Alternator problem – 964?
 

I have experienced some problem when driving , sometimes the car does not run properly. It feels like it is not getting enough gas, it hesitated during acceleration. This is not a constant problem, it has happened 4-5 times over the last months. I have read that the DME relay is sensitive to variations in the voltage, so I think this could be alternator problem? I have put in a new battery and that seams OK.

I have hooked up a digital multi meter to the battery so I can check the voltage when driving. I have only had a couple short trips so far, but the voltage is constant at 13.4 – 13.6 volt when driving (1000 – 3000 rpm). A couple hours after I have parked the car it shows 12.6 volt.

Is 13.4 – 13.6 low when driving (with normal load lights, fan, radio) for 964?
Any other ideas what the problem could be?

altenator
 

I had the same problem

1) the alternator was bad (low voltage)

2)check the belt on the dual distributor I thinks this should be your problem


Andrew

At idle, your voltage should be 13.8-14.4 volts. Adrian Streather suggests increasing RPM until engine reaches 13.8 volts. If RPM is above 1200, he says you have a problem with your alternator / regulator.

I think that's optimistic.

12.5 at rest
13.0-13.5 at idle
13.5-14.0 at 2500 rpms.

Mine has been like that for years since my SC conversion. I run a Yellow top Optima. Converted to a single belt.

YMMV

I have now changed the voltage regulator and it looks OK, I hope it stays like that :)

I now have:

13.7 at idle
13.9 at 2500 rpm
14.0 at 4000 rpm