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jdca4503

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Reply with quote  #1 

For some unknown reason, the voltage on my 73 Super increases at all different times while sitting at idle in traffic, and when driving.  It's more apparent when cold.  An example is: sitting at a traffic light.  My voltmeter shows charging at around 12.5 volts.  Then, for some reason, I get a spike and it pegs the volt needle at 16 volts!  Then when it's ready, it goes back to normal reading.  I have asked my mechanic to look into it, but he cannot demonstrate the problem, and has told me on at least two occasions, that everything checks out.  But it's not true!  I know this spike in volts is interferring with performance and economy, and it's not good for everything else!  Since the alternator has an internal regulator, I'm thinking that it's the alternator. But since my mechanic says he can't demonstrate the problem, I don't want to be a parts replacer only to find out that was not the problem.  Do any of you have any ideas?  I'd surely appreciate it. Thanks.  Regards, John 

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dizi

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Reply with quote  #2 

is your belt at the right tension or is the belt worn out and are either of your pulleys bent. If not then it would be your regulator going bad, and you should be able to swap it out 


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olspeed

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Reply with quote  #3 
First off 12.5 volts is a little low, should be up in the 13 to 14 volt range. This allows the Battery to charge while still running lights and other things. I would take your Alt off and get it checked at a electrical shop that specializes in rebuilding electrical components as they normally have more and better testing equipment than the average mechanic.
Olspeed

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68autobug

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Reply with quote  #4 
Hi
I used to have that problem years ago with an alternator with an external regulator.. it was in a Australian Made Mitsubishi car..  What actually happens is the voltage regulator is breaking down allowing AC [alternate current] to flow instead of rectified DC {Direct Current] which is needed to charge the battery etc...
The alternator does put out 16+ Volts AC before it is rectified into DC...

seeing You have an internal rectifier in Your alternator....  I believe that is the problem...
You could test this with a multimeter.. using the AC function when the alternator is putting out AC 16+ volts...

and an alternator should put out 13.8 - 14 volts DC normally without any headlamps etc on...The AC makes no difference to the light bulbs in the car apart from being a bit brighter... but won't charge the battery..

cheers

Lee in Australia

http://community.webshots.com/user/vw68autobug





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bob

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Reply with quote  #5 
Those AL82N alternators have an internal voltage regulator, which can be replaced. the part number is IB359 and will cost about 20 dollars. It is also nice if you have an extra alternator with fan, back plate, T clamp and pulley ready to go, just in case
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68autobug

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Reply with quote  #6 
Yes, it would be great to have a spare alternator ready to fit but they are still expensive here in Australia especially for a good one. Chinese made alternators are cheaper but I don't really want a spare one of those.
Interesting about the regulator replacement.. I will look into that.
I already have new brushes to fit.

cheers

Lee in Australia






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bob

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Reply with quote  #7 
Then you can do what I did. Find one at a VW Show or junkyard and rebuild it yourself. The Bosch ones can be easily rebuilt. I usually replace all the screws with stainless, check the bearings for play. I hate the shims for the pulley and replaced with serpintine belt kit making sure to use a locknut on the pulley.
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68autobug

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Reply with quote  #8 
Hi
Well the serpentine belts are much better but they cost about 3-4 alternators over here. The vw belt system must be a very old invention 
.. for pulleys that cannot be adjusted like the beetle's. You can buy stainless steel shims in the UK.. but its still the ancient belt system which can't be good for the belts.

an alternator belt is 11.3mm x 912mm long but a generator belt is 9.5 mm x 900 or 905mm long and they use the same pulleys.. one adjustable [generator or alternator] and one with a fixed width [crankshaft pulley]..

I have always used alternator belts but many vw shops are now selling the two belts under one part number...
so, You can get either... lol  true..

cheers

Lee

PS. originally the alternator belts were much much stronger and did not stretch due to their different makeup/design..
Lee




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bob

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Reply with quote  #9 
Hi Lee
I understand the price but the reliability far outweighs the cost. For 5 years I have run BMD pulleys on my 68 Dune Buggy and 74 Super Beetle with no problems. This whole problem could have been fixed long ago if VW would have use left handed metric threads on their alternators, generators and engines that turns clockwise. When the Chinese copied the design, they could have improved it too but didnt. This is the main reason so many people have problems with their pulleys.

Bob
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68autobug

VW Guru
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Reply with quote  #10 
Hi again

Yes, not much has changed in 40-50 years... lol
and the chinese aren't doing too good at copying a lot of things. They can make the parts smaller or larger or thicker
or thinner as they have no idea what they are making.. lol
One fellow in Australia has a new alternator with no keyway to hold pulley.. lol
   people who sold it to him said it was a new modification..?   I see parts are now being made in India, I just hope they know what they are making..

cheers

Lee in Australia

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