Electrical guru's PLEASE HELP!!

Norm Faustino · Norm Faustino's Garage

Okay, I will try to make this understandable...
I just got done changing the voltage reg on my buddy's 82 sc due to an overcharging condition and immediately after the job I checked t see if it was back down to normal limits from around 17 to 19 plus volts, It was now at 15.3 to 15.7 which seemed normal.

Now! I went to start the car after the test run and the starter would not engage so I trouble shot it down to what I thought was a bad solenoid. But just for ****s and giggles I tried to jump it with another vehicle and what do you know? It started which indicated the battery was not charged enough to engage but now the voltage was showing no indication of charging at all after revving it and letting it idle I saw no change from the 15.3 volts (now keep in mind this is still hooked up to the jumpstart battery) so now I disconnected the jumpstart car and the 911 ran for a while but the voltage slowly came down below 9.5 until the car just died. I dont know a whole lot about charging systems but it seems to me that the alternatormay have damaged the new VR. FWIW the alternator is a paris-rhone model. I hope someone can chime in and help me with this as I am totally confused.??

stormcrow · stormcrow's Garage

You have to be careful how you jumpstart other vehicles. The guy I work with has a Ford Diesel and as a favor to a friend, jumpstarted his vehicle thus runing both batteries on the Ford Diesel.

You may have fried your voltage regulator but the alternator may be ok. That means you have to take it out and have it checked out.

Steve

"A Porsche does more then just go fast in a straight line"

PeteT · 04-07-2003, 08:51 PM

Norm,
A few years ago I replaced my VR and the new one was bad out of the box. I couldn't believe it. I took the alternator with the 'new' VR down to the local Autozone and they tested it and sure enough nothing!! Exchanged the VR with another new one and all was well. Double check that you have all your connections correct and if not maybe you just got a bad part. BTW my car is an 83 SC.
Pete

Joeaksa · 04-07-2003, 09:19 PM

Norm,

15 volts is way too high for your car. Voltage this high will boil a battery dry in short order. It may have warped the plates in the battery already.

Remember that the car runs off of the battery and the alternator just keeps it topped up. Try putting a known good battery in the car, starting it up and taking voltage readings. Anything over 14.7 or so is too high, while anything less than 13 or so with a load (high beams and window defrost on) is too low.

Joe

targa80 · targa80's Garage

If the VR is an external unit mounted on the side of the engine compartment then you can just hook up the old VR to see if you still get the 17~18 volts overcharge. Atleast this tells you that the alternator will put out the charge and your new VR is more than likely not functional. Using a multimeter and some jumper wires you can test the circuit /wiring to isolate the fault. If it is an internal VR in the alternator all bets are off.

cstreit · cstreit's Garage

15+ Volts at Idle? Still too high. Which regulator do you have, the external, or internal? (Or both, some car's were updated and left the old external one on, I just went through this)

Voltage should be in the 13.8-14.1 range. If you ran for long with a bad regulator, the battery is probably shot...

Wil Ferch · 04-11-2003, 06:24 PM

After these checks are made and you still can't find anything..my money's on a bad battery that needs replacing too.
---Wil Ferch

Joeaksa · 04-11-2003, 07:20 PM

Norm,

What did you find??? Update us when you make some progress!

Joe

Norm Faustino · Norm Faustino's Garage

UPDATE! Wow what a dumb ass! I just took the alternator back out and discovered that I had pinched both of the VR wires between the alternator and its housing, causing them both to sever and lose connection. This caused the subsequent failure of the second VR by probably shorting it and maybe damaging it to permanent failure. After splicing the wires and re-installing the alternator with the new but spliced VR, I got the same overcharge readings of about 18-19 volts.
i can only assume that the alternator is bad so I will just replace the whole unit with a factory reman. Now I can understand why a lot of repair shops wont replace sub assemblies like VR's and starter solenloids.
I will post and update after installing the new starter.
Thanks for all the good advice guys!

Joeaksa · 04-13-2003, 08:14 PM

Norm,

Even overhauled units can be bad out of the box. Take the one out of your car to a shop and have them bench check it. If their readings confirm that its bad then I would get it overhauled (new brushes and bearings) and new VR and you will have a known good unit in your hands.

Buying a overhauled unit gives you a totally unknown unit. Overhauling with all the above should cost less than $100 (mine was less than $75) and be done in less than a day at any good shop.

Joe