3/4 inch (18mm) hole, remove all shavings and then install the black rubber grommet into the hole as shown.

Figure 2. The black grommet [B] inserted into
the 3/4 inch (18mm) hole.




Figure 3. White plastic connector [C] inserted
into grommet [B].



Step 5) Insert the white plastic connector into the grommet that was previously installed in the hole in step 4.

Step 6) Reinstall the large black plastic air pipe, securing it with its two jubilee clips and be sure to reconnect all the sensors.


Step 7) Prize off the oval blanking plate located as shown on the distributor body with a screwdriver
(as indicated by arrow in Figure 1).

Figure 4. Distributor blanking plate removed.




Figure 5. Black plastic connector [A]
installed on distributor body.


Step 8) Install black plastic distributor connector [A] into the hole in the distributor body that the blanking plate was removed from in Step 7.


Step 9) Connect one end of the clear flexible hose [D] to the newly installed distributor hose connector and the other end to the white plastic connector [C] mounted on the large plastic air pipe.

Step 10) Check all hoses and clamps that were worked on are tight and secure, then have an innocent bystander start the engine while you watch to ensure all is well (before they start the engine ensure that the bystander knows to shut it off immediately if you become loud and agitated).

Step 11) Close engine deck lid, locate your favorite beer and consume it contentedly while showing bystander what a great job you did.

Figure 6. “After” picture - Completed Distributor Ventilation Tube kit installation.



Many thanks to John Miles for his permission to use an adaptation of his original article. For more excellent data on 964's and a great website go to


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