How do you change a distributor cap on a Porsche 944 1984 non turbo?

Answer 1

Changing the cap is easy but the problems you can cause are not. Make sure you are careful and do everything step by step. DO NOT Take off the wires until the proper step. Read all the instructions first so you can see the stupid things NOT TO DO!!

1. The experts say take the ground strap off the battery. That prevents the engine from getting power. If a gremlin cranked the engine while you were working in this area things could get unpleasant.

2. Make sure you have all the parts necessary. I recommend a rotor button and distributor cap as the minimum. But if your distributor cap is really shot then a set of spark plug wires will probably be a good buy too.

3. Using a flat bladed screwdriver that fits in the slot, you push in the metal studs on the top and bottom of the distributor cap and turn a 1/4 turn. They are not screws. Try to take the cap off. If it doesn't come off then push in the stud and turn another 1/4 turn. Try to take it off. If it doesn't come off, repeat and I recommend doing one side at a time to make sure that side is loose. They look like screws but they are pieces of L-shaped metal rods that fit in a slot and are turned a 1/4 turn. The spring tension against the underside of the housing is what holds the cap on.

4. With the cap off, set the new cap beside it oriented the same way. Take one wire off at a time and put it in the corresponding hole in the new cap. Pull on the big rubber boot and not the wires. They stick and may have to be pried loose with a small flat screwdriver. Be careful here as if you split the boot the wire must be replaced. If you pull on the wire and not the boot, you usually break the wire. Each wire MUST go in the proper hole or the car either won't start or the worst case, the engine can self-destruct.

5. If you decide to replace the sparkplug wires too (my recommendation) then you do this. With the new cap sitting beside the old one (still in the car), you take the longest new wire. Pull the wire off the spark plug closest to the passenger compartment. Put the new wire on the spark plug. then as you pull the old wire off the looms (the u-shapped plastic pieces holding the wires in place) you put the new wire in its place. Finally you get to the distributor cap, put the new wire in the new cap in the coresponding hole as the old one was in. Be careful and note how the boot on the old wire is oriented to the cap and put the new one on the new cap oriented in that same way. You want to route the wires in the same places in the looms because electromagnetic induction can cause "cross-firing" which can also destroy the engine.

6. The rotor button is held on by a set screw on the side of the button that faces the ground ( so you can't see it). I don't remember what size Allen wrench you use and unfortunately some cars use metric screws and some cars use standard but I would try metric first and yoour new button should have a new screw so you can try the size that fits that one first.

This is an easy job if you do it step by step and have all the necessary parts. If you get in a hurry or try to take a shortcut then you can cause yourself a lot of problems. The above description is how I did it. I jerked all the wires off first then didn't know which went where. I finally found the firing order to see what hole which wire went in, but that reference ( Porsche website) mentioned the cross-firing problem if the looms are not done right. Naturally, it didn't have a description of how to do it right. Luckily someom at work had a 944 and after waylaying him at his car, he agreed to come over and let me look at hhis as I fixed mine. It isn't a problem any longer as I own four of the things now. A 1983, 1984, 1985 early model and 1985 late model. I am a soldier stationed in Germany and the things are easy to buy from PCSing soldiers here.