Alternator Packed Up?

[SteG40]

My car won't start at the moment. It started doing it at York raceway on monday. I'm thinking it's the alternator because it's the only thing i've not replaced everything else is fairly new. I've checked the battery with a multimeter and it shows:
11.6v with engine off
12.3v engine on with all lights, radio etc on.

Now I know these are too low but even with those readings should it not at least start or turnover. Should I just stick a one on or is there anything else worth checking?

[Alexiskayak_7]

[quote pid=3575 author=SteG40 date=1219782278]My car won't start at the moment. It started doing it at York raceway on monday. I'm thinking it's the alternator because it's the only thing i've not replaced everything else is fairly new. I've checked the battery with a multimeter and it shows:
11.6v with engine off
12.3v engine on with all lights, radio etc on.

Now I know these are too low but even with those readings should it not at least start or turnover. Should I just stick a one on or is there anything else worth checking?[/quote]


If the alternator isn't working properly while the engine is on and you having the lights, interior fan, radio etc on, the Volts of the battery should start falling slowly (the alternator isn't charging the battery). I think that a sensor isn't working properly...

[G-spot]

Check voltage at each end of +ve cable that runs directly to starter motor, I found that mine had poor continuity at the battertry terminal end, which I solved by re-soldering the clamp onto the +ve cable.

[jonboy]

check the voltage whilst cranking the car (at the battery) if it drops to around 6v the battery is flat.
start the car, jump it if you have to! now read the voltage at ther terminals of the alternator, you should get at least 13v, if not it is goosed. if it does read 13 then i would say your battery has failed.
when you remove the alternator, check the condition of the brushes (there is a small plastic part, held by 2 screws, this is the voltage regulator/ brush pack.  these can be replace if they are worn) also make sure the small wire connected to the capacitor on the side has a good connection, on my gt the wire had corroded to nothing, which caused the alternator to fail.

[SteG40]

Thanks for your help guys, checked it tonight and it's the alternator. it's only putting out 7 volts, time to get a new one.

[jonboy]

[quote pid=3606 author=SteG40 date=1219872028]Thanks for your help guys, checked it tonight and it's the alternator. it's only putting out 7 volts, time to get a new one.[/quote]


it might just need new brushes, easy job to do and will save you loads of money

[giorgio]

[quote pid=3606 author=SteG40 date=1219872028]Thanks for your help guys, checked it tonight and it's the alternator. it's only putting out 7 volts, time to get a new one.[/quote]

there was a nearly new one knocking about on club polo. Failing that see this thread - http://www.polog40.co.uk/forum/index.php?topic=341&page=1

[lance]

my alternater bottom bolt worked its way free a long time ago and blew to pieces lol got annother G40 one brandnew for 55 pound i think.

[DKnight]

yeah we have a place round here that refurbed it for £30, worked fine

[vwmk3jon]

Dan, any details of the place that refurbed the alternator? Think mine needs doing as i've got the battery light showing again!

[scotsjohn]

[quote pid=3606 author=SteG40 date=1219872028]Thanks for your help guys, checked it tonight and it's the alternator. it's only putting out 7 volts, time to get a new one.

it might just need new brushes, easy job to do and will save you loads of money
[/quote]

Bang on jonboy. I've already suggested this. It's about five years since I did one and I really can't remember the cost so it can't have hurt that much. ( Saying that I can't remember what I had for dinner last night). A clean up of the commutator/slip ring and new brushes makes your grimey old alternator a much happier piec of kit.

[scotsjohn]

Just an update on poor alternator performance. Had the charger off for service but checked voltage readings beforehand. 13.3 volts on idle and 13.5 at 2000rpm. Switching on everything it nosedives to 12.8 volts at 2k.

With the charger away, I treated the alternator to a new brush pack as suggested by jonboy. With everything back in place, I'm seeing 13.8 volts on idle,14volts at 2000 and with everything switched on, 13.3 at idle and 13.7 at 2000 revs. All for £13.

Your alternator's a pretty tough cookie:it either goes or it doesn't. If it fails it's a fried winding or a blown diode and you'll get that nice wee red light to tell you. Poor output is almost always poor connections/brushes. New is nice but £13 is nice too sometimes.