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voltage drop

jeepnuts311

NAXJA Forum User
Location
Atlanta, Georgia
hey all,

at idle, my voltage is great. It stays about 13ish and all accessories run great as well.

when i rev it, the volts drop and then come back at idle.

at driving speed my volts remain a constant 10 volts. the headlights dim whenever the blinkers blink, etc. the problem is there during day when the headlights are off, as well as night when they are on.

alternator is about 2 years old and has never given me any trouble (the bearing went out on the previois alt) the battery is an optima and cranks just as fast as ever, and pulls the winch strong too

only clue i have is a terrible timing chain cover leak which may get the alternator dirty. i cleaned the alternator with steam pressure and also electrical cleaner and it had no effect.

any ideas?

-TIm
 
clean all your battery cables and ground cables.
 
the belt does squeal a little sometimes....never thought of that....but the alt doesnt have that much resistance does it? wouldnt the PS or water pump slip first? why does it drop as soon as i rev it and the come back?

-tim
 
jeepnuts311 said:
the belt does squeal a little sometimes....never thought of that....but the alt doesnt have that much resistance does it? wouldnt the PS or water pump slip first? why does it drop as soon as i rev it and the come back?

-tim

Yes, the alternator does have that much resistance, especially if it's fighting to bring a low battery up. That's why belts often squeal when you start up cold or turn on all the lights, but then stop later. The alternator load decreases when demand does. If it's squealing it's certain that the belt is not tight enough, or is slipping due to oil fouling, or both.

The water pump uses very little power, and if it slips you probably won't notice unless you're running hot already. The PS might also be slipping, but it is almost always putting out more pressure than you need, and bypassing, so you probably won't notice it until you try to do an emergency move and find that there's no boost.
 
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