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Car Forum / Dodge / Dodge Trucks / August 2007Bad Diode Stator means?
Sorry to keep bugging everyone about this, but I just don't know. 77 dodge van 318. On startup ammeter needle swings from full charge to midrange. Loud squealing when ammeter needle swings to full charge. Noise goes away after engine warms up. I think I tried tightening the belt long time ago and made no difference. Visual inspection of belt appears ok. It is one of those kind that is serrated on the pulley side, but no glazing or obvious wear. Looking at a shop diagnostic report sheet from long ago it is somewhat illegible but says, under "Alternator Output: Bad Dode stator" which I guess legibly written means: Bad Diode Stator? Would this cause the noise? The belt looks ok and I brought the alternator down to Autozone for them to test on their machine. Test said it was ok, but Mgr. there said it was probably a bad diode in the alternator. Should I buy a new alternator and see if the noise disappears? > Sorry to keep bugging everyone about this, but I just don't know. > 77 dodge van 318. On startup ammeter needle swings from full [quoted text clipped - 11 lines] > there said it was probably a bad diode in the alternator. > Should I buy a new alternator and see if the noise disappears? ======= ======= Informative diagnostic post.... good for you..... Addressing your LAST question in the post........ NO!!!!!!!!!!!!!!!! not yet. The needle should raise on ANY vehicle, momentarily after startup as the generator recharges the battery. (fact, not fiction) I would not condem the altenator yet, as long as the charging system seems to be doing it's primary job, and your main symptom is the noise. Keep your money in your pocket for now. now ..as to the topic, and your main concerns... being a tech....i would'nt suspect the stator making the noise, but that doesn't eliminate the FACT that it still could be the altenator making the noise, or the stator for that matter. Quite frankly....i don't know. I defer to higher minds, which will be with you shortly if you're patient. On closing..... You should be informed that I AM NOT..... a fan of AutoZonedOut parts.....especially electrical anything!! with that said....... :) still..... jest to see........ you could ALWAYS....carry it back if the noise didn't go away, or..even if it did. :) and.....i wuddn't feel to baddly bout doin it if i was you...after all.....the Dealer techs do it all the time. :) ~:~ MarshMonster ~takes a sip of his shroom juice...and tries to remember what the inside of an altenator looked like....20 years ago~ ~:~ Bad diode can cause this noise: "I had a funny noise under the hood of my 89 Taurus that no one could identify. It varied with engine speed but could not be localized, even by a Ford technician that I respect. Finally on a trip through Nebraska I had an occasion to take the car into a Ford garage in Scottsbluf . I asked if anyone there might know what I had been hearing, one of their young technicians came over and pulled off the alternator connector. The noise went away. He explained that when a diode fails the unbalance in the alternator magnetic circuit causes the whine. About 6 months later the alternator had to be replaced and of course the noise was gone." http://www.misterfixit.com/altnoise.htm >> Sorry to keep bugging everyone about this, but I just don't know. >> 77 dodge van 318. On startup ammeter needle swings from full [quoted text clipped - 71 lines] > like....20 years ago~ > ~:~ >He explained that when a diode fails the unbalance in >the alternator magnetic circuit causes the whine. About 6 months later >the alternator had to be replaced and of course the noise was gone." THis is true, usually in the form of a loud whine that varies with RPM. Alternators are 3 phase Delta wound and have 6 output diodes for full wave rectification of each phase. When you loose one output will drop some. If you have access to a scope you can find/verify a bad output diode(s) in a flash ----------------- TheSnoMan.com >>He explained that when a diode fails the unbalance in >>the alternator magnetic circuit causes the whine. About 6 months later [quoted text clipped - 7 lines] >----------------- >TheSnoMan.com holy God of all that is Holy. snotroll is back. the man of few words (which is good since the idiot can not spell, write or express himself beyond the second grade) ((ok roy, larry and all the rest that have experienced snotroll, i understand that i am being quite liberal when i use the second grade standard to evaluate snotroll, but i feel that i must be somewhat liberal in order to be completely fair to the snotroll)) returns with an idea. of course the idea probably doesn't make any sense (i must say probably because the idiot posts to every problem that he can find and the law of averages says that even he, being of very unsound mind, will be right once in a while have an answer that in some way may have some degree ofaccuracy, even though it will be difficult to find) but for him, posting an answer in itself is an accomplishment. please however, do not rely on the answer to be accurate or in any way to provide you with any direction whatsoever to fix whatever problem you may have, because if you follow the snotroll, the f.cker may just kill you with his advice. now i will await the vengence of the one called beryll, also know as sheryll the cross dresser, who follows snotroll around and defends his right to be so totally wrong that he is dangerous. >holy God of all that is Holy. snotroll is back. the man of few words >(which is good since the idiot can not spell, write or express himself [quoted text clipped - 16 lines] >sheryll the cross dresser, who follows snotroll around and defends his >right to be so totally wrong that he is dangerous. Such a child but please get your fix. Anything to help you with the teribble insecurity you must have. ----------------- TheSnoMan.com >>holy God of all that is Holy. snotroll is back. the man of few words >>(which is good since the idiot can not spell, write or express himself [quoted text clipped - 21 lines] >----------------- >TheSnoMan.com you are way too kind, but never the less i do appreciate that you so willing to provide an avenue of enjoyment. Why not just junk it and send it to the salvage yard, instead, and buy a another vehicle? Larry : drop some. If you have access to a scope you can find/verify a bad : output diode(s) in a flash : ----------------- : TheSnoMan.com  SignaturePosted via a free Usenet account from http://www.teranews.com And again from a third source confirms this: "Whining A whining noise can be caused by shorted diodes or stator, or by a dry rotor bearing. A quick way to test for the cause of a whining sound is to disconnect the wiring to the generator. Then start and run the engine. If the noise is not there, the cause of the noise is a magnetic whine due to shorted diodes or stator windings. Use a scope to verify the condition of the diodes and stator. If the noise remains, the cause is mechanical and probably due to worn bearings." (don't have the url handy, it's from the autozone site) SnoMan <admin@snoman.com> wrote in news:5ecab3155cqfcouu2hc561gl5uc7a5mejb@ 4ax.com: >>He explained that when a diode fails the unbalance in >>the alternator magnetic circuit causes the whine. About 6 months later [quoted text clipped - 7 lines] > ----------------- > TheSnoMan.com You fools are just Too much! Not only does Snojob give out DEADLY advise that 'WILL" get people killed of they follow it on a bunch of groups I have had the misfortune of the f.cker stalking me on, he now has total Bullshit back up! He/it just must 'love' the abuse for his BS, there can be no other reason for a sane person posting. Read the Original post!!!! To Quote: On startup ammeter needle swings from full charge to midrange. Loud squealing when ammeter needle swings to full charge. END Quote. The OP has a squeal on start up, not a whine when running! Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's - Gone to the rust pile... Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) > And again from a third source confirms this: > [quoted text clipped - 25 lines] >> ----------------- >> TheSnoMan.com > You fools are just Too much! > [quoted text clipped - 6 lines] > > Read the Original post!!!! Mike, he hasn't shown up here in over a month. I chopped the cross post. Roy > To Quote: > On startup ammeter needle swings from full charge to midrange. Loud [quoted text clipped - 39 lines] >>> ----------------- >>> TheSnoMan.com Damn it guy! put your sock puppet away will ya! >Damn it guy! put your sock puppet away will ya! just hold on a bit. beryll should show up soon, telling us why snoidiot isn't as big an idiot as we say......(i think berryl thinks that snoidiot is just a normal idiot rather than a huge idiot) ........and that will be shortly followed by tbone, who will tell us that it is not nice to say naughty things about snoidiot and that it just makes us look bad to make fun of him so we should just say nice things. then some of us will be able to excercise a little bit and play with them. >>Damn it guy! put your sock puppet away will ya! > [quoted text clipped - 8 lines] > then some of us will be able to excercise a little bit and play with > them. Damn!! Pal ya gotta out or something. Looking at the crotch cannibal and the Idiot as exercise? There is nothing to it. T-bone on the other hand, has gotta know he cracks me up when he try's to become the voice of reason.<GBFG> > >>Damn it guy! put your sock puppet away will ya! > > [quoted text clipped - 13 lines] > gotta know he cracks me up when he try's to become the voice of > reason.<GBFG> It really has nothing to do with the "voice of reason" and I'm glad that I make your day. The sad thing is that you guys are doing the very thing so many of you jumped on me for doing so I'm not going to say anything else about it. I'll just sit back and laugh. SignatureIf at first you don't succeed, you're not cut out for skydiving >> >>Damn it guy! put your sock puppet away will ya! >> > [quoted text clipped - 19 lines] >many of you jumped on me for doing so I'm not going to say anything else >about it. I'll just sit back and laugh. i really didn't mean it as a slam tom, relax. we are what we are. accept it and move on. you contribute quite abit on the ng too. >> >>Damn it guy! put your sock puppet away will ya! >> > [quoted text clipped - 17 lines] > It really has nothing to do with the "voice of reason" and I'm glad that I > make your day. No, you don't make my day. Although when you admonish somebody I do chuckle. >The sad thing is that you guys are doing the very thing so > many of you jumped on me for doing Huh??? so I'm not going to say anything else > about it. This I gotta see! <VBG> >I'll just sit back and laugh. There ya go! It is entertainment. >>He explained that when a diode fails the unbalance in >>the alternator magnetic circuit causes the whine. About 6 months later >>the alternator had to be replaced and of course the noise was gone." Damn too much time in the sun and I missed this. I just gotta fix the Idiot's post > THis is true, usually in the form of a loud whine that happens whenever > the Idiot gets caught posting BS info> If you have access to a Bullshit > Detector you can find/verify a bad bunch of info posted by the IDIOT > TheIdiot.com You could be describing a polished or loose belt. I test them by taking a cold off engine and seeing if I can hand spin the alternator pulley. If I can. it will for sure slip under load and make the noise you describe. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's - Gone to the rust pile... Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) > Sorry to keep bugging everyone about this, but I just don't know. > 77 dodge van 318. On startup ammeter needle swings from full [quoted text clipped - 11 lines] > there said it was probably a bad diode in the alternator. > Should I buy a new alternator and see if the noise disappears? >Sorry to keep bugging everyone about this, but I just don't know. >77 dodge van 318. On startup ammeter needle swings from full [quoted text clipped - 3 lines] >inspection of belt appears ok. It is one of those kind that is serrated >on the pulley side, but no glazing or obvious wear. The belt might be squealing because the alternator is dragging. Or, maybe the belt is just slipping. >Looking at a shop diagnostic report sheet from long ago it is somewhat >illegible but says, under "Alternator Output: Bad Dode stator" which I >guess legibly written means: Bad Diode Stator? Would this cause the >noise? The belt looks ok and I brought the alternator down to Autozone >for them to test on their machine. Test said it was ok, but Mgr. >there said it was probably a bad diode in the alternator. This is a diagnostic report sheet from a different problem, though, isn't it? It's possible you have an intermittently bad diode. But you don't know for sure if the problem isn't repeatable. >Should I buy a new alternator and see if the noise disappears? I'd buy a new belt, and I'd buy it from the dealer and not from Autozone. I might consider looking at the alternator if that doesn't fix it. --scott Signature"C'est un Nagra. C'est suisse, et tres, tres precis." "Scott Dorsey" <kludge@panix.com> wrote in message news:f934et$dj5 > This is a diagnostic report sheet from a different problem, though, isn't > it? It's possible you have an intermittently bad diode. But you don't > know for sure if the problem isn't repeatable. > --scott Agree, Scott. I dont think that anyone has mentioned, yet, that diodes can fail in either of two modes....shorted or open. And either can be permanent or intermittent. The consequences of those failure modes can present different symptoms. Either should be easy to diagnose if you have the ideal equipment (which most of us do not). >Sorry to keep bugging everyone about this, but I just don't know. >77 dodge van 318. On startup ammeter needle swings from full [quoted text clipped - 3 lines] >inspection of belt appears ok. It is one of those kind that is serrated >on the pulley side, but no glazing or obvious wear. Take a ten dollar bill and go get a new belt and a piece of sandpaper. Use the sandpaper to lightly buff the groove the belt rides in. Just enough to breakup any glaze that might be present. Put on the new belt and tighten it properly. No more problem. Replace the third lugnut on the left rear tire at the same time. Steve B. >>Sorry to keep bugging everyone about this, but I just don't know. >>77 dodge van 318. On startup ammeter needle swings from full [quoted text clipped - 11 lines] > > Steve B. It is easy to test too. Just spray some WD-40 on the belt when the noise is happening........... If it goes away, it is the belt. Ed > Sorry to keep bugging everyone about this, but I just don't know. > 77 dodge van 318. On startup ammeter needle swings from full [quoted text clipped - 10 lines] > for them to test on their machine. Test said it was ok, but Mgr. > there said it was probably a bad diode in the alternator. So what to do. Do you believe the test or do you believe the manager. It would seem to me that if they have a machine to test alternators it would be able to detect a bad diode. > Should I buy a new alternator and see if the noise disappears? What is the noise? Your description leads one to believe the noise is the belt slipping. If that is where the noise is coming from it is unlikely to be a bad diode. By now one would guess that you have probably overtightened the belt so the belt being too loose can be ruled out. If your gauge truly measures amps then it is normal for the amp rate to go high after starting. It may be that it always did exactly what it is doing now - only you never noticed because there was no loud squeal to draw your attention to it. Or it could be that it is now charging more than it used to because of a bad starter or bad engine or some other unknown draw on the battery that requires a lot of amps to restore the battery. A weak diode could be draining the battery. Another possible cause of the problem is a bad belt or the wrong belt for the application. I assume this is a v-belt so the cause could be a worn pulley given that the vehicle is 30 years old. If the pulleys and belt don't fit together as designed you can get the symptoms you describe. -jim hmmmmmmm........ ~:~ marsh ~takes a toke......grabs the remote..... turns the volume up on his favorite sitcom........good stuff~ ~:~ > hmmmmmmm........ > [quoted text clipped - 4 lines] > sitcom........good stuff~ > ~:~ LOL... puff the magic dragon > Sorry to keep bugging everyone about this, but I just don't know. > 77 dodge van 318. On startup ammeter needle swings from full [quoted text clipped - 11 lines] > there said it was probably a bad diode in the alternator. > Should I buy a new alternator and see if the noise disappears? Alternator tests OK? Leave it alone (for now). The squealing is a symptom of a belt problem. Either worn, glazed, or loose. How many belts does this vehicle have? It might not even be the alternator belt. Check them all. SignaturePaul Hovnanian mailto:Paul@Hovnanian.com ------------------------------------------------------------------ Where am I going, and what am I doing in this handbasket? |
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