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Car Forum / Subaru Cars / July 2008Alternator bad? Voltage regulator maybe?
Car wouldn't start (an old '92 Subaru Legacy L wagon). Battery is about 3 years old and the car started a week ago. However, today it just cranked like one turn and died. I can hear the relay click as I turn the key but the engine doesn't budge. I also noticed the electric seat belt moved slowly. I popped the hood, jumped started from my other car, and with a voltmeter measured across the battery. It measured 12.5V. As I recall, each cell in a new battery should be 2.2 volts and there are 6 cells so a new battery should measure 13.2 volts, so 12.5V isn't bad for a middle-aged battery. However, I expected the voltage to be higher while the car was running due to the output from the alternator. The voltage also did not fluctuate when I revved the engine. It dropped a volt when I turned on the headlights. So it looks like the alternator is bad. While 16 years old, mileage is only 135K so, on average, the 2 alternators have lasted only about 67K which seems a bit short-lived (actually the first one probably lasted 105K and the 2nd died after another 30K). I had to replace this alternator about 4 years ago. The prior run burned up. Its bearing went bad and it heated up so you could smell the varnish on the windings within a few blocks of driving from cold. It was a rebuilt and is now out of warranty. I got it for around $80. The salvage place doesn't have another alternator (except for a retail-priced new one). I can get one for $118 at PepBoys with a lifetime warranty; however, I'm wondering if just the voltage regulator is shot. I can't see what the module is on the outside so maybe the regulator is inside. If inside, I'm not dismantling it to replace that module. I suspect if it is inside that it'll be riveted and positioned where it won't be easy to get out to replace it, assuming that just the regulator can be purchased and is much cheaper. If the voltage doesn't get above what the battery alone will provide, is it even a voltage regulator problem? I can't find my battery charger so I'll call a buddy to drop by with his. I need to charge the battery so I can get to PepBoys to have them do an alternator test and have enough juice in the battery to start it again to get the old Subie back home. What should be the voltage across the battery while the car is running and with a working alternator? I thought it was 14.4V. It would have to be higher than the 13.2V for a new battery. Is the voltage regulator inside or outside? How trustworthy are these parts shop alternator testers? Suggestions on how to go cheap on the alternator replacement? The 1-year salvaged rebuilt alternator lasted 4 years. Considering it was a third the price, another 4 years is just fine with me. This alternator has an IR. Problem probably is the alternator has lost diode. Not worth tinkering with if you haven't rebuilt a few. You ca use a much newer alternator if willing to change the wiring plug. Thinking 1994 was the year the plug changed. - Message posted using http://www.talkaboutautos.com/group/alt.autos.subaru More information at http://www.talkaboutautos.com/faq.htm > This alternator has an IR. Sorry, but my primary career has been in computers. IR, to me, means InfraRed, as in the light spectrum used by communication transmitters/receivers. Maybe IR means Internal Regulator? I just looked again at the alternator in my car and see nothing that is accessible from the outside to let me swap out a regulator module. I couldn't even find a tag that listed the amp rating. Any idea how many amps the replacement alternator should supply? I think it is 70 or maybe 80 amps. This car does have air conditioning (the compressor is still in place but the system sprung a leak after a recharge and hasn't worked in over 10 years - I'd like to remove the compressor to remove any drag, if there was any since it is never turned on, but don't see how to put a pulley there for the belt). Of the few places that mentioned a rating, I usually see 70A units although 50A and 90A were also mentioned. > Problem probably is the alternator has lost a > diode. Not worth tinkering with if you haven't rebuilt a few. You can > use a much newer alternator if willing to change the wiring plug. > Thinking 1994 was the year the plug changed. Never rebuilt an alternator. My guess, based on the assumption that bad luck is likely, is that I would open it up and find I had to dismantle everything to get at a module that is riveted behind everything else. I found a diagram of the alternator at http://tinyurl.com/6rx7so. Yep, the voltage regulator is inside (on item #2). Looks like it might be possible to open it up to replace just the "plate" holding the regulator; however, the prices that I've seen for the regulator alone are higher than the entire rebuilt alternator. Splicing in a new plug wouldn't be a problem for me. I'm very handy with soldering and heatshrink tubing to make a solid inline splice. The problem would be getting the plug. I don't know that a new alternator would include a matching plug. The rebuild that I bought last time didn't include one. If I don't get one spec'ed for my car, I'm also guessing the mounting plates and holes won't line up. After checking some other maintenance receipts to figure out what the mileage might've been at the time I replaced the alternator, the 2nd alternator now in the car (which was the rebuilt replacement from the salvage shop with 1-year warranty) only lasted maybe all of 20K miles which seems damn short. The 72-month battery is only 16 months old. Is it possible a weak or defective battery would result in the voltage readings that I saw (12.5V across the battery terminals with the car running)? It'd be easier to dump in a new battery than take off the fan belts to remove the alternator and have to do it in reverse again. Even if the battery were defective, I still expected the voltage to rise when I revved the engine. Apparently to have the alternator tested at the parts store means having to remove it from the car; i.e., they can't test it /in situ/. I have the following choices (for cheapest prices found so far), all of which are rebuilds: - ProStart brand: $118.99 (PepBoys; also at Advance Auto but I can't get a price online and too late to call right now). - Autolite (Pro-Tech) brand: $129.99 (Advance Auto or Checker Auto Parts since both use PartsAmerica.com). - O'Reilly Auto Parts (no brand identified other than "Ultima"): $119. All have lifetime warranties. The Autolite unit includes a roadside assistance perk (with a $60 max reimbursement). They didn't mention the amperage rating so I'll have to check that tomorrow. Any experience in which brand or store you like best for an alternator? >> This alternator has an IR. > [quoted text clipped - 62 lines] > amperage rating so I'll have to check that tomorrow. Any experience in > which brand or store you like best for an alternator? Hi, I'd rather think I in this case stand for integrated or imbedded. If alternator is really proven bad, it can be rebuilt if you want to. Or hen you bring bad one it's worh a few bucks in exhcange. The only difficult part opening up an alternator is removing the pulley Only thing I found that always works is an impact gun. Once the pulley i off just remove those long bolts running through the case and everythin falls apart. Just mentioning this if you decide to open it to inspect th insides. When a diode fails the battery "back drains" through th alternator which I think is your problem. Or at least part of th problem. There are companies out there that sell new connectors but th easy way to get the newer connector is to just cut one from a newe wrecking yard car. You don't have a 90A alternator now. Use to know th amperage output but now guessing in the 75A range. I have never had goo results with using rebuilds, or at least the kind sold at auto part stores. Quality over the years has been very poor. - Message posted using http://www.talkaboutautos.com/group/alt.autos.subaru More information at http://www.talkaboutautos.com/faq.htm > The only difficult part opening up an alternator is removing the pulley. > Only thing I found that always works is an impact gun. Once the pulley is [quoted text clipped - 8 lines] > results with using rebuilds, or at least the kind sold at auto parts > stores. Quality over the years has been very poor. While I might attempt dismantling the alternator (although I don't have an impact wrench), the deterring factor now is the high price for the voltage regulator replacement part. It costs more than the rebuilt alternator, and the same price as a new alternator. No point in buying just the part when I can get the entire unit for the same or cheaper price. With a lifetime warranty (limited to the original car it was installed in) and the much reduced price of a rebuild and the ease of replacing the alternator (the belt and a couple bolts), I'll probably go with the rebuild. > Car wouldn't start (an old '92 Subaru Legacy L wagon). Battery is about > 3 years old and the car started a week ago. However, today it just [quoted text clipped - 46 lines] > 1-year salvaged rebuilt alternator lasted 4 years. Considering it was a > third the price, another 4 years is just fine with me. Hi, Sounds like your battery is drained by some unknown load or it is bad. Probably one cell gone bad. If you can't test battery, try another one then yo can decide. When charging the voltage should be ~14V. Is the battery warm to touch? >> Car wouldn't start (an old '92 Subaru Legacy L wagon). Battery is about >> 3 years old and the car started a week ago. However, today it just [quoted text clipped - 51 lines] > then yo can decide. When charging the voltage should be ~14V. Is the > battery warm to touch? No warmth to the battery (when unused or with the car running). Even if the battery was bad, wouldn't the voltage across it go up due to output from the alternator (when the car is running)? >>> Car wouldn't start (an old '92 Subaru Legacy L wagon). Battery is about >>> 3 years old and the car started a week ago. However, today it just [quoted text clipped - 56 lines] > Even if the battery was bad, wouldn't the voltage across it go up due to > output from the alternator (when the car is running)? Hi, No. because bad battery will load down the alternator like a partial short. It happens when one electrodes inside battery cell shorts out. Generally batteries cause more trouble than alternaotr/VG. Even brand new battery can fail. One factor of better battery is mechanical rigidity. >>>> Car wouldn't start (an old '92 Subaru Legacy L wagon). Battery is about >>>> 3 years old and the car started a week ago. However, today it just [quoted text clipped - 61 lines] > Generally batteries cause more trouble than alternaotr/VG. Even brand > new battery can fail. One factor of better battery is mechanical rigidity. Took the battery to the car shop. The first handheld tester said Good (but a recharge was needed but I already knew that). That included a check for the short condition. Then they shoved in the big tester that first charges the battery for 30 minutes (ho hum, wander the store) and it tested okay. They also plug in the cold-cranking amp rating to check the battery can supply that load (although 85F outside and 70F in the store isn't really "cold"). Couldn't find my trickle charger at home so picked up a 3-stage one at a different store where it was cheaper and am charging the battery tonight. That's because this car shop says they can test the alternator while in-place but it requires the car can startup on its own while testing. They have an emergency jump kit to let me start and drive back home but they need the car to be able to start itself using the battery and alternator without being jumped. So tomorrow I find out more. May want to read this. Mitsubishi, not a Subaru, but essentially the sam design. http://www.stealth316.com/2-alt-rebuild.ht - Message posted using http://www.talkaboutautos.com/group/alt.autos.subaru More information at http://www.talkaboutautos.com/faq.htm Ok, just my 2 cents. Before killing the alternator, a battery with a dead cell can prevent the voltage from the alternator from going to normal charge levels when measured at the battery. Clean the alternator connections, make sure that the Alt S fuse connections are clean, make sure that the connector that plugs into the alternator is clean. Make sure that the fusible link and main fuses are clean. Mind the ground connections and battery terminals as well. Also, make sure that the v-belt is in good shape and that i has the proper tension. I have seen them slipping with no squeal. Charge the battery and measure the voltage at the battery when cranking. It should be more than 9 volts. When the motor is running, a properly charged battery should see 14.2 to 14.8 volts in a properly regulated system (those that allow batteries to last for 7 years, ;) ) Good luck! > Car wouldn't start (an old '92 Subaru Legacy L wagon). Battery is about > 3 years old and the car started a week ago. However, today it just [quoted text clipped - 46 lines] > 1-year salvaged rebuilt alternator lasted 4 years. Considering it was a > third the price, another 4 years is just fine with me. Well. what was the problem - Message posted using http://www.talkaboutautos.com/group/alt.autos.subaru More information at http://www.talkaboutautos.com/faq.htm > Well. what was the problem? Been busy replacing air conditioners, rebuilding windows, and cleaning the yard of debris and hauling it away. Just haven't gotten to working on the car yet this week beyond getting the battery charged. My buddy is coming over (maybe) this Saturday or Sunday to help with more debris (which reminds me that I have to get busy with the chainsaw) and getting rid of a removed water heater. Afterward, he'll accompany me when testing the alternator just in case I need a ride back or a battery jump (although the store says they have an emergency boost kit). While some car shops say the alternator must be removed, this one says they can test with the alternator in place but the battery must be in the car and capable of starting the car itself (no boost, no jump). So, for now, it looks like this job waits until this next weekend. Hmm, come to think of it, I should put the charged battery back into the car and connect it up. If there is a leak in the wiring or other component (or even through the alternator) then I might see this by next weekend (although the battery might still be good enough to start the car so I'm not sure this test will reveal anything). > Hmm, come to think of it, I should put the charged battery back into the > car and connect it up. If there is a leak in the wiring or other > component (or even through the alternator) then I might see this by next > weekend (although the battery might still be good enough to start the > car so I'm not sure this test will reveal anything). Before you reconnect the battery, put an ammeter in series with the positive cable. You will see any current draw. If you get a current draw pull the plug on the alternator and see if goes away. >> Hmm, come to think of it, I should put the charged battery back into the >> car and connect it up. If there is a leak in the wiring or other [quoted text clipped - 5 lines] > positive cable. You will see any current draw. If you get a current draw > pull the plug on the alternator and see if goes away. Good idea. I've got an old ammeter (Amp Probe) that I inherited from dad. >> Hmm, come to think of it, I should put the charged battery back into the >> car and connect it up. If there is a leak in the wiring or other [quoted text clipped - 5 lines] > positive cable. You will see any current draw. If you get a current draw > pull the plug on the alternator and see if goes away. Did as you mentioned. The old ammeter didn't budge when I put it across the "+" on the battery to the positive cable (with the negative cable already connected to the "-" battery post), even on the 6A range. That seemed weird since I know the radio is still hooked up and has a clock in it. So I got out my DVM which has a 2A scale and it showed 0.438A, or a little under half an amp. Odd part was that it showed -0.438A (with red probe to cable and black probe on "+" battery post), as though current was running to the battery instead of out. In any case, there is a little bit less than an ampere showing on the DVM from the battery. I left the battery disconnected until it's time to take in the car to have the alternator tested. My buddy isn't showing up today so maybe tomorrow. >>> Hmm, come to think of it, I should put the charged battery back into the >>> car and connect it up. If there is a leak in the wiring or other [quoted text clipped - 18 lines] > have the alternator tested. My buddy isn't showing up today so maybe > tomorrow. Hi, Simple way to see excess ghost current is using a small 12V bulb in seiries with battery cable. There is a very very small amount of current flowing at all times for clock and such. The DVM reading (-) is correct. The battery being the source would read drain current as positive if the red lead was connected to the battery + post. As far as the magnitude goes, did you read with all the accesories off? It strikes me as a tad high, was the dome light on? something else on? Good luck. >>>Hmm, come to think of it, I should put the charged battery back into the >>>car and connect it up. If there is a leak in the wiring or other [quoted text clipped - 19 lines] > have the alternator tested. My buddy isn't showing up today so maybe > tomorrow. > Vanguard wrote: >> [quoted text clipped - 15 lines] > drain current as positive if the red lead was connected to the battery + > post. Yeah, I figured that after thinking about it. The current would go out from the "+" battery post so the red probe on the DVM on there would've been backwards to the electron flow. > As far as the magnitude goes, did you read with all the accesories off? > It strikes me as a tad high, was the dome light on? something else on? The only device that I know of that would've been on was the clock in the radio. No lights, including dome lights, were on. The key was not in the ignition switch so it wasn't even partially turned to enable some of those circuits. I figured if a diode in the rectifier were shorted then that might be the cause of the drain through it. I found a basic schematic at: http://www.alternatorparts.com/understanding_alternators.htm If a diode were shorted, wouldn't that mean that there would be current flowing through it (back to ground)? I always thought a diode would blow open due to the heat of the leakage current but then these are high-current diodes and the leakage current is only half an ampere. > Yeah, I figured that after thinking about it. The current would go out > from the "+" battery post so the red probe on the DVM on there would've [quoted text clipped - 17 lines] > blow open due to the heat of the leakage current but then these are > high-current diodes and the leakage current is only half an ampere. The reason the amp draw may be a little high is because of the keep alive memory in the radio and computer. Here's how to get around that. Hook up your amp probe as before between the +post and +cable. Now take a jumper wire and place it between the +post and +cable. Leave it there for at least 15 seconds (some take up to a minute). At this point your amp probe will read zero. Once you remove the jumper wire the probe should read much lower than in your initial test. All that is moot though as I agree with JohninKY's original post, you have a bad diode since it's only charging 12.5 volts. BTW... that shop that says they can't jump the car, then test the alt is suspect. It sounds like they have an idiot proof tester of some sort and only have idiots to test with. ;-) NAPA sells a very good reman alt with a lifetime warranty. Be sure to ask for their premium line as they also have a cheaper line with a 3 year warranty. They also sell a new one for many applications for not too much more. > The reason the amp draw may be a little high is because of the keep alive > memory in the radio and computer. Here's how to get around that. Hook up [quoted text clipped - 14 lines] > warranty. They also sell a new one for many applications for not too much > more. PS I just reread your first post. That $118 alt from Pep boys is a great price for a lifetime warranty! I once bought a $22 alt for a Chevy from AutoZone. I asked if they had anything of better quality. He said it had a Lifetime Warranty so I bought it. Darn thing lasted 8 years! >> NAPA sells a very good reman alt with a lifetime warranty. Be sure to ask >> for their premium line as they also have a cheaper line with a 3 year [quoted text clipped - 5 lines] > AutoZone. I asked if they had anything of better quality. He said it had a > Lifetime Warranty so I bought it. Darn thing lasted 8 years! Each of the stores that I went to (after checking the warranty and price) is selling a rebuilt for $118 to $129 and each has a lifetime warranty (the $129 unit include roadside assistance to get a jump if the battery is bad or, in this last case, the alternator won't charge the battery so the battery is dead and I need a jump to start the car; didn't get any details on how long that plan lasts). As I recall, Napa's rebuilt ran around $179 for standard quality, $224 for premium, and $290 new. This is for an old 92 Subie Legacy that gets maybe 7K miles on it per year. I figure if it has a lifetime warranty (for the original car in which it gets installed) then I can pop in another if it fails. PepBoys has been around long enough that they'll probably still be around for years from now. O'Reilly has been around for maybe a couple decades (but when through name changes). There are some things I won't buy from either, like brake calipers or wheel bearing, but a lifetime alternator is okay. Replacing the alternator is not much more difficult than taking out the battery. Making sure I don't overtighten the belt is the only hazard. > The reason the amp draw may be a little high is because of the keep alive > memory in the radio and computer. Here's how to get around that. Hook up [quoted text clipped - 3 lines] > read zero. Once you remove the jumper wire the probe should read much lower > than in your initial test. Presumably the half ampere was flowing through the DVM (to measure it at that rate) was for the clock/radio but I don't know if I left it connected long enough to setup the clock/radio. I do know what you're talking about because I had to replace the clock/radio (twice because the salvaged unit failed but I removed its face to put on another salvaged unit whose display was faded and had an iffy press button). I can try what you suggest to see if the current draw drops after, say, a minute of shorting the battery "+" to cable. > All that is moot though as I agree with JohninKY's original post, you have a > bad diode since it's only charging 12.5 volts. BTW... that shop that says > they can't jump the car, then test the alt is suspect. It sounds like they > have an idiot proof tester of some sort and only have idiots to test with. The idea is to also measure the surge current while or after starting. Although the battery itself passed their automatic tester (first a handheld one and then in a load tester), they said one of the tests is during startup. So, yeah, it might be an idiot tester but it's free at the stores. A more complicated tester involving human cognition would cost money. The one store said that the alternator can be tested in the car. The others want me to yank it out so it can be mounted on their tester (so its belt runs the alternator). While the alternator isn't that tough to remove (and put back in), I'd rather not do it if not necessary, plus an in-car test might find a different problem, like a short in the harness, a short in a dash guage, or whatever. I'm sure that whatever tester is used at whichever car part store would all qualify as an idiot tester: follow hookup procedure, press a button, and wait for a good/bad status. An idiot tester that tests with the alternator in the car just makes it simpler for me to do the test. > While the alternator isn't > that tough to remove (and put back in), I'd rather not do it if not > necessary, plus an in-car test might find a different problem, like a > short in the harness, a short in a dash guage, or whatever. You're making this more complicated than it is. Shorts cause fuses and fusable links to burn out, not drag the voltage output down. You've already determined the alt can't put out more than 12.5 volts even though your battery voltage was well below that. It should have been putting out 13.8v, if not more on a dead battery. If you had a problem with your harness or dash gauge not energizing the alt, or the alt voltage not getting to the battery, the battery voltage would have read well below 12 volts, not 12.5v. 12.5v is sort of a magic number. It shows the alt is trying but one of the diodes is burned out. Testing it for amperage output like the shops want to do, whether on car or on the bench tester, or testing for starter draw while cranking, isn't going to show a different result. You really need another alt. > Shorts cause fuses and fusable links to burn out, not drag the voltage > output down. Let me rephrase that: Shorts cause fuses and fusable links to burn out, not drag the voltage output down - for more than a few seconds anyway. >> While the alternator isn't >> that tough to remove (and put back in), I'd rather not do it if not [quoted text clipped - 15 lines] > or on the bench tester, or testing for starter draw while cranking, isn't > going to show a different result. You really need another alt. Dontcha hate it when they never come back to tell you you were right, and thanks for the help. I know I do. </talking to myself> > Dontcha hate it when they never come back to tell you you were right, and > thanks for the help. I know I do. </talking to myself> just wantja to know..I feel your pain. >>> While the alternator isn't >>> that tough to remove (and put back in), I'd rather not do it if not [quoted text clipped - 18 lines] > Dontcha hate it when they never come back to tell you you were right, and > thanks for the help. I know I do. </talking to myself> I haven't had the time to take in the car. As I said, it usually just sits in the carport. Since last November, I've probably put around a hundred miles on it. Also, I was going to have my buddy come along in case there was a problem with the car on the way to or back from the car shop but he didn't call last weekend, I couldn't reach him, and he called on Thursday to say he'd stop by to drop off his trailer (for yard waste removal) but had to leave to prepare for his son's cub scout trip that he was leaving on. A family member kept disappearing when they said that they would help. I'd be pissed with both people if it weren't that this is still a low priority repair. I really only have the weekends to get at this problem but have gotten disappointed the last 2 weekends with promises of help but didn't get any. I put the DVM from the "+" battery post to the cable and saw no amperes this time. Was a bit surprised that there was no current flow but then found out the 2A slowblow fuse had blown. So I'll disconnect and recharge the battery and just remove the alternator to get a new one. Everything points at the alternator so I'll just yank it out and get another one (with a lifetime warranty this time). > All that is moot though as I agree with JohninKY's original post, you have a > bad diode since it's only charging 12.5 volts. BTW... that shop that says > they can't jump the car, then test the alt is suspect. It sounds like they > have an idiot proof tester of some sort and only have idiots to test with. Got a new alternator. Didn't bother driving in the car or removing the old one to have it tested. Nothing else looked like the culprit than the alternator. Used my newer car to pickup the alternator (from PepBoys, $118 rebuilt, lifetime warranty), put it into my old 92 Subie, and tested the voltage. The battery had already been fully charged. Voltage was 13.93V so it was definitely above the 12.5V before. It wasn't the 14.4V that I thought it was supposed to get to but the battery was charged and I didn't have another person available to rev the engine while it monitored the voltage to see if it went up. So it looks okay for the alternator. I drove the old car back to the car store for the core refund. Smelled something. Nope, not the alternator (I've smelled a burnt alternator whose bearings went before and it wasn't that varnish smell from the bearings getting super hot and heating up the windings). It came from one side. Good grief, now the front right brake is dragging. I put my hand on each wheel (well, on the wheel cover) and the front right was significantly hotter. Could be some rust on the slider pins is the problem since the car has been sitting idle in the car port for 8 months and maybe just driving it some will get rid of the problem. But just in case, I'm hunting around for a brake inspection, preferrably free. I'll take it back to where I had the brake pads replaced last summer. They worked on the calibers instead of replacing them and one had a rust ring on one of the slider pins that they had to burnish off. Might be the same problem again. |
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