concor

Sorry about the broken English.

Yesterday my 928s started to shake a bit and lose power. I had a look at the engine at a parking place, but didn't see anything. Not knowing what it was I drove along for about 30 minutes to my destination and asked a mechanic to have a look at it. He noticed that the second distributor rotor was spinning freely and towed it of just in case. I get the car back tomorrow or the day after (without being fixed).

Thing is, I need it to be behind my house up my driveway and he will drop it before my house. Can I safely start the engine cold with 4 cylinders? It is about 0 degrees here too, so the oil will be quite sturdy. Maybe if I remove the distributor cap quite a bit away from the broken rotor?

SeanR

I am guessing that the rubber belt between the rotors has broken, is this correct?

concor

Not sure yet. I get the car back tomorrow or the day after and all I saw with the mechanic was the second rotor spinning. I have to take it apart when I get the car back to find out what is causing the rotor to spin freely. I read somewhere on the forum to check the screw on the rotor, on both rotors actually to make sure they are fit tightly. Of what I understood I would be very lucky if that rotor screw is broken because then I don't have to take the whole thing apart.

But it's all new to me. The hardest thing I did was to change the disc brakes and the AT fluid and filter. Oh taking off the rear bumper was fun too...

Nicole

There were rumors in the past that driving with four cylinders can cause the torque shaft to snap. I don't have any proof or anecdotal evidence, other than this rumor.

However, just driving it up your driveway should not be enough to do any damage by itself. Having already driven 30 miles like this was a lot worse, and it sounds like nothing broke.

SeanR

I agree with Nicole, you should be fine driving it that short distance, just don't let it run very long. Remember, you are getting unburnt fuel on the bank that is not firing.

Mrmerlin

If you have a copy of the WSM there is a picture of the twin distributor and it shows how to remove it from the engine and then take it apart to replace the toothed belt that drives the other rotor, .
The distributor is easy to take apart, your hardest part may be getting a new belt, order 2 of them for a spare.
First put the engine at TDC and make sure the rotor thats turning is also at its hash mark on its distributor housing after the cap is removed.
Also very important make sure not to cross the coil wires when putting the caps back on or the engine will not run

concor

Nicole / Sean, thanks for the assurance! I'll drive it up the driveway then.

Cool Mr Merlin, you are the man. Yeah I have a WSM and I am very happy to read that the 928 is somewhat easy to take apart. I read some DIY how-to's on the forum for the 964 and other porsches and they said it was actually very hard. So I was afraid Actually I still am.

Mr Merlin, could you explain a little bit how to take apart the 928 distributor just enough to change the belt? Because what I read here and there it did not sound very easy actually. Is the 928 distributor perhaps easier than the 964 distributor? Thanks!

Mrmerlin

just follow the WSM it has a detailed picture and instructions, it is easy to do.
This is done on the workbench so the distributor has to be removed from the car,
set engine at TDC and then remove the hold down bolt then work on the bench...

soontobered84

Sean, I thought that there were two cylinders on each bank of 4 that fired, not four on one side. Have I been under a basic misconception all this time?

James Bailey

Yes two cylinders on each bank would not be running. The "rumor" about driveshaft damage is a Porsche Technical bulletin. Note the 4 cylinder 944 BECAUSE of the pulses of running on 4 cylinders has a big rubber donut behind the engine to smooth out the pulses. The pulses cause the shaft to twist untwist which is believed by Porsche to be a bad thing.... If your car is fitted with cat convertors you were lucky that it did not catch on fire. So is it "safe" to drive on 4 cylinders ? NO ! Also with the Euro dual distributor if the none moving rotor happens to be close to one of the contacts for a plug wire you can have spark at the wrong time for that one cylinder and that can have bad results depending on the timing of the spark.

James Bailey

Sean your wrong about that too !

John Speake

I did this job on my S2 and I didn't need to remove the dizzys from the car. I don't know why the WSM specifies this step. Otherwise follow the steps shown. The most difficult part was removing the two "flange washer" which are #8 on the diagram on page 28-48.

Mrmerlin

I removed mine so i could clean it , and also not drop any of the small bits into the engine bay, it was easy to on the bench.
But you could work on the dizzy while its still connected to the engine

Vilhuer

There are no cat versions of twin dizzy engines. Not from factory anyway.

Nicole

^^While that may be true, many cars in Europe were retrofitted with cats. At least in countries where governments offered tax breaks in return.