rbastedo Posted April 5, 2014 Report Share Posted April 5, 2014 O'Reilly remanufactured 65 amp alternators. I have the two wire connector, the hot +12V lead and the wire that goes from a spade lug to the distributer. My battery was going dead, but I just put this battery in brand new a week ago. The problem wasn't happening before getting the new battery, the old one turned 7 years old so I replaced it. I put my meter between the battery negative post and ground (disconnected first) to read current draw. Read 2.5 Amps with everything turned off. Pulled fuses one by one, no change. Pulled the two wire connector from the back of the alternator, dropped to zero Amps draw. Sounds like blown diodes in the alternator. What can cause it, what can I do about it? Quote Link to comment
datzenmike Posted April 5, 2014 Report Share Posted April 5, 2014 Often the reman alternators are crap right out of the box. Keep returning them until you get a good one. Quote Link to comment
Dguy210 Posted April 5, 2014 Report Share Posted April 5, 2014 Often the reman alternators are crap right out of the box. Keep returning them until you get a good one. Yes, this so much! I'm on my third O'Reilly alternator in the last 3 years. The lifetime warranty takes the pain out of it but it still sucks having to screw around. They will test them in store for you, they can still test good but take a listen as they test and play with the alt to look for bearing slop. I had them run through a batch until I got 2 good ones, one to put on the car and a good spare. Quote Link to comment
rbastedo Posted April 5, 2014 Author Report Share Posted April 5, 2014 That has been my experience too, I just got this one in January it's lasted the least of any I have gotten from them. I started thinking I'm doing something wrong. It is charging at 14.7 and that seems a bit on the high side and like I said drawing 2.5 amps whenever the connector is plugged in. Could replacing the battery blow out the diode? I assume that is what's happened here why it's drawing 2.5 amps. Quote Link to comment
datzenmike Posted April 5, 2014 Report Share Posted April 5, 2014 Can't see how. Batteries are about 12.3 volts fully charged. Alternators make 14 to 15 volts output. They are simply a crappy Asian rebuild. A new Nissan alternator is close to $300, no wonder they last the life of the vehicle and even then probably only need new brushes. Quote Link to comment
ggzilla Posted April 5, 2014 Report Share Posted April 5, 2014 14.7 volts is right in the middle of the spec. Here is the chart for the A15 alternator Quote Link to comment
ggzilla Posted April 5, 2014 Report Share Posted April 5, 2014 If the diodes blow out, it won't draw current. If they short out it might. Most typically one diode will blow, which results in reduction of 1/3 the output. It will start making a slight electrical whine. Quote Link to comment
ggzilla Posted April 5, 2014 Report Share Posted April 5, 2014 O'reillys site today list only the "Ultima" brand remanufactured alternator. So probably a different brand than you got before. NAPA has a Bosch rebuild for $78. They have been quality rebuilds in the past. Quote Link to comment
ggzilla Posted April 5, 2014 Report Share Posted April 5, 2014 I have the two wire connector, the hot +12V lead and the wire that goes from a spade lug to the distributer. The E terminal should go to Earth/Ground and be bolted (not a spade terminal, which corrode over time). The distributor body is a ground, but not a reliable one. I would ground it to the timing cover bolt like Nissan did. Quote Link to comment
banzai510(hainz) Posted April 5, 2014 Report Share Posted April 5, 2014 buy this or soemthing similar to this that plugs in the cig lighter so You can catch it before you stuck out there somethere. Even Walmart has a cheap plug in digatal volt meter that goes in the cig lighter thay WORK trust them. http://www.equus.com/Product/3721/Battery-Monitor Quote Link to comment
rbastedo Posted April 6, 2014 Author Report Share Posted April 6, 2014 Strange stuff.I took the alternator in and they tested it ans said it was bad.I eventually got a new one and brought it home and installed it.Started the car and it ran great and the charging was at 14.3 VDC.I turned it off, pulled the negative cable from the batery and measured draw.2.5 AmpsThrew up my hands and gave up.Pulled a toggle switch and some wire and ran it to the alternator and installed a bypass.The "top" wire had no impact on disconnection.The bottom wire (of the two wire plug) had the effect of making the current draw zero when disconnecting.I put my toggle switch on this wire.The wierd part:When the toggle is off the car starts fine and the charging of the battery is at 14.3VDC.The current draw is zero when the car is turned off. The second wire of the two wire plug draws 2.5 amps with the toggle on. The second wire is not needed? Quote Link to comment
ggzilla Posted April 6, 2014 Report Share Posted April 6, 2014 L could be the top wire S could be the top wire ... depending on make of alternator and orientation L wire is always at the head of the Tee connector Quote Link to comment
datzenmike Posted April 6, 2014 Report Share Posted April 6, 2014 What exactly is this in, an MG??? Is it an external regulated set up? Maybe you have an internal regulated alternator? Maybe the L and S wires are swapped on the MG side? Quote Link to comment
rbastedo Posted April 6, 2014 Author Report Share Posted April 6, 2014 MG Midget It has functioned pretty much correctly for the past 7 years, not sure what has changed. The way I understand it is: L goes to the charging lamp, red light on dash Start car, lamp goes on, excites circuit in alternator to switch charging on, lamp goes out What is the function of S? Quote Link to comment
datzenmike Posted April 6, 2014 Report Share Posted April 6, 2014 Maybe you accidentally were switched from external to internal alts.??? Or the other way round. '78 and up were internal on all Nissans. I don't know what set up you have on an MG... probably an external voltage regulator? Quote Link to comment
MikeRL411 Posted April 6, 2014 Report Share Posted April 6, 2014 Maybe you accidentally were switched from external to internal alts.??? Or the other way round. '78 and up were internal on all Nissans. I don't know what set up you have on an MG... probably an external voltage regulator? If you still have the Lucas electrical system in your Midget/Sprite, you are in for a really frustrating ride. Good luck. Quote Link to comment
izzo Posted April 6, 2014 Report Share Posted April 6, 2014 I can vouch for the cheap alternators, too. While it could possibly be something else. I have never had any luck with orielly or autozone alternators. I spend the extra few bucks at NAPA auto parts and use theirs. Over priced, probably. But I install and forget about it. Hell they probably in 5 cars while in my hands with the way I go thru cars :rofl: Check the part numbers between napa and autozone and who the mfr is. often if the same mfr i can get them to lower the price, even tho they use higher quality parts for the reman at napa. You could take it to a reputable shop and have it rebuilt right on the spot to your specs with higher grade parts. Quote Link to comment
rbastedo Posted April 6, 2014 Author Report Share Posted April 6, 2014 The ignition switch is for the MG, I have replaced a lot of the other parts. It's a 78, they came with internal regulator alternators. O'reillys wanted to charge me $87 for this alternator, I told them nope - warranty replacement. That's when he took the old one back to test it, came up and said it didn't pass and handed me the new one. I doubt he knew what he was doing and finally just opted to believe the customer since this new one acts just the same as the old one did. Anyway, from the diagram above it looks like the S wire can be jumpered to B. Then I only have to be concerned with the L circuit. I'll make sure that goes to the lamp and the lamp comes on when I turn the ignition switch on then the lamp should go out once the alternator gets "excited". If the lamp does not go off then that means the alternator or the ignition is feeding power to the lamp - easy process of elimination. Maybe no easy solution, but it should be easy to figure out which one is feeding power to the lamp. Quote Link to comment
ggzilla Posted April 6, 2014 Report Share Posted April 6, 2014 L is lamp. S is sense. It doesn't work like old alternators. L is an on/off switch for the lamp. If the lamp does not go off then that means the alternator or the ignition is feeding power to the lampExcept the light is already connected to power via the car's instrument panel harness. Quote Link to comment
thisismatt Posted April 6, 2014 Report Share Posted April 6, 2014 The S is your voltage sense circuit. It's the voltage the alt reads to determine output. Connecting it directly to the alt positive output or even the battery can give you undesirably low voltage output. It's better to have it connected farther away where it can detect voltage drop and increase output accordingly. Quote Link to comment
ggzilla Posted April 6, 2014 Report Share Posted April 6, 2014 Wrong. Datsun connected it directly to the fusible link. Check the factory service manual. Quote Link to comment
rbastedo Posted April 6, 2014 Author Report Share Posted April 6, 2014 The S is your voltage sense circuit. It's the voltage the alt reads to determine output. Connecting it directly to the alt positive output or even the battery can give you undesirably low voltage output. It's better to have it connected farther away where it can detect voltage drop and increase output accordingly. That makes 'sense' to me. I am about to the place where I get a little free time to go out and look at this again, so I will check it all out and come back with what I find. Quote Link to comment
rbastedo Posted April 6, 2014 Author Report Share Posted April 6, 2014 Wrong. Datsun connected it directly to the fusible link. Check the factory service manual. All right, well I don't seem to have a fusible link so what's a suitable different place to connect this? Quote Link to comment
ggzilla Posted April 6, 2014 Report Share Posted April 6, 2014 Direct to the battery POS terminal. See the wiring schematic posted earlier. Quote Link to comment
thisismatt Posted April 6, 2014 Report Share Posted April 6, 2014 Wrong. Datsun connected it directly to the fusible link. Check the factory service manual. What's wrong? Don't get me started on all the "wrong" electrical that Nissan did at the factory. Edit: Not to say that I don't think connecting to the battery positive isn't fine, it is. I was more talking about jumping straight to the alt output, which people do when trying to create a one wire alt... Quote Link to comment
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