new VR but...

[nostatic]

Put the new VR in tonight. Took more than 5 minutes, but got it in. I of course didn't measure voltages with the old unit, but this morning started it up and noticed the lights pulsing.

So after the new VR, I still notice the pulse. I checked that battery. After shutting down the engine, it was a little over 13V (and slowly dropping). I started it back up and it was swinging between about 14.4V up to 15.4 or so.

Now that's with the new VR. That seems high, and it should be constant, shouldn't it? This new unit says for '75-81 Marchal "55W". It is smaller in size than the original unit, but the connector is the same size and the mounting screw holes are too.

What next?

[Tim Walsh]

is that 55w or 550w?

[Doug Zielke]

Todd,
I think you should check the alternator brushes. I would also take a close look at the commutator.

[nostatic]

Originally posted by l33t9eek
is that 55w or 550w?

It says 55W. A stock '79 should have a 980 Watt alternator...I don't know how they "rate" VRs though.

From the PP catalog: Voltage Regulator, external (for Marchal 55W Alternator), 911/911 Turbo (1975-81)

[DonDavis]

Todd,

Have you checked your ground connections. They may LOOK good but there could be some corrosion. I know my car was older but that happened to me. They would flicker and appear dim. After I cleaned the grounds, they worked like new.

[RoninLB]

there may be a stock in-line VR noise suppressor on the engine comp elec panel.. they are known to cause problems and can be disconnected without creating any noise problems.. maybe eyeball the wireing before by-passing it.. or borrow another known good unit.. all 3 wires from the VR to Alt go thru the suppressor.

the DF wire goes from the VR to suppressor to Alt for the field current. if an internal short between DF & D+ happens the field will be continuous.. if the DF is open the Alt won't charge.
BUT you may not have a radio noise suppressor. mine did ...........Ron

[RoninLB]

this is one style of radio noise supperssor that sits under the VR

[Rot 911]

Todd you definitely have a problem. With the engine at about 1000 rpms you should be getting a voltage reading at the battery of around 14.3-14.5 volts. Anything over 15 is definitely overcharging the battery. The 13 volt and dropping reading when you turn the engine off is normal.

[nostatic]

That looks like my bay...except I have less relays. But I do have the small box directly below the VR, and the bigger box right beside the VR (I had to move that one to get the VR off). But would a bad noise suppressor cause the high voltage situation? I'll see if I can bypass it tonight.

[surflvr911sc]

You should be able to just unplug it.

[RoninLB]

Todd..
I'm only saying that the suppressor is a possibility..
The suppressor is "In Series" between the reg and alt. So maybe the female plug that goes into the suppressor can be plugged directly into the VR, thus by-passing the suppressor.

and if a short develops between the DF and D+ in the suppressor the field current will be constant and the alt will over charge..

I should have my old good suppressor around somewhere, or borrow one, or remove the problem waiting to happen, or remove the present problem, or borrow a known good VR...........Ron

[scottb]

Todd: If the alternator is the original one, chances are it's going belly-up.

[targa80]

The noise suppressor can be bypassed since the mating connectors are the same.