Hi all,
I think I may have an alternator issue, when the car is running it sits nicely around 800rpm, if I put the lights on you notice a dip, maybe 750rpm but it's still fine, as soon as you put the windscreen wipers or fans on, then the rpm drops and the car stutters/cuts out. It doesn't have a radio at the moment but I guess with this it will be even worse!!!
I have replaced the battery, but I guess the next step is the alternator?
I'm thinking there is not enough charge getting to the battery for it to keep up running the car when under strain from other requirements?
Any thoughts would be great, thanks
Ryan
Potential alternator issue
Forum rules
Hints, tips and guides for repair and modification - the FAQ section on the main website is worth checking first for information relating to common faults and technical help. Useful posts and guides will be added to the FAQ http://www.sciroccoregister.co.uk/scirocco-faq
Hints, tips and guides for repair and modification - the FAQ section on the main website is worth checking first for information relating to common faults and technical help. Useful posts and guides will be added to the FAQ http://www.sciroccoregister.co.uk/scirocco-faq
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Nate
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Re: Potential alternator issue
Time to grab the multi meter and do some testing!
With the engine warm and running, check battery voltage, check for voltage drop on the earth and on the large +ve. Also worth measuring AC volts at the battery to see what the health of the alternators rectifier is like
With the engine warm and running, check battery voltage, check for voltage drop on the earth and on the large +ve. Also worth measuring AC volts at the battery to see what the health of the alternators rectifier is like
Re: Potential alternator issue
Battery seems to sit around 13.3v it was like this with the old battery and replaced with a brand new one with higher CCV and it still sits at 13.3v, never check an alternator myself so not sure of the procedure...
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mark1gls
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Re: Potential alternator issue
800 rpm is a little low for a tick over try increasing it to 900 rpm.
Get a multimeter and set it to Volts and place it across the earth and live on the battery, with the engine running you should get around 14v.
Also check the regulator on the alternator as the bushes wear out, the regulator is held on with 2 screws and looks like this.
http://www.ebay.co.uk/itm/VW-GOLF-MARK- ... 62T5smTziA
My worn out regulator compared to a new one.
There is also 2 connections on the regulator to the alternator give them a clean so they have a good connection.
Get a multimeter and set it to Volts and place it across the earth and live on the battery, with the engine running you should get around 14v.
Also check the regulator on the alternator as the bushes wear out, the regulator is held on with 2 screws and looks like this.
http://www.ebay.co.uk/itm/VW-GOLF-MARK- ... 62T5smTziA
My worn out regulator compared to a new one.
There is also 2 connections on the regulator to the alternator give them a clean so they have a good connection.
Mk1 78 Scirocco GLS 1.6 FR, weekend toy.
Mk1 88 Golf GTi cabriolet 1.8 DX. Daily drive.
Membership No. 323
Mk1 88 Golf GTi cabriolet 1.8 DX. Daily drive.
Membership No. 323
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unknownmale
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- Location: London
Re: Potential alternator issue
Do you have a picture of the alternator in situ.
13v suggests it's working, but possibly underpowered? Depending on the model it could be a faulty voltage regulator, possibly poor contact with the brushes, worn brushes. Could even be a slipping belt, corroded connections creating resistance.
I would first test voltage at the post on the alternator, and ground (Casing or bracket) This would rule out any poor connections. If the output is correct then you'll know it an issue with ether the ground from the alternator to the block (Clean with a file) or the positive connection to the battery. If the output is too low at the alternator then you can focus your attention there. Sounds obvious, but check it's the correct alternator, a previous owner could have fitted something else in there which could have the wrong pulley size/ wrong amperage rating etc.
If everything checks out there I would look at the regulator as pictured above, you can see the brushes are very worn which could cause poor contact with the commutator, or of course the regulator itself could be at fault.
That should get you closer to the issue
13v suggests it's working, but possibly underpowered? Depending on the model it could be a faulty voltage regulator, possibly poor contact with the brushes, worn brushes. Could even be a slipping belt, corroded connections creating resistance.
I would first test voltage at the post on the alternator, and ground (Casing or bracket) This would rule out any poor connections. If the output is correct then you'll know it an issue with ether the ground from the alternator to the block (Clean with a file) or the positive connection to the battery. If the output is too low at the alternator then you can focus your attention there. Sounds obvious, but check it's the correct alternator, a previous owner could have fitted something else in there which could have the wrong pulley size/ wrong amperage rating etc.
If everything checks out there I would look at the regulator as pictured above, you can see the brushes are very worn which could cause poor contact with the commutator, or of course the regulator itself could be at fault.
That should get you closer to the issue
- David
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Nate
- Posts: 4045
- Joined: Thu Apr 02, 2009 10:37 pm
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- Location: Cirencester / Swindon
Re: Potential alternator issue
I will do a write up with pics at the weekend of how to test alternator. I'm away until Saturday morning though