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PrOpeller
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707 Posts
Discussion Starter · #1 ·
I'm at my wit's end with this one and hoping somebody has a clue what might be going on here...

Symptoms:
Alternator is overcharging battery at 17+ volts. This is confirmed by my digital voltmeter at the battery and at the alternator b+ terminal. Also, my dash ammeter pegs to 30+ when I rev the engine up.

The problem CANNOT be the voltage regulator, however. I've tried several confirmed good ones and even tried a brand new one with no change. I have also replaced ALL wiring to/from the alternator and voltage regulator and have verified proper gounding of the regulator. I have checked/replaced all my grounds (frame to block and alt to block), and I have cleaned and verified battery terminal connections and fuseblock connections.

Is it possible that there is something wonky inside the alternator itself? Or, that my dash ammeter has shorted somehow to cause this condition?

The car is a 1.1L GT.
 

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Premium Member
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1,802 Posts
wiring

Just a quick double check, it is an alternator, not generator, right?


First step would be to run the car with the plug pulled on the regulator, just to make sure it doesn't charge. If it does, then bad alternator.

Second step would be to double chack the maximum output of the alternator and compare it to what you're getting. This is done by jumpering the D+ terminal on the alternator to the DF terminal, usually with a little jumper wire with 2 male 1/4" spade terminals jumpering the red wire to the black one on the regulator plug. It should peg to a voltage even higher than what you currently get, if not, probably bad alternator.

Last check, to isolate it down to pieces/parts, is to make 3, 8" jumper wires, 2 with a male spade on one end and a female 1/4" spade on the other, and the last with a female spade on one end and a big ring terminal on the other. Install the two matching jumpers betweern the DF and D- terminals on the regulator plug and their terminals on the regulator, the other jumper goes from the remaining terminal (D+) on the regulator to the big output terminal on the alternator. If in this configuration it all works as it should, then one of the field diodes is kaput, and the alternator will need to be repaired/overhauled/replaced.

Or, if you're just plain tired of all this, swap out the alternator with one of these: http://www.partsamerica.com/ProductDetail.aspx?mfrcode=ATR&mfrpartnumber=A134267&parttype=11&ptset=A

You'll have to swap out the pully with a v-belt one, but the chrome universal GM ones they sell at the parts store work fine. Most junkyards sell them for a lot, lot less, just ask for one for an '89 Cavalier 2.8 V-6. You'll get 100A of output and no modifications to the bracketry needed at all. The wiring is a bit different, but if you go that way I'll walk you through it. I also have several, and would be willing to swap the pulley and send it on to you for not a lot of $ either, just PM or e-mail me.
 

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PrOpeller
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707 Posts
Discussion Starter · #3 · (Edited)
oldopelguy said:
Just a quick double check, it is an alternator, not generator, right?
Yes, alternator.

First step would be to run the car with the plug pulled on the regulator, just to make sure it doesn't charge. If it does, then bad alternator.
Strike one...cranks out mucho voltage.

Second step would be to double chack the maximum output of the alternator and compare it to what you're getting. This is done by jumpering the D+ terminal on the alternator to the DF terminal, usually with a little jumper wire with 2 male 1/4" spade terminals jumpering the red wire to the black one on the regulator plug. It should peg to a voltage even higher than what you currently get, if not, probably bad alternator.
I had actually tried this one before per the FSM. It pegs the voltage same as before. Strike two.

Last check, to isolate it down to pieces/parts, is to make 3, 8" jumper wires...
I'll try this tomorrow, but I think I know what the result will be.

Or, if you're just plain tired of all this, swap out the alternator with one of these: http://www.partsamerica.com/ProductDetail.aspx?mfrcode=ATR&mfrpartn.
Nice option which, unfortunately, is not available in this case. It appears the GT1100 has a slightly different case than a standard Opel 1.1L alternator. The mounting ears are in different locations.

That's the main reason I just had this one rebuilt locally. But the shop that did the work was sure it had to be my wiring since "there's no way an alternator can put out too much voltage with a functioning regulator." I didn't believe the guy when he said that, but supposedly he's the expert, right?

Many thanks for the advice, OldOpelGuy! Now I know I'm not going crazy, and I will bring the alternator back to have the diodes checked. Hopefully, I won't have a problem getting it repaired correctly this time. :rolleyes:
 

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Opeler
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71 Posts
Overcharging.

I have seen this before in a rebuilt alternator(about 8 months after purchase) with one of my cars before.The volt .guage was pegged (+).It even trashed my radio.I had to get another one but luckily it was stiil under warranty.You also should have the shop redo a continuity test on the windings of the armature.A short there could cause the current to bypass the diodes and give you that surge of voltage.Most likely they just turned the commutator and put in new brushes and bearings and thought your regulator could handle that kind of voltage.I am sure they had to guess at the OEM output of this alternator since it has no internal regulator and it is a 1.1(scarce to find specs on).I would also take the regulator with you so they can match the output current from the alternator (ie: new diodes possibly).Good luck and have patience.They will know what is going on with your Alternator.
 

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Premium Member
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1,802 Posts
PROPEL said:
It appears the GT1100 has a slightly different case than a standard Opel 1.1L alternator. The mounting ears are in different locations.
Could you pop the bracket off and snap me a photo of both the alt and the bracket if you do end up replacing the alternator? I ask because the part #'s for the GT 1100 and the Kadett Rallye 1100 alts are the same in my book. I have a couple of the Kadett 1100 alt brackets too, so it still might be an option if you decide you want to persue it.
 

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Opeler
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51 Posts
Double check

I do not know what kind of tester the shop used. I do know a any Checker, Schucks, or Kragen will have a really nice computer controlled tester that takes in account for external regulator. I believe Advance and Zone have this new macine too, I recently saw one at zone and Advance is a partner with CSK. The machine tests Diode ripple lamp on/off volts and will show a defective if voltage is above spec. Okay, so I work at Checker but this machine really takes out any guesswork. We also have a hand held unit to take out to the car, but you probably don't want to drive it with those readings.
HTH,
Shawn
 

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Member
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352 Posts
Bad battery?

WARNING: Newbie input follows-(correction of error in my thought is welcome) :) :

Since PROPELs regulator is a thermo-type relay, couldn't a fused-cell battery be unable to store enough amps to heat the regulator wind and trigger the charging contact open? ...thus higher than desired voltage at battery? Maybe have the battery load tested. (FWIW- new/defective batteries are not totally uncommon).

-Dan
 

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Opeler
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71 Posts
Fused Cell.

Sorry! Also a lower amp to not trigger the right combo of contact/no contact would just cause the contacts to ocsilate back and forth at a different rate than it would at higher amps but there is a limit where the contacts just cease to oscilate and that is caused by over charge from the alt.A dead cell would cause the output of the battery to be diminished.Would eat the charge.Also a dead cell battery would not hold a very good charge for long(even a overcharge cannot make up for a dead cell).The spike in power is definately from inside the alt.Besides you would get a low output reading from the battery not a higher one like he is getting.
 
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