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Re: new voltage regulator, but still only charges at idle Posted by Ari [Email] (#2847) [Profile/Gallery] (more from Ari) on Thu, 6 Jan 2005 13:34:25 In Reply to: new voltage regulator, but still only charges at idle, rob [Profile/Gallery] , Thu, 6 Jan 2005 02:53:02 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I'll assume that you see the same effect (voltage drops) if you simply rev up the engine - that the voltage drop is a function of engine speed, not road speed.
Was this the same symptoms that caused you to replace the VR in the first place? If so, it may not be the VR - you could have a loose internal connection in the alternator, and a bad diode is what comes to mind. The best way to diagnose a diode is to stick an oscilloscope, which most good automotive shops should have. Many autoparts stores can do the test.
Assuming the diode is OK:
I'd go with two possibilities - a non-Bosch VR, as mentioned, or that the commutator on the alternator is chewed up. The third of the two would be a slipping belt.
If you run the brushes down, they can start to chew up the commutator - the metal bits on the armature that the brushes ride on. If those are rough, as the alternator speeds up, the brushes start to bounce, and if they're not making contact, the alternator won't work. The same if the springs on the brushes are weak.
That's not to say that an Out-Of-The-Box Bosch VR couldn't be bad. Nobody has a perfect record.
I would first do a visual - when you rev the engine, does the alternator pulley keep spinning? Do you see anything vibrating 'too much'? Next, I would remove and inspect the VR brushes - are they chewed up? Did it go in right (it is a blind fit). Are the springs springing? If it looks just fine, and all the wires are still hooked up well, I'll think about dropping in a new VR.
posted by 12.76.155...
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