Why Vent and Why Inspect?

A design fault  on engines up to August 1993 that you MUST fix if not already done so is to add ventilation to the distributor to prevent ozone perishing the distributor drive belt.  If this breaks you will be running on one plug per cylinder and serious engine damage can occur.   Please check out Adrian Streather's summary of the problem.
For more details and a picture of a corroded  belt visit Marv De Beque's 964 - The Good, The Bad and the Ugly .

Jeff Curtis, Eastern Vice President/Track Chairman of First Settlers Region - PCA, supplied me with this photo of the damage caused to two cylinders after the owner continued driving with a broken belt and even took the car on a couple of track days.

Click here for the full story and a bigger photo.
 

Fitting a Ventilation Kit

My belt went at 49,000 miles.  I spotted something was wrong due to poor performance and uneven running.  My specialist replaced the belt but neglected to fit a Ventilation Kit at the same time.  Porsche Technical Bulletin 9403 gives instructions on how to do this as I do below.

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

Firstly prise of the oval plate arrowed on the distributor with a screwdriver.

Then remove the large black air guide pipe as we need to drill a hole in it at the green dot.  The pipe removes by loosening jubilee clips at top and bottom.  You will also need to remove two sensor connectors on the pipe.  I also removed the two sensors near the distributor so that I had easy access to the plate.

Drill at 18mm hole in the pipe, 40mm to the right of the tail light ventilation nipple.  Deburr the hole and remove all shavings.  Install the rubber grommet (B) into the hole and install the white connector (C) into the grommet.

Install the distributor connector (A) into the hole in the distributor where the plate was.

Finally refit the air pipe and connect back up all the sensors.

Install the hose (D) onto the new distributor and air pipe nipples and route as shown here.

Done.

Elliot Davies' Lazy Mechanic's Tip

Refitting the air pipe is quite a hassle, especially getting the bottom jubilee clips on.  Elliott avoided drilling a hole in the pipe by connecting the vent hose into the rear light cluster vent hose using a T-Piece.  These are the same T's used to join screen wash hoses.  Click the photo for a blow-up view.  Looks good to me!
 

Distributor Belt Inspection

If you would like to take a peek at your belt to check its status, the following instructions were posted by jrichard82@home.com on our SmartGroup

Jack, I just did this after hearing horror stories about busted belts, I wanted a look. If you are concerned that the belt is broken you can pull the primary distributor coil wire, if the car still runs the belt is intact.

The access to the lower screw on the secondary cap cannot be reached by a standard screwdriver, they are too long and a short 3" driver is too short. The combination I used was a 1/4" drive ratchet wrench with a 1" extension, and a Philips socket. This puts it right at the length to reach the screw:

1. Remove the blower duct bands and sensor wires, move it out of the way.
2. Put a rag in that big socket and screw eatin' hole. (or you may develop a severe rattle when you drop your wrench in there.)
3. Remove the primary distributor cap swing out of the way. I could do this with the wires attached, but the rotor had to be removed.
4. Use the above wrench combo. Once you get the Philips socket in the screw at an angle straighten the wrench, and it will slide between the cap and the heat exchanger outlet. (don't pry on the cap.)
5. Push down on the wrench HARD while turning. If you can, tap on the top to break it loose before turning.
6. Once the cap, rotor and shield are off the belt is visible under the advance mechanism. You can rotate the engine by hand or with the starter and inspect the length of the belt. (If you use the starter look out for the loose caps or you'll get a surprise...)
7. Install is the reverse of above.

Good luck! may your belt be supple and smooth!

Distributor Caps and Rotor Arm Replacement and Belt inspection

Elliott Davies took a look at his distributor caps and didn't like what he saw re. the contact condition.  Check out his guide to changing caps and rotor arms.  Also see photos of how to inspect the distributor belt.

Distributor Belt Replacement

If your belt goes or you want to take a look at a perished belt, visit Louis Guerra's Site for detailed instructions on how to replace.  Fairly complex job.  I would recommend getting specialist to fit.

Distributor Removal

However, you may want to remove your distributor and send it off for refurbishment or for a new belt installation.  Here are instructions from ?

You do not need to remove the plug wires from the caps, just unclip them and move them out of your way.

1. I would rotate the engine clockwise until the Z1 mark on the crank pulley lines up with the little mark at the bottom of the fan housing. You can confirm TDC at this point by ensuring that the main distributor rotor is pointing toward the #1 cylinder's upper plug. After you have done this, note the direction that the rotor is pointing and mark this with a grease pencil or Sharpie. When you reinstall the distributor, you want to make sure that the main rotor is pointing at the same place.
2. Remove the nut and washer that secures the distributor in place. There is no adjustment for timing since is done in software and the above steps ensures reference position.
3. Voila', remove the distributor with a lifting and slight rotating motion. It might take a little tug to get it loose. The rotating motion allows the helical cut gear to clear the crank gear that drives it.
4. Cover the hole with a very clean rag that has no foreign material stuck to it.

Done!