Distributor Questions

[smpiers]

Hello
This weekend I took my distributor apart and I have a couple questions.
1. The contact surface look clean, however, is there a wear spec I can/should check?

2. How does one determine if trigger points need replacing?

Anything else I should do, test, look at while distributor is apart?

Thanks,
Shane

[John Rogers]

You can clean the trigger points with contact cleaner after using a points file if they look pitted, but replacement is best. I used to replace ours when the car started to run a little poorly and after checking checking everything. Now I replace them when doing plugs, etc. Good luck

[Roland Kunz]

Hello

EFI trigger contacts doesn´t need to be replaced. Clean them like any other electronic contacts; towel and isoprohylalcohol. They are very delicat so be carefull.

To check them just use a Ohmmeter and turn the distributor shaft.

They live far over 100000 mls.

Grüsse

[pbanders]

Roland (as usual) is right. The FI trigger points last over 100K miles. They only conduct a very small current, as they provide ground to the base of two transistors in the ECU that are part of a flip-flop circuit.

The only maintenance that they need is a small dab of Bosch distributor grease on the cam lobes. Later models of the trigger points have a small guard that prevents any of this grease from getting on the contact points.

It's easy to statically test the points (turn the shaft and see if you get an alternating ground), but proper testing requires specialized equipment (breakout box and an oscilloscope). If you suspect the trigger points are faulty (e.g. dead injector bank (1-3 or 2-4), erratic injection, etc.), the best way to test the points is to switch them out with new points.

As for what else you should do while you have your dizzy apart, here are a few:

1. Remove the contact plate and check it for smooth operation. I clean the plate and relubricate it with a bit of light grease or motor oil.
2. Check the condition of the copper strap between the two pieces of the contact plate. If the strap is broken, the plate is no good and will have to be replaced - you can try soldering or brazing the strap, but I've heard this is not easily done.
3. Check the operation of the vacuum advance/retard device (if you have one). Use a hand vaccum pump and make sure that it moves smoothly and that it doesn't leak.
4. Inspect the mechanical advance device for any broken springs, dirt and debris, etc. Clean it carefully and relubricate with light grease or motor oil
5. Check the distributor shaft for any obvious side-to-side play. If excessive play is present, the distributor will need to be rebushed. John Larson on Rennlist can provice this service.
6. Remove the felt disc that is on the top of the distributor shaft and make sure the "C" ring clip is locked into place.
7. Always change the external O-ring on the base of the dizzy when the it's removed from the car. This the source of many an oil leak.

Brad Anders

[This message has been edited by pbanders (edited 06-19-2001).]

[smpiers]

Where does one get the replacement felt washers for the distributor? As well as the rubber orings?

Thanks
Shane

[Dave at Pelican Parts]

Well, you could try your favorite on-line Porsche parts store. (hint, hint, hint...)

Remember, just because it isn't in the on-line catalog doesn't mean we don't carry it!

--DD

[little greencar]

I've read :
the points are good for 50,000 mi.
Its not the contacts that go but the springs loose their temper and bounce.
There is a rental test box available a Pelican. (Have not been able to confirm).

I hope:
I can pick up a cheap/slow osciliscope and take a look at these contacts in action to ditirmine if they need changing out, at $200/ I need to be sure because there is a million other things need buying; ofcourse.

I'll get back if I get anythingelse. thanks