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Author Topic: Alternator on the way out?  (Read 1659 times)

Offline cox

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Alternator on the way out?
« on: 12 January 2009, 10:13 »
My mk2 gti has been running fine up until Christmas, but after returning back from my parents, I went to start it up and the battery was flat.

I jumped it off my girlfriends Corrado and got it started fine, left it on idle for an hour or so and then the next day took it for a long drive. Last monday and tuesday my girlfriend took it to work and said it was all working fine. So I went to start it up on Saturday and the starter motor was turning but it wasn't firing, I also noticed the lights were dimming when I went to start the car. The next day I swapped the battery from the Corrado and put it into the Golf. Even with the new battery it still had the same problem, however after 5 attempts I managed to get it to start, although it is running really roughly and misfiring. I also tried to turn on the radio (to check whether it was an electrical problem) and the radio wasn't working either (usually works fine).

Since I know the battery in the Corrado is in good working order, I can rule that one out. So I am guessing something is up with the alternator and the car isn't getting enough power to fire properly. Both the rotor arm and dizzy cap were replaced fairly recently and I can't see any arching from the HT leads either. Is there anything else I should check, or should a new alternator do the trick?

Cheers,

Dave.
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Offline Mew

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Re: Alternator on the way out?
« Reply #1 on: 12 January 2009, 10:16 »
First thing i'd do is clean up the earth points, mainly because it's free!
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Offline rubjonny

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Re: Alternator on the way out?
« Reply #2 on: 12 January 2009, 11:09 »
does the battery light come on with the ignition then go out when car is running?
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Offline cox

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Re: Alternator on the way out?
« Reply #3 on: 12 January 2009, 11:26 »
Quote from: rubjonny on 12 January 2009, 11:09
does the battery light come on with the ignition then go out when car is running?

Just tried it and yes it does...
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Offline rubjonny

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Re: Alternator on the way out?
« Reply #4 on: 12 January 2009, 11:33 »
ok that means the alt is charging at least a bit, need to get a multimeter on there and check the voltages.  Could also be the battery is being drained by something, or its just dead!
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Offline cox

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Re: Alternator on the way out?
« Reply #5 on: 12 January 2009, 11:52 »
Quote from: rubjonny on 12 January 2009, 11:33
ok that means the alt is charging at least a bit, need to get a multimeter on there and check the voltages.  Could also be the battery is being drained by something, or its just dead!

The battery definitely isn't dead, I took the one I thought was dodgy out and put in a pretty new one in from a corrado. It has one of those onboard testers that lets you know when it is running low and it says it is ok.

Any suggestions as to what could be draining the battery?

Thanks,

Dave.
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Offline rubjonny

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Re: Alternator on the way out?
« Reply #6 on: 12 January 2009, 14:25 »
quick test is to unplug the battery -ve and leave it for the same period o time. if its still flat its the battery, if its not then start looking at your electrics for a volt drain.  badly wired stereo, dodgy alarm and bootlight left on are main starting points :)
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Offline cox

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Re: Alternator on the way out?
« Reply #7 on: 16 January 2009, 13:14 »
Just a quick follow up since this problem has now been sorted (thanks to my local mechanic). In the end it was that the alternator that needed tightening. He told me that you shouldn't be able to turn the alternator blades around with your hands, which you could with mine. So although the alternator was working, it just wasn't generating enough power to run the car smoothly. Along with that he also checked and cleaned up a few parts like the connector to the coil which leads to the dizzy cap and gave the spark shield within the dizzy cap a polish up too.

Runs fine now. Fixed just in time for its MOT today, so hopefully there will be no other surprises in store! :)

Cheers for all your help/suggestions though. Much appreciated!

Dave.
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