Georgia Fiero Club Forum

All Things Fiero => Tech Tips, Tech Questions => Topic started by: Donster on November 06, 2011, 04:41:25 pm

Title: Do I need a new alternator?
Post by: Donster on November 06, 2011, 04:41:25 pm: Symptom on the 85 V6
When I start her up, I'm only getting between 8 and 9 Volts. It takes about 3 to 5 minutes to get 13 to 14 Volts.
During this time I can't hit the brakes or even use my turn signals, all the car's lights dim, RPMs drop and she's about to die.

Sound like an alternator going bad?

If yes, anyone have a good one for sale?

\D
Title: Re: Do I need a new alternator?
Post by: TopNotch on November 06, 2011, 05:06:44 pm: What happens if you give it a little gas right after starting up. On my 86 SE, the voltage reads low after startup until I do that. Then it's up, even at idle.
Title: Re: Do I need a new alternator?
Post by: Donster on November 06, 2011, 05:11:12 pm: Nope, no change - constant 8 Volts, even after revving the engine or staying on the gas. Won't go up to 13/14 Volts until she's got temperature
Weird, isn't it?

\D
Title: Re: Do I need a new alternator?
Post by: Fierofool on November 06, 2011, 06:01:42 pm: The 87 started doing that. At first, you had to rev it like Pat suggested, then it got to where it was going down the road before it would get to the straight up point. It gradually got worse and worse until it was only showing about 8-10 volts when I replaced it.
Title: Re: Do I need a new alternator?
Post by: Donster on November 07, 2011, 08:23:56 pm: After doing some research regarding the symptoms I've been experiencing, I read multiple times to check for bad ground; here's one thing I found:

So here are some huge ground cables I installed tonight. Talk about serious gauge/diameter. The lighter is for comparison. ;D

These are the ground cables from a big UPS system at a data center. I installed a short one from the engine to the battery tray and a long one from the trunk hinge to the top of the plenum: I have to say, my lights shine much brighter now, but hitting the brakes or turning on the A/C still seems to draw a bit too much so I think I should just go ahead and put in a new alternator. It certainly didn't hurt to replace my old worn ground straps.

BTW: Constant 14 Volts as soon as I crank the engine. But like I said, as soon as there is an electrical draw, voltage drops and the belt starts squealing.

\D
Title: Re: Do I need a new alternator?
Post by: TopNotch on November 07, 2011, 09:32:08 pm: Quote from: The Don on November 07, 2011, 08:23:56 pm

BTW: Constant 14 Volts as soon as I crank the engine. But like I said, as soon as there is an electrical draw, voltage drops and the belt starts squealing.

\D

Dodgerunner's belt tensioner (http://home.windstream.net/dodgerunner/Fiero1_files/BracketInfo.html) will fix the belt squeal for good.
Title: Re: Do I need a new alternator?
Post by: Fierofool on November 07, 2011, 09:36:35 pm: Don, regarding grounding to the plenum bolt, I read an article, I think by The Ogre or DarthFiero about the grounding qualities of the plenum bolts. There is an upper, intermediate and lower plenum. Each is insulated from the engine by a set of gaskets. The only thing giving continuity are the chrome plated bolts, which are clamped against a painted upper plenum. The ground path is very circuitous through the bolts and if they have any kind of thread sealant on them, it reduces metal to metal contact. If you could find that bolt where the braided ground strap anchored you would be much better. There's also a sensor that Robbie anchored to one of the bolts up there. It needs to be relocated to a better ground.

I have a DodgeRunner idler pulley for a V6 if you want it. You'd have to change to a larger belt. It isn't a tensioner, but it helps to reduce belt squeal by giving better wrap around contact on the other pulleys.
Title: Re: Do I need a new alternator?
Post by: Donster on November 07, 2011, 10:17:59 pm: Like I said, only squeals when there is too much draw on the alternator. A new alternator might fix it.

I connected the new ground to the bolt that also has the throttle bracket on it and tested it first with a multi-meter. Ground connection was fine on that one.

Charlie, which sensor are you talking about?

\D
Title: Re: Do I need a new alternator?
Post by: Fierofool on November 08, 2011, 08:28:04 am: At the right front of the lower plenum was a black wire that had been cut and spliced. It had a split connector on the end that was inserted underneath the right front plenum bolt. I moved it to attach to the MAP sensor mount. I think it had a green butt splice connector on the wire.
Title: Re: Do I need a new alternator?
Post by: Donster on November 11, 2011, 06:18:37 am: Found it and ground it! ;D

\D
Title: Re: Do I need a new alternator?
Post by: redraif on November 17, 2011, 12:30:55 pm: so how is the car now? Did you swap alternators?

I had an overcharge condition an intermittent start and battery drain. The orge suspected my sense line was damage or corroded and the alternator was getting a false feedback as to the current usage so it kicked the alternator into overdrive & started frying things. I replaced the whole sense line and charge line. I also stepped up to an 8 gauge charge line. My battery cables are 2 gauge. I took all grounds off one by one and used switchboard pads to scuff off any grime or corrosion. I did this on the bolt, the mounting point and the wire ring end.

in the end all was fixed by my work. Which did the trick I don't know. But I would say go over all you alternators lines. If you have stock battery cables then swap to new ones. Corrosion can occur inside and you will, never see it.
Title: Re: Do I need a new alternator?
Post by: Donster on November 17, 2011, 12:57:24 pm: Well, like I mentioned at the meeting, all symptoms are pretty much gone, besides the occasional squeal.
Even my windows go up/down much faster. The radio being louder probably doesn't have anything to do with it though ;D