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HomeTech Articles > 993 Technical Article:

Pelican Guest Technical Article
Permission to publish this article is provided generously by
Robin Sun at
Be sure to visit his site for loads of 993 info!

How to replace the distributor cap and the rotor on a 993
(9 pictures to download)

Just like the spark plug the distributor cap and rotor needs to be replaced on a regular basis.  You should replace it every other time you replace your spark plugs.  Since my 993 have accumulated 28,000 miles I feel now it is a good time to replace it.  Most newer cars now days have electronic ignition without distributors, the reason why Porsche still uses the mechanical distributor system for the 993 is unknown.  But Porsche changed to the newer distributor less system on the 996. 

If you have any doubts about replacing your distributor cap, take a look at this below picture of my distributor cap at 28,000 miles.  The picture clearly shows the oxidation and the arching damaged from the high voltage sparks.  Click on the picture to get a closer view.

First step in replacing the distributor cap is to remove all the ventilation ducts that is blocking your way.  First step is to remove the two 10 mm bolts that hold the upper duct in place.

Pull the the temperature sensor from the upper duct housing by squeezing the metal clip.  Remove the upper air ducts.

Loosen the 1st strap on the bottom duct

Loosen the 2nd strap screw

After removing the heater coil element and the white robber ventilation hose for the distributor belt the lower air duct can now be completely removed

The distributor is held on by two philips screw, the screw is on very tight so be careful not to stripped the screws.  I stripped the lower screw on the bottom distributor cap and had a hell of time removing it.  Actually I have to remove the muffler, the muffler mounting bracket, remove the engine shroud, remove the heat exchanger pipe mounting screw that goes into the ventilation pipes.  It was not fun.  Since I was planning to change out the spark plug next I had to take most of these parts off any ways. But you want to be careful on the lower screw on the bottom distributor, it is at a awkward angle to get to.

Here is a picture of the stripped screw:

After loosen the distributor screw you first remove the cap with the spark plug wire still on it and replace the rotor that is underneath it.  There is no trick to that just pull off the old one and push in the new one.  There is a notch on the distributor shaft so there is no possibility of putting in the rotor incorrectly.

Place your new distributor cap next to the old one and replace the spark plug wires one by one, I know there is very little room to work with there, but I did it like that.  This way you eliminate any possibility of hooking up the spark plug wire to the wrong post. 

Comments and Suggestions:
draino422 Comments: The pictures show the cap w/the black cover on. Is this cover removable & if so, it is to be put onto the new dist cap?
March 5, 2017
  Followup from the Pelican Staff: The black cover is not to be removed. new ones will come with it. - Nick at Pelican Parts  
Vq-1 Comments: Is there an electronic ignition kit available to replace the mechanical distributor system?
March 29, 2014
  Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799. They can help you find the right part.
- Nick at Pelican Parts
robin Comments: I have a 1997, 993 with 50K miles. It has been running well however last nite I went out to start it and it just cranked but didn't fire up. This morning I diconnected and re-connected the battery and it fired up, then 15 minutes later it just cranked but would not fire up. Re place distributor cap and rotor maybe ?
June 2, 2013
  Followup from the Pelican Staff: Before you replace anything. Try arming and disarming your alarm. I have seen some of the alarm systems create a similar problem. - Nick at Pelican Parts  
Muda Comments: This was a good writeup. 60k miles on 17 yo original caps. I first put some WD 40 on the distributor screws. It will leak down into the threads. Took the correct sized phillips bit from my impact driver and put in into an 8mm socket and extension. Taped it up with electrical tape to make sure it all came out in one piece. Lots of pressure on the top and a sharp turn and each on came off easily. The rest is straight forward.
September 13, 2012
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
david993 Comments: Same here, did the replacement at 61000 miles, made a big difference.
September 11, 2011
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
Danskeren Comments: Wauuu - just did on my 60.000 miles engine. Made a huge difference. Engine starts immidialty on the first sparks now. And it takes RMPs at least twice as fast as before. And when I hit 4000 RMPs it allmost explodes :0
Cheapest and fastest performance upgrade I have made so far
August 10, 2011
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts

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