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Old 10-22-2002, 08:03 PM
Posts: n/a
OK .... Help! Help! Voltage Regulator

Changing the V.R.

OK I 've got the car up on jacks and am underneath it....

There are two set of screw holes upper and lower on the alternator.

I had alot of trouble using the lower ones but I got the new VR put in on the upper set. It looked OK so I buttoned it back up and reconnected the battery.

Before starting.... 12.45 volts ok

After starting 12.0 ....11.98 .....

then I turned on the lights 11.90 ...11.89...

and dropping.

So I checked my other two cars 13.5 & 14.2 while running.

I think either I had the VR in wrong or something else...

Obviously the system is not charging....but not warning lights on dash either.

Gonna wait for a reply here....

Please If you can help.

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Old 10-22-2002, 08:31 PM
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Part 2

I don't know maybe its right..?

I re-installed the VR and before starting 12.4 V at the battery

While running 12.0 - to 11.98

I let it run for about 10 minutes to see if it would fall further but it seemed to stay right around 12 V

and when I shut it off ... 12.38 from the battery.

maybe its doing what it's supposed to..but I would have thought I get more that 12 V while running.

I only have 2 fords to compare it to.

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Old 10-22-2002, 08:49 PM
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Sorry to keep spilling my woes on you!

Well I did alot of reading in the archives and it looks as though I am supposed to be getting about 13.5 - 14 volts when running.

So.. It sounds like the alternator is not putting out at all. Just running on the battery.

Looks like new alternator time. $160.00 man!

Does any body have experience changing one of these things?

I can get to it easily from underneath (I've got it up on jackstands) but the serpentine belt ?? ...never messed with one before.

Can the alternator be replaced without jacking with the tensioner?

Are there any tips I should know about?

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Old 10-22-2002, 09:11 PM
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JCE JCE is offline
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Join Date: May 1999
Location: So Kalifornia
Posts: 2,189
If the alternator wasn't charging properly before, your battery voltage under load is going to measure a bit low for a while, I believe. If the new battery was damaged by the overvoltage and acid spewing you described, that may be a source of the 'low' 12 volt reading. (My battery reads about 13.5 running, 12 with engine off.) If it were steadily dropping over time, I would say you were running off the battery and the alternator still had a problem. But since it is holding at 12, and may eventually climb up a bit, the alternator is possibly doing OK. You don't have the overvoltage like you did before the brush change, so no (additional?) damage should occur to the battery. Running it for a while and checking the voltage at the battery may be in order to see what the voltage is doing. Running for a while should show if the voltage is going to decrease (running off battery?), increase (battery charging back up), or staying the same (damaged battery and/or faulty alternator?)

Also, if the battery was spewing, did the liquid get replaced? I would have the battery checked out before I popped for a new alternator.

Here is a drawing of the back of my alternator.

The bottom hex bolts 'A' and 'B' were removed to replace the reg/brush assembly. Is your alternator different?

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Last edited by JCE; 10-22-2002 at 09:17 PM.
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Old 10-22-2002, 09:24 PM
Posts: n/a
Thanks John ....

The Voltage across the battery with the old regulator was 18.7.

The engine ran on the new battery ran for only about 10 minutes before I got home.

It never sizzled like the old one and it's spew was only a drop or two. I really think the new battery is Ok. I will go start the car and let it run for 15 more minutes or so and see what happens.

Here is what my alternator looks like.

It's an 80 AMP Alternator
It looks as thoug there are only 2 bolts holding it in.

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Old 10-22-2002, 09:57 PM
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Here's what I am getting..

This is the place!

Up On Jacks

The Back of the Alternator with the new VR installed

Voltage NOT Running 12.55

Voltage Running 12.02

Though I'd show you!

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Old 10-22-2002, 11:18 PM
Posts: n/a
Good News!!!

I took some advise and ran the engine for a while and some at higher RMP than Idle.

Now...even at idle I am getting 13.33 V!

Woo Hoo!

I think it will get better with time to.
(I hope)

Here is what the old VR looked like...
note the difference in size of the contacts..

Any thoughs ...please feel free!

(I'll be driving with the Volt meter for a while till I feel better) LOL
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Old 10-23-2002, 06:39 AM
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Join Date: Sep 2002
Location: Newcastle upon Tyne, UK
Posts: 215
VR versus rebuilt unit

As an aside, I wonder at the differences in culture UK/US. When my alternator on my 190E went wrong, I bought a rebuilt unit from my local Bosch agent for 38 pounds, say $60. I paid pretty much the same for a rebuilt unit on my beemer.

I've never considered replacing just the VR.

Perhaps this is because Bosch units are used on some very ordinary cars in Europe?

Just an observation
Cheers, Neil

Last edited by neileg; 10-23-2002 at 06:44 AM.
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Old 10-23-2002, 09:50 AM
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Join Date: Apr 2001
Location: Dallas/Fort-Worth
Posts: 5,711
You may be fortunate enough to not have to replace the alternator, but if not, I have replaced mine without too much dismantling.

I got the belt off without messing with the tensioner...I did have to remove the fan for access (3 allen bolts secure it to the clutch). The width of the belt makes install and removal easy. There should be enough slack to pull a bit off near an adjacent pulley, then rotate a free pulley until it works itself off. Did the install in the opposite manner. Hope you have a manual to use as a guide to how it all threads back together!

Two 19mm bolts hold the alternator in place. The bottom on is easy to get to, but the top one requires some effort, as there is little room to move a tool around. This is a knuckle scraping job at this point. I took about 2 evenings to remove the alternator (did the work casually), but it took about 1/2 hour to install everything (alternator, belt, fan) once the alternator showed up at the doorstep.

BTW, your pics show a different unit than the Bosch alternator I obtained. You couldn't replace the regulator as it was internal, so alternator replacement was my only option (Bosch OEM, $160 @ FastLane).

My three-year old battery wasn't damaged by the excess voltage, but I did have to refill a couple of cells with distilled water...
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