blowing alternators

E

emrliquidlife

True Classic
So tonight my voltage gauge drops to nothing. Lights dim etc. 20 miles later, the voltage comes up, lights go bright.

Drive home, 10 odd volts according to Mr. Droopy the volt meter in the dash. For about five miles voltage comes back to normal.

Belt tension is fine, alt was replaced successfully 3 months ago.

I will get voltage readings shortly. Any ideas? Is there a off alternator regulator? Car is an 85 Bertone

Thanks,

Ed

PS, JJ, if you see this PM me ur number
 
First thought (no research, no heading out to the test mule, etc) is the regulator is heading south and giving you a nice warning. I'd have to crack open the manuals to see what the checks are what the readings should be...
 
It depends. On some cars, it is. On others it's on the firewall or on the right side of the engine bay.

I just noticed Gregory's post. I'd start there, too.

Also found the specs in the Haynes manual (I know, flame me if you must! :eek:) and it says: Resistance between positive terminal and ground at 77degF: 85 ohms, plus or minus 4.5 ohms.
 
I went through this recently. Thread
synapsis; I put on a shorter belt to insure tension and cleaned up the contact points at the alternator (small spade pulled off, blade sanded lightly, large lug loosened and retightened). Voltage is constant now (well honestly there was one brief moment of voltage drop since then). No idea if what I did helped or if I too have regulator/alt starting to poop out. FWIW Could be slippage under wet conditions as I have no belt splash guard it seems.
 
IMPORTANT QUESTION

Did the red charge light come on ever?

Side note: does your red charge light come on before you start the car? Make sure the light actually works that way.....
 
In my case, yes the light always came on with the key on, before start, it actually stays on until the revs come up a tad, then out and never on again, even with very low voltage readings.
 
Ed, just to humor you a little

What you describe could very-well be a bad brown wire coming off your battery terminal to your fuse block.
Also, this could also be an intermittent connection in the plug inside your steering column. (the one with 2 brown wires going into it.)

Check both these points carefully. If the connector inside your steering column housing looks burnt, fix it (and the connection)

If you haven't already added another 10Ga brown wire from your battery to your fuse box, do it.

Doesn't sound like an alternator problem as much as a power distribution problem.

Poor-man's way of checking the alternator wire to the battery:
Disconnect the large wire coming from your alternator and connect it to a battery charger's positive lead. Ground the battery charger's negative lead to the engine or chassis somewhere.
Stick a volt meter across the battery up front and you should see a minimum of +13 volts or more, and it should be stable. (not varying up and down but up slowly is normal)

These tests will cost you nothing and adding the wire will cost you under 5 bucks on a bad day. :eek:

Good luck Ed!
 
Grrrrr. I tapped the top of the voltage regulator which resulted in positive results after a few miles.
But Mr. Droopy the sad voltage meter showed up after some 30 miles.

Voltage at the battery running is 12.8 and when the radiator fan kicks on it went up a bit to 12.9. With the lights on it was 12.9.

I am going to take Bob's advice above, but does this show me that the issue is wiring? It is strange because the voltage drop really does make the lights go dim. Bad wiring?
 
I've read thru this and am a little confused... so does it seem like the alternator is bad again? Or is more likely the car having some other 'connection problem' simulating a bad alternator?

I'm curious because I've got a non-Fiat (91 toyota base truck) that has 'popped' 3 alternators in 16 months. Everytime I take the alternator out and get it tested at 'autozone', it fails the 'diode test' according to their machine. (or something like that... ) It's been replaced under warranty the last 2 times, but I'm getting frustrated changing out alternators every few months. (I'm getting nascar fast at it!:rolleyes:) But I'm convinced something in my trucks 'wiring' must be 'frying' the diode inside the alternator...
 
Ed... The voltage regulator that you refer to is ...

bolted and soldered to the back of the alternator... kinda built in, on most Bertones.

I believe you need to pull the alternator (through the rear access panel) and take a good look at it. Make sure it and the brush holder is tight and then have it tested at Auto Zone...

The output should be 13.8 to 14.1 volts so I doubt it is functioning.

Bob Brown's ideas could be valid here also... but I believe since you seem to be showing hardly more than BATTERY voltage (12.9 you said) on all your tests that makes me suspect the alternator.

Call if I can help... and if it is the alt, maybe you might wanna convert to GM and forever hold your peace. Oh, and sorry to hear of your trouble...
 
Makes sense...

When the brushes, which are part of the regulator, wear to the point of being too short, you can get symptoms like yours. They just don't have the length or spring pressure to maintain firm contact against the armature. IIRC the minimum is 3-5mm.

This is an image of an internal regulator brush holder from Midwest-Byless:
voltage.regulator.81on.economy.jpg


This is an image of an external regulator brush holder from Obert's site:
9927729.JPG


Here's a bad brush holder/regulator (from Dr. Wifey's BMW or my VW):
IMG_9462.jpg


This is assuming all else like warning bulb, wiring and belt are good. Pay special attention to the connections between alternator and starter, as a loose connection (like between wire and crimped connector) will create a lot of resistance and eventually burn up. Check the ground side of everything as well. Good luck.
 
!

Popping diodes is a symptom of overheating or intense vibration. A diode is just a piece of ceramic that only allows voltage flow in one direction. Converts A/C to D/C.

Make sure that your Alternator stays cool and the fan is turning the right direction. On the X, make sure that cooling tube is attached so the exhaust heat doesn't destroy the alternator. Bad connections also destroy solid state stuff.

I really think on the X, the ignition switch connections can cause some freaky electrical craziness that looks like the alternator is failing. And furthermore, the electrical SPIKES caused by the crappy connections in the switch can cause the regulator to fail.

Suspect anything, check EVERYTHING.
 
This all great input, thanks brethern.

I haven't had time to work on it yet. This all annoying because this is a new alternator. I can't imagine the brushes are worn unless they are defective.

I did take off the steering column plastic. Just jiggling it makes the voltage move what appears to be 3-4 mm of needle movement.
 
GEEZ Eddie... The cover???

I think your problem is more likely what Bob Brown mentioned... look at the ignition switch and its CONNECTOR below the dash... as its probably fried!

If they prove to be OK... then... as for what Eddie said... it all applies especially if your NEW (?) alternator is a stock replacement Bosch or Marelli, as their internals are very sensitive and fragile, NEW or not.

I think there is another FIX out there, somewhere... can't seem to remember what it was though...
 
Yes, precisely

If you look inside that area you'll actually see a spare terminal a-wait'n for ya. :)

It's a tight fit but it'll go in just like the photo shows.

I took that photo several years ago BTW.

Good luck!
 
Thanks for the photo. I knew I should have slown down to give props!

I don't have the white and black plastic bits in my car, it appears that a red wire has been soldered onto two brown wires. I have a metal bracket that runs along the length of the relays that are all metal. This bracket turns at the bottom at a right angle and has two threaded posts to mount the white and plastic bits I am missing. So, attach a power wire to that post?

Don't worry, I'm working slow and w/o the aid of long necks to get this done proper.

Last bit, so I just hook another power wire (from the battery) up to the brown wire closests to the ignition switch right?

Ed
 
I think I may have fixed the old girl.

I started at the battery, made new grounds, prepared for a wire from the hot side to the ignition and to the fuse box. I cleaned the conacts in the ignition wire molex.....

All the while I didn't want to open the brushes from the alt because..."its new!"

Finally took the brushes out...they looked awful. In less than three months they were worn down. One with a really odd pattern.

Pics to come tomorrow. Tonight, I eat Panda Express. Time to get outta the warehouse and test drive her.
 
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