Bad Alternator? Or Bad battery?

91BLOWNSC

Registered User
Within the last week or two, the battery in my car has slowly lost its ability to turn my car over. It was fine, but as time goes on each morning, or after it sits for a while, it turns over slower and slower until this morning when the damn thing just wouldn't start. So I went out and got our truck to jump it, and she started right up. Well I put voltmeter on it and it was charging at 14.3 volts. I drove her to school; a good 6-7 miles down the road, and it barely started 1-2 hours later. I am just verifying that this is my battery that is dead? The only reason I question it, is if i start my car up right, let it run, shut it off and restart it right away, it starts much easier than if it has been sitting. Any thoughts? Thanks. I also have a bad miss at idle. Could there be any correlation between the two?
 
Have the alt checked to see how many amps it is putting out and take your battery in and see if it checks up good or bad. And stop driving and jumping it before you do end up burning out the alt and the battery. Get them checked and then you will know. It is possible for an ALT to put out enough volts but not enough amps to keep the system fully charged.
 
Easiest thing to do is to clean your battery posts and clamps with steel wool, be sure they are tight, but not overly tight, check the battery cells by popping the caps off and looking at the amount of fluid in them, and then charging it up overnight with a trickle charger. If it doesn't take a charge, take it to an auto parts store and have it tested. They sell a cheap bulb type tester you can use to check each cell for charge. From the sound of it, your battery may be bad. 14.3V points to the alternator as being good. Given how hard it is to pull the alternator, I'd have the battery checked first.
The miss at idle probably has nothing to do with the battery.
 
The alternator can be checked while it is on the car at any good parts store. It will give you a peak amp reading and average volteage reading from the alt.
 
Good thing to know. The Azone here has a bench tester so to have it tested (the original one, and the 2 replacements), I had to pull the thing off and take it in.. big pain
This is why I recommend people try to avoid rebuilt alts. Thats not always possible, but if you go with a rebuilt, expect to go through a few before you get a good one. Also keep a cell phone handy for when it goes out, drains the battery, and leaves you stranded on the side of the road somewhere ;)
 
your AZ should have had the portable machine to take out to your car. And yeah, if you go to Autozone, always get the reman lifetime alt, or the Brand New lifetime alt. Never buy the one year, no matter how cheap it is, unless you are selling the car in a week.
 
TbirdSCFan said:
Good thing to know. The Azone here has a bench tester so to have it tested (the original one, and the 2 replacements), I had to pull the thing off and take it in.. big pain
This is why I recommend people try to avoid rebuilt alts. Thats not always possible, but if you go with a rebuilt, expect to go through a few before you get a good one. Also keep a cell phone handy for when it goes out, drains the battery, and leaves you stranded on the side of the road somewhere ;)


You say to avoid rebuilts....I'm assuming you mean remanufactured....Does anyone make new alternators for this car. I have never been able to find a new one. They're always remanufactured. Even the Motorcrafts are remanufactured. If new ones are available, I'd like to know where I can get one.

Thanks,

David
 
kendall221 said:
You say to avoid rebuilts....I'm assuming you mean remanufactured....Does anyone make new alternators for this car. I have never been able to find a new one. They're always remanufactured. Even the Motorcrafts are remanufactured. If new ones are available, I'd like to know where I can get one.

Thanks,

David
Unfortunately for our make and years, you have to look hard to find a new one. :( From there, IMO, I'd take my chances with a used one from a seller here over a rebuilt one. It took 3 replacements for me to get as good one. Each one would last for a month or 2 and then start dropping out. You could see it with a volt meter, if you happen to have one hooked up :rolleyes: A loss of battery power on a car that uses a lot of it is not fun. :(
 
Sounds like the battery. I've had to replace mine every two years since buying the car in 93, and this last one only lasted one year. The new one I got last month looks goofy with all the bright yellow plastic (Duralast).

David
 
The stock alt is very sensitive to overheating and damaging itself if it has to charge a battery all on it's own. Get that battery tested as soon as possible. If the battery is more than 3 years old, don't even bother to test it... just replace it. Just make sure the replacement is fully charged before hooking it up. Once you have a fully charged bat in there then have the alt checked to make sure it's putting out a proper voltage and didn't get burned up.

If you're in a fairly well populated area you can likely get your Alt rebuilt for a cost that is lower than the cost of a reman or rebuilt alt from Autozone and the like, plus it's likely going to be more reliable. Local rebuilders of alternators can usually get the job done for about $100 or less and tend to be high quality. Most of the stuff these guys rebuild are industrial motors and semi-truck size alts.
 
David Neibert said:
Sounds like the battery. I've had to replace mine every two years since buying the car in 93, and this last one only lasted one year. The new one I got last month looks goofy with all the bright yellow plastic (Duralast).

David
My last Duralast 7 year battery last for 5 or 6 years. Thats remarkable considering the Texas heat. :cool:
 
TbirdSCFan said:
My last Duralast 7 year battery last for 5 or 6 years. Thats remarkable considering the Texas heat. :cool:

Mine would probably last a lot longer if the car was driven more often.

David
 
Lifetime Warranty Remans and Walmart Batteries!!!!!!

I just went through 4 alternators on my XR7 in 4+ years and 2 alternators on my SC in 2+ years. Fortunately they all had lifetime warranties. My XR7 had other issues. The alternator charging wire that connects to the starter relay had melted the black sealer at the crimp junction causing a high resistance connection. I replaced the lug and all is well. On my SC, since I have a rough idle probelm I cannot seem to fix, I have had to put the factory pullies back on. My low voltage radar detector alarm kept going off and I believe that constant low voltage at idle with a high load on the alternator lead to the death of the last alternator.

I have Walmart MAXX batteries in everything. Cars, trucks, farm equipment and boats. For $60 and a free 3 year replacement, you can't beat them. I have about 15 Walmart batteries in use and have only returned 1. Also, Walmarts are everywhere so replacement is not a problem.

Just my 2 cents worth!

Ed Springer

90 Black XR7 5-speed: 70mm TB, Fresh Air Intake, '94 Supercharger, 5% SC Pulley, Raised SC Top, I/C Fan, UD Pulleys, 190 l/h Fuel Pump, 36# Injectors, Headers, Magnaflow Muffler (no cats) with stock resonators, 3:27 Gears, Ripper Shifter, 73mm CL MAF (Blue Tube), Magnacore Wires, NGK Iridium Plugs, Royal Purple Lubricants and Rear Spring Air Bags.

94 Red SC Auto: 70mm TB, Fresh Air Intake, Stock 90 SC Pulley, Raised SC Top, I/C Fan, 190 l/h Fuel Pump, 38# Injectors, Headers, Raven Muffler (no cats) with stock resonators, 3:73 Gears, 76mm CL MAF (Gold Tube), Magnacore Wires, NGK Iridium Plugs, Royal Purple Lubricants, TRANSGO Shift Kit, Pro-Torque 2500 Stall TC, Haydon Auxiliary Transmission Cooler, Tokico Struts & Shocks, American Racing 17” Sniper Wheels, Michelin Pilot Sport A/S Tires and 235 RWHP with 315 LB-FT Torque.
 
As I was getting some parts this last weekend at Ford and just for giggles, I asked the parts guys for a price on a new alternator from Ford. He claimed 170.00 USD! I was amazed. I would hope that it's not a rebuilt one as someone claimed earlier. My alternator is putting out 13.8 volts to the battery and when hooked up to the battery charger (with it off of course), the meter on it reads right on the line between yellow (might think about getting a replacement) and green (good). So I figure that I might need a new alternator soon. I'm thinking that I'll just buy a new one from Ford!
 
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