This is my first post but I have been reading reenlist .com for a couple months now,
Even before I got my car,
I have a 1980 928 euro, the car seat In a barn for 5 years according to the previous. Owner. Needless to say,I remove the tank.and clean it
Clean the fuel lines,put new inyectors,distributor caps ,wires, timing belt,water pump, fuel pump, clean all the grounds ,oil and coolant.
Crank the car after priming the oil and fuel of course,and run pretty good,after warm up the idle went a little low, so I adjust the idle speed and make a small adjustment in the air fuel ,after that I adjust timing, and run very nice and even, I smile and shut it down.
Now the bad news and the reazon I need help , I notice the alternator red light was on and after checking the battery voltage I only have 11.6 v so was not charging. I took the alternator off clean the contacts,and installed back up but look like is shorting out it actually smoke? I took it back out and connected while is off the car and is fine, but if I ground it it will spark and smoke.
Also when I connect it off the car with the alternator in the ground I put the two red wires together and the head lights on the car turn on?.
I went and try to start the car and the wipers come on and the car don't start no more.
What have I done to my car ? I know call me idiot for try to start it with out an alternator, I was just try to see if I burn something up.
So now what shoul I do I am afraid. I have order the wiring diagrams, but don't really know where to start.
Thanks in advance. Please help!!! My smile turn in to tears.

 

Starting without an alternator is not likely to do any harm on its own, however the connections being made at the alternator can be important for some years (so they need to be at least bolted together).

So:

Charge the battery well, if the alternator has failed the battery will be at low charge. Seems you have an alternator problem (likely fried rectifier diodes) - so get the alternator tested & rebuilt (or replaced) first then get everything back together properly and try again. What you describe with the lights etc is very odd - but may just be symptoms of low voltage anomalies with the relays. Don't panic yet - just be systematic.

Alan

 

May I suggest you replace the fuel lines if they are original. Cleaning does not rejuvenate 35 year old rubber.

Read the New Visitor thread at top here.

Search "fuel lines" and "engine fire"

Welcome and good luck.

 

Thanks Alan make me feel better .
While looking at alternator replacement I notice 928 specialist site mention an alternator charging resistor
Where that go if I need it.
Any recommendations in an alternator 90 ams 200 ams.

 

Get the stock alternator. The charge resistor is built into the instrument pod. Don't worry about that yet.

Alan

 

The alternator in the car is a valeo made in France I am assume is the stock I also going to order the gasket and the cooling cowl. And the hose
Steve: I did replace the rubber fuel lines when I clean the tank I have to replace two more by the engine.
Thanks for the sugestion this I'd a valuable information

 

I got the alternator and the wiring diagrams also
I could be wrong in this. ( im a machinist )
With the battery fully charge I getting power in the headlights and this is not right I don't have the headlight switch on and according to the diagram if I undestand right fuse 26 should not have power until the switch is on
So that tell me the relay isn't working
Am I right?

 

I see is so many treads about headlight problems, I guess there is no answer to my question
I took my relay a part and is in fact a wire loose in there is so small I don't know how I am going to solder it back again,
My relay part number is 928 618 107 00
And I can only find a 928 618 107 07. Does anybody know if this is just a new part number?

 

Fernando - you need 928 618 107 05 and my price is $87

 

Cool thanks I will call you roger.
I get one for spare in the mean time I was able to solder the wire inside the relay. And look like is working fine now.
I install the new alternator and it is charging. ( after I bump the gas pedal)
But the red light still on
I am getting 14.35 v at the battery
Why is the light still on?

 

14.35v at the battery is a bit high - but the alternator is working. See what the voltage is when the car is fully warmed up?

For the charge light to still be on it is likely to be a connection problem. The wire to the small (61 or D+) terminal on the alternator may be connected incorrectly or is shorted to ground somewhere.

Check the small wire is connected to the D+ terminal on the alternator - not the grounded case.

Check the voltage on the blue wire on the 14 pin engine connector (near jump post) - this connects to the alternator small terminal - it should be 0v with ignition off. 1-2v with ignition on (not running) and ~battery voltage when running.

Alan

 

Thank Alan for the help
The alternator blue wire is connected to D+
The wiring diagram for a 1980 only show the blue wire
And the big red power wires
This is how the alternator was originally wired
I will check the voltage in the morning
Again as you ask me.

 

The voltage at the battery post after fully warm is still 14.30 V
11.98V before hit the gas. (Cold)
And 14.40 V at the blue wire also fully warm
.220 V on blue wire at 14 pin ignition on car off

 

Do you mean it is 11.98v at idle and 14.3v at say 3K RPM?

11.98v at idle means it isn't generating then. 14.3v all the time is too high and will likely damage your battery.

If the blue wire is at 14.4v then the charge light should be off - what is the blue wire doing when at idle? when is the charge light on - just at idle?

It seem you may still have an alternator with a regulator issue or the exciter wire has other connection problems.

Exciter wire voltage with car full off =?v
Exciter wire with ignition on car not running =?v charge light on/off?
Exciter wire car running at idle =?v charge light on/off?
Exciter wire car running at 3kRPM =?v charge light on/off?

Alan

 

No I mean is 11.98 when I start the car but when I rev the engine it jump to 14.3
The light is on all the time. Ignition on, or engine idle,or at 3000 rpm.
Blue wire at the 14 pin is 14.4 at idle