What can cause an alternator to go bad? - Team Camaro Tech
Team Camaro Tech join team camaro
 
Camaro Parts at SS396.com     
GROUND UP & SS396.com         
Official Sponsor of Team Camaro
   

Auto Insurance



Registered users (free) do not see these large ads

Electrical & Wiring Troubleshooting electrical.

Reply
 
Thread Tools Display Modes
  #1  
Old Feb 26th, 06, 09:42 PM
BEbengali BEbengali is offline
Tech Team

 
Join Date: Feb 2006
Posts: 33
Default What can cause an alternator to go bad?

Besides being old or having a lot of miles, what can cause an alternator to go bad?

I did a battery voltage test, and the CCAs and voltage are perfect.
The only thing I can think of is that since my headlight bulbs suck, I have always had the brights on when driving at night. I will be getting new xenon lamps/bulbs as soon as the paint and body is done.

Could driving with the brights have been the cause?

Story: Bought a '68 two weeks ago, drove it home at night and the battery got drained when using the head lights. The headlights got really dim, and I heard and felt thumping under medium to heavy throttle. It kind of felt like the engine was bogging. I pulled over to park, and the motor died. It would not even turn over when trying to start it - just clicking. I replaced the alternator two days later with a GM remanufactured alternator, and the car ran perfect (even with headlights on) for almost two weeks. Then last night, I felt the same thumping, and noticed the headlights getting dimmer.

I'm going to buy a brand new alternator tomorrow, instead of getting another reman.

Thanks for the help,
Brian
Reply With Quote
Sponsored Links
Advertisement
 
  #2  
Old Feb 26th, 06, 09:59 PM
Camaro Dave Camaro Dave is offline
Senior Tech

 
Join Date: Jun 2005
Location: Sunny So. Cal
Posts: 3,064
Default Re: What can cause an alternator to go bad?

After you put the new alternator on, did you check the alternator's output? Grab a voltmeter and check the output to the battery and see if it's charging at 13-14 volts. Another problem might be the regulator. Also double check all the connections at the alternator and regulator.
__________________
67 RS Camaro 327/ 350 Holley 650cfm > Edelbrock Performer Intake > Pertronix Ignition > Accel Super Stock Coil and Wires > Hedman Hedders > Hotchkis Performance Springs > 15" Rallys all around

Camaro buds until the end!!!
Reply With Quote
  #3  
Old Feb 26th, 06, 10:07 PM
dyno jonn dyno jonn is online now
Senior Tech

Jon
 
Join Date: Dec 2002
Location: Back in the USA.....
Posts: 2,309
Default Re: What can cause an alternator to go bad?

Be sure your battery is good too. A bad battery can eat an alternator in no time flat!!
__________________
Jon N.

The only reason someone would want insurance is if they want to pay someone elses bills or want someone else to pay their bills.

Liberalism is the belief that "Evil Deserves a Fair Chance".
Reply With Quote
  #4  
Old Feb 27th, 06, 12:41 AM
Steptoe Steptoe is online now
Senior Tech

Steps
 
Join Date: Dec 2005
Location: New Zealand
Posts: 12,814
Default Re: What can cause an alternator to go bad?

There is nothing wrong with reman alternators...so long as they are rebuilt correctly and not on the cheap...too often, diodes, bushes are replaced and something like bearings not..or the main shaft is not turned down in a lathe.
There is not reason for this to be done...parts are cheap and basically boils down to lazyness. I rebuild my own, then I know its done right like most things.
A crook altnerator can/will screw a battery..always check outputs when putting a new one in and also when putting a new battery in.
Sort of like when putting on a new set of tyres, always get a wheel alingment
Reply With Quote
  #5  
Old Mar 1st, 06, 01:31 PM
BEbengali BEbengali is offline
Tech Team

 
Join Date: Feb 2006
Posts: 33
Default Re: What can cause an alternator to go bad?

Thanks for the help.

I did a battery voltage test after I put the reman. alternator in, but I disconnected the terminals first.
I just bought a brand new alternator, so I'll check the output to the battery once I install it.
If the problem still exists, I'll check the regulator.

Also, do you think using the brights could have caused it?
Any more suggestions?

Thanks
Reply With Quote
  #6  
Old Mar 1st, 06, 02:29 PM
dragon0123 dragon0123 is offline
Senior Tech

Mark
 
Join Date: Mar 2001
Location: Janesville, WI
Posts: 600
Default Re: What can cause an alternator to go bad?

Quote:
Originally Posted by BEbengali
Thanks for the help.

I did a battery voltage test after I put the reman. alternator in, but I disconnected the terminals first.

Thanks
Disconected the terminals of the battery while the car was running??

Pretty sure your not supposed to do this.. Ive heard that it may burn out the alternator.
__________________
Mark

1967 Camaro

My Photobucket >> http://s145.photobucket.com/albums/r239/camarodragon/
Reply With Quote
  #7  
Old Mar 1st, 06, 02:59 PM
Marktat Marktat is offline
Gold Lifetime Member

Mark
 
Join Date: Mar 2001
Location: NJ
Posts: 477
Default Re: What can cause an alternator to go bad?

Never run an alternator without being hooked up to the battery...or its bye bye diodes in the alternator.
Reply With Quote
  #8  
Old Mar 1st, 06, 07:33 PM
BEbengali BEbengali is offline
Tech Team

 
Join Date: Feb 2006
Posts: 33
Default Re: What can cause an alternator to go bad?

Quote:
Originally Posted by dragon0123
Disconected the terminals of the battery while the car was running??

Pretty sure your not supposed to do this.. Ive heard that it may burn out the alternator.
No no, haha. Engine was off. I just disconnected the terminals because I wanted to test the battery, just to make sure the cold cranking amps and voltage were good. Removing the terminals just gives the voltmeter a cleaner reading.
Reply With Quote
  #9  
Old Mar 1st, 06, 07:49 PM
JimM JimM is offline
Gold Lifetime Member

Jim
 
Join Date: Dec 1999
Location: Yorkville, Illinois USA
Posts: 22,119
Default Re: What can cause an alternator to go bad?

rather than throwing alternators at it, you might check the regulator.
You didn't mention your GEN light. Did it come on? Does it ever come on? It should glow bright when you turn the key on but don't start the car, and it should glow dim with the key in accessory. A burned out GEN light, or any other probl,em in that circuit can cause the alternator not to charge, or not to charge well.

Check the connections at the alternator and the regulator. Clean the contacts with steel wool.

Let us know what the GEN light is doing, or fix it.
Charge the battery and do some proper testing.

Running the car without the battery connected is a fairly handy (tho somewhat dangerous) way to verify that the alternator AND regulator are putting out at least something. I've done it, more than once, and it hasn't cost me a part yet.

Got a $20 that says both alternators are good.
__________________
JimM's firstgens.com Camaro Board

Jimragtop.com New website for my vert is coming together. Do ya like the slide show on the home page?
Reply With Quote
  #10  
Old Mar 1st, 06, 07:52 PM
Steptoe Steptoe is online now
Senior Tech

Steps
 
Join Date: Dec 2005
Location: New Zealand
Posts: 12,814
Default Re: What can cause an alternator to go bad?

Quote:
Never run an alternator without being hooked up to the battery...or its bye bye diodes in the alternator.
A short period of a few seconds and not reving the engine u will get way with it.
Another thought, anyone been welding (Electric)on the car without disconectig terminals? Can screw alternators and sometimes the battery.
Going flat overnight...turn the ignition to lock, place an ammeter between the +ve battery terminal and clamp. There should be no current, or a very small one if u have theft alarm.
If u do have a current it is then a matter of following thru to fuse box to find out where/what is drawing it.
I ran into this a few yrs back, installed an aftermarket radio, and connected into the cigarette circuit so I could play with the ignition off. I did not realise that althu off the radio still had operating functions running in the back ground.
If the ignition is in the acc position u may have a drain from accessories that are on.

Flattening out batteries doesnt do them any good either. So if u have a problem of this nature, make good use of a charger...further note...some chargers will not charge a battery under a threshold of 8 to 9 volts, as they are designed to assume the battery is a dud. To get around this, place your battery in parrell with another 12v, charge for 1/2 hr..they voltage will then be above the threshold, and the other battery removed.
Reply With Quote
  #11  
Old Mar 2nd, 06, 04:09 AM
Everett#2390's Avatar
Everett#2390 Everett#2390 is offline
Moderator

<Jake 68's Rule
 
Join Date: Sep 2000
Location: Va Beach VA
Posts: 27,192
Default Re: What can cause an alternator to go bad?

Lots of good suggestions given. Be sure the battery cable connections, at both ends , are clean and in good condition, no broken strands.

We should know what set up your car has, is it stock OE charging system or has the external regulated alternator been replaced with an internal regulated alternator?

Looking at the alternator rear side, there will three wires, one large red wire to BAT terminal and teo other wires in a connector If the wire connector has the connection like so: II , then it is an external regulated charging system. If the connecctor looks like this: -- , then it is an internal regulated charging system.

All charging system voltage checks should be done at the battery posts with the engine running at appproximately 1500 rpm. On an external, with lights on, heater on, radio on, charging voltage should not be below 13.5 volts. If you have an internally regulated alternator, charging voltage should not go below 14 volts.

As a quick check, measure the voltage from the BAT terminal on the alternator to the positive battery post. This measurement should be less than 0.4 volts. If it is higher, then you have corrosion or a broken wire from the BAt term to the pos post.

The red wire goes from the alt to the horn relay buss bar (drvr side of rad support under the washer fluid bottle). the other connection of the buss bar a red wire across the rad support to a junction block next to the battery, then to a pigtail to the pos battery cable. Any point along this path can be corroded. Remove the connections and clean them with a wire brush. Repair those connections not of good repair.

If you still find charging voltage low, you may want to replace the external regulator with a Wells unit, P/N VR715, an electronic external regulator. The old mechanical ones can get a bit cranky and pitted points inside.
__________________
Give a man a rescued dog for the health of his soul.
'With enough thrust, pigs can fly.' Other Stuff
Reply With Quote
  #12  
Old Mar 2nd, 06, 05:44 AM
SCHOON SCHOON is offline
Senior Tech

Jim
 
Join Date: Aug 2004
Location: Flemington, New Jersey
Posts: 517
Default Re: What can cause an alternator to go bad?

Went through 2 altenators before I realized it was a short in the bat.
__________________
Schoon
Reply With Quote
  #13  
Old Mar 2nd, 06, 12:22 PM
Steptoe Steptoe is online now
Senior Tech

Steps
 
Join Date: Dec 2005
Location: New Zealand
Posts: 12,814
Default Re: What can cause an alternator to go bad?

If replacing non self alternator, think about going to a later model self regulating one...u just dont use all the wires, and less to go wrong later.
When I did mine, I got an old housing and a new set of bearings. Cleaned and polished the housing, the swapped the interals of the new one into the polshed housing...that way the car was not off the road.
To polish I used a stick of stainless steel polish compound, an electric drill in the vice and a 4+ buffing wheel, kept moist with Kerosene. Safty glasses and old colthes lol
Use an old drill, loading sidways kills the drill brearings, it will not be anygood to drill acruate holes afterwards.
Reply With Quote
Sponsored Links
Advertisement
 
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -7. The time now is 03:17 PM.



Camaros.net - 2009 AutoForums.com