Bad Alternator? Need Advice

97 GT w/50,000 mi., 4.6 with stock everything, A/T. On the way to work this morn I noticed my headlights were dim and when I parked, sure
enough, give it some gas and they brighten and voltage meter goes back up. When in drive and stopped (on the brake at a light for instance), noticeable drop on the volt gauge but when put into neutral, gauge goes back to mid point. Also, as soon as I let off the brake and give it the slightest rpm's, gauge also goes back to norm (mid point). What gives? My experience tells me alternator but I wanted to query the masses (i.e. those smarter than me). I was wondering if this is normal for our vehicles since I did find some old posts about this problem, and they indicated that some people just live with it (after throwing parts at it of course) Please enlighten me...... Did I mention you guys are smart? Thanx T
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Is the battery working OK or have you killed it? Sounds like voltage reg as a possibility, and much cheaper!
--
Scott W.
'66 HCS Mustang 289
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Nope, batts fine.... haven't killed it and car starts right up

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Sounds like a regulator to me. Take it to Checkzone Boys and have'em hook it up to see if it's charging correctly. Problem is they'll sometimes tell you it's the alt when it's really the voltage regulator. Trust me, I know. Checker tried to sell me a $100 alt instead of the $12 regulator. It was the regulator. Course mine is a '68, not a modern car, so I don't know FOR SURE.
--
Scott W.
'66 HCS Mustang 289
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
It's the alternator..
Take it off and have it load tested at autozone.
Could be brushes or reg or even diode block
I recently had most of the diodes in my rectifier assy blow and had a helluva time making it home at night.. fortunately was on a freeway... had to kill headlights to get batt charged back up every few miles.
Test: difference in volt reading headlights on/off.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Great..... I was afraid of that.
Backyard Mechanic wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I did notice that after starting the car, this problem doesn't appear for about 5 mins or so. Volt guage is normal. It's only after running for a bit it starts happening..... Does this have any bearing on the problem?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I did notice that after starting the car, this problem doesn't appear for about 5 mins or so. Volt guage is normal. It's only after running for a bit it starts happening..... Does this have any bearing on the problem? Also, the waterpump was just replaced (not by me, dealer warranty), is it possible something didn't get connected properly?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I did notice that after starting the car, this problem doesn't appear for about 5 mins or so. Volt guage is normal. It's only after running for a bit it starts happening..... Does this have any bearing on the problem? Also, the waterpump was just replaced (not by me, dealer warranty), is it possible something didn't get connected properly? As far as I know, one has to remove the alternator to replace the waterpump.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

While it may be the alternator, as suggested previously, it may be something else too.
I am speaking generically, and am not familiar with the exact system your car uses but:
- Be sure to check the condition of the belt and the tension. A slipping belt, due to burnishing, grease, other contamination can cause problems. If you have a serpentine with tensioner, be sure that tensioner is installed properly and working as it should.
- Be sure your cable terminals are clean and are properly connected to battery, alternator, starter, ground points etc. Dirty or loose cables are another big mess.
- While Autozone will happily test your alternator, think twice before buying one of their rebuilt units. They have a lifetime warranty, but are not highly praised in the pits. Doesn't mean you have to buy from Ford either.
- If a regulator is bad, then the replacement is a cheap and relatively easy fix.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanx for all the help everyone, you all are the best! It's nice to know that there is a forum for questions such as these. Drive/ride safe, keep the rubber side down! T
snipped-for-privacy@nospam.nix wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.