Kev T Posted March 18, 2007 Share Posted March 18, 2007 Gents; I have a 1982 GLF 1.8litre. Fully stock with 120 k kms. I noticed that the voltage guage reads low (9 volts?) when I idle then jumps back up to 12 when I am moving. The headlights dim at a red light then go bright when I rev. I also notice that turning on the rear window defrost drops the voltage to around 8 volts. I replaced the alternator today however it did not change a thing. Is there a voltage regulator or something else that could be going bad? Any thoughts? Cheers Kev Quote Link to comment Share on other sites More sharing options...
naru Posted March 18, 2007 Share Posted March 18, 2007 The regulator is inside the alt. on your 82.Any problems other than the low voltage readings? The headlight dimming thing is normal on these cars.Check your dash gauge against another meter.The dash gauges are notoriously inaccurate. Quote Link to comment Share on other sites More sharing options...
Kev T Posted March 18, 2007 Author Share Posted March 18, 2007 No other problems except that the battery does not take a charge. It is only a few cranks from dead and when I hook up the charger it says defective battery. I was assuming that the bad alt was killing the battery. Could this just be a battery problem? Quote Link to comment Share on other sites More sharing options...
DaveT Posted March 18, 2007 Share Posted March 18, 2007 Could this just be a battery problem? On my EA82s, I have noticed that the voltage will drop when the car goes to idle with lights and other loads on when the battery is near end of life. Quote Link to comment Share on other sites More sharing options...
crazy D Posted March 18, 2007 Share Posted March 18, 2007 ive been having the same problem except my alt is rebuilt and my battery is like a year old......what is wrong? i want to run more lights but it wont happen until i fix this Quote Link to comment Share on other sites More sharing options...
naru Posted March 18, 2007 Share Posted March 18, 2007 No other problems except that the battery does not take a charge. It is only a few cranks from dead and when I hook up the charger it says defective battery. I was assuming that the bad alt was killing the battery. Could this just be a battery problem? Yes,Sounds like a sulphated battery,but,you should confirm your cars ability to charge before buying a new one. Quote Link to comment Share on other sites More sharing options...
Skip Posted March 18, 2007 Share Posted March 18, 2007 Sounds to me like half the diode bridge is out in the alt rectifier They do this quite often. Replace the diodes or easier path replace the alt. I include this mearly as a qualifier as I have done a few of these. Quote Link to comment Share on other sites More sharing options...
Bucky92 Posted March 18, 2007 Share Posted March 18, 2007 My XT6 does the same thing..dimming and volts drop..but never that low anymore..only to about 11-12 volts ( had alt tested and puts out 15.5 volts at anything over 1000rpms) I just had my alt rebuilt and put a new belt on .. I might have a spare alt for you EA81 if you need it or want to try it..dont have any EA81s anymore so if you want to try it cover shipping and its yours..just would have to make sure I still have one..I have about 3 EA82s Quote Link to comment Share on other sites More sharing options...
Frank B Posted March 18, 2007 Share Posted March 18, 2007 Check the voltage with a multimeter, voltmeter. Just test on the battery terminals at idle, then open the throttle with your hand and see if it goes up to 14.4 or so. 12 volts isn't enough. 13-14.4v is what you need. Every Subaru I've had has dropped at idle. But it sure wouldn't hurt at all to replace the battery and the alternator. When a battery goes through a few discharge cycles, it's usually done for. Quote Link to comment Share on other sites More sharing options...
daeron Posted March 19, 2007 Share Posted March 19, 2007 I include this mearly as a qualifier as I have done a few of these. The full setup, complete with the workshop chair made from the seat out of a GL-10!!! (GOD I love those seats!) A man after my own heart. are the diodes inside the alternator with an externally regulated alternator? somewhere along the line during my education I got the idea that the diodes were a part of the voltage regulator, but now that I think on it that doesn't seem right.. but I don't know, so now I have gotten confused. Another very real possibility lies in the wiring of the vehicle; if the charging wire on your alternator is in poor condition, then the resistance kills off your current at low RPMs.. Do a search on alternator swaps to learn more about how to replace your charging wire. It usually gets done when someone swaps to a higher amperage alternator (like out of an XT6, or a maxima at 90 aps compared to the ea82s 60.. ea81s may have had even less...) Personally, I wonder how much improvement people see from the alternator swap, and how much improvement people see from replacing the wires... Not that higher amperage alternators aren't needed for lots of lights, etc... Its just that no one ever thinks to do something like this before changing to a new alt. BTW, Skip.. those ventilated hitachi alternators up onthe left side of your shelf there.. are those the XT6 units? Quote Link to comment Share on other sites More sharing options...
Cougar Posted March 19, 2007 Share Posted March 19, 2007 Along with the others I too would suggest you get the battery and the alternator checked out for a problem. Like Skip mentioned, it does sound like some of the diodes are bad in the alternator. Along with that make sure the battery connections have been cleaned using a battery brush. There may also be a problem with the accessory power wire that feeds power to the fuse panel. This is the smaller lead tied to the positive terminal. The voltage gauge in the dash will normally read about 1 volt lower than the battery voltage due to wiring losses. If the voltage drop is more than that then you need to check the wiring between the battery and the fuse panel for a problem. The fusible links connections are the first spot to check. Quote Link to comment Share on other sites More sharing options...
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