boxerlover Posted July 15, 2006 Share Posted July 15, 2006 OK. I'm stumped. 86 GL 4WD wagon. Carbed. New rebuild. The tach has started to be erratic and vary 1000 rpm or so while driving. It seems like it does it when it is up to operating temp. Haven't noticed it when cold. I searched the archives and conventional wisdom says coil or disty. I suspected and replaced the coil. A marginal improvement. Or so it seems. But here's the weird thing. When messing with it today. It gets worse with the heater fan speed. The faster the fan runs, the worse the tach jumping around gets. I tried it going up a hill today, and it seems to be missing a bit while the tach is doing the dance, but I don't notice it on level roads. I'm stumped. What could the fan switch have to do with the tach? Any help would be hugely appreciated. BTW- No tach bounce at idle. Link to comment Share on other sites More sharing options...
naru Posted July 15, 2006 Share Posted July 15, 2006 OK. I'm stumped. 86 GL 4WD wagon. Carbed. New rebuild. The tach has started to be erratic and vary 1000 rpm or so while driving. It seems like it does it when it is up to operating temp. Haven't noticed it when cold. I searched the archives and conventional wisdom says coil or disty. I suspected and replaced the coil. A marginal improvement. Or so it seems. But here's the weird thing. When messing with it today. It gets worse with the heater fan speed. The faster the fan runs, the worse the tach jumping around gets. I tried it going up a hill today, and it seems to be missing a bit while the tach is doing the dance, but I don't notice it on level roads. I'm stumped. What could the fan switch have to do with the tach? Any help would be hugely appreciated. BTW- No tach bounce at idle. A weak alternator or bad harness connection come to mind. Consider a loose timing belt for the eratic tach too. Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 15, 2006 Share Posted July 15, 2006 Fan switch has nothing to do with it - it's just creating a draw on the electrical system, and the distributor is no longer able to cope with the lower amps. Your problem is the distributor bushings. I will lay down money on it. Take the cap off and try to move the distributor shaft from side to side. It *should* have no movement. Your's will be very sloppy. The worn bushings are causing the reluctor air gap to vary enough that the distributor is fireing several times for each plug - that's the high RPM reading on the tach. These guys can replace the bushings for about $35 if you dissasemble it for them or about $50 if you have them do it, or snag a JY disty for $20 or so: http://www.philbingroup.com/ GD Link to comment Share on other sites More sharing options...
boxerlover Posted July 15, 2006 Author Share Posted July 15, 2006 Thanks GD. I hadn't thought of the multiple firings causing the issue. I will yank it out on Sunday and have a look. I'll lay odds you are right. It's exactly what the miss feels like. I'd love to have it rebuilt, but it's a daily driver so it looks like I'll have to pop for a rebuilt or used unit. Are the ND and Hitachi disty's interchangeable within the carbed engines? Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 15, 2006 Share Posted July 15, 2006 They are, so long as you also change to the corresponding coil - the different brands have different resistance values and mixing them can damage the ignitor in the disty. Other than that, they will swap with no issues. GD Link to comment Share on other sites More sharing options...
boxerlover Posted July 16, 2006 Author Share Posted July 16, 2006 OK. Now I'm really confused. I got a rebuilt disty that is supposed to be for an '86 carbed model, and noticed right away something was wrong. It's missing a flange for a holddown bolt. Also, gear/shaft arrangement is wrong. It appears that even the gear to flange height is wrong. Pics attached. Original on the left, rebuilt on the right. I've got a Mitchells manual for 1986, and the Hitachi they show looks like the rebuilt unit. To make matters worse, after pulling the original one, I can't feel any freeplay in the shaft/bearing fit. Seems fine to me. So, a couple of question. 1) What is the original distributor? and 2) Where should I go from here? Link to comment Share on other sites More sharing options...
boxerlover Posted July 16, 2006 Author Share Posted July 16, 2006 One other question... On the coil the yellow wires are connected to the neg terminal. The black wires are connected to the pos terminal. Is that right? Seems odd to me. Thanks. Link to comment Share on other sites More sharing options...
naru Posted July 17, 2006 Share Posted July 17, 2006 OK. Now I'm really confused. I got a rebuilt disty that is supposed to be for an '86 carbed model, and noticed right away something was wrong. It's missing a flange for a holddown bolt. Also, gear/shaft arrangement is wrong. It appears that even the gear to flange height is wrong. Pics attached. Original on the left, rebuilt on the right. I've got a Mitchells manual for 1986, and the Hitachi they show looks like the rebuilt unit. To make matters worse, after pulling the original one, I can't feel any freeplay in the shaft/bearing fit. Seems fine to me. So, a couple of question. 1) What is the original distributor? and 2) Where should I go from here? They gave you an ea-81 disty. If your bushings are OK it would be a waste of money anyway. As long as your car isn`t a calif. automatic your disty will be either 22100 AA120 or 121. Like I tried to tell you before,if the tach and engine are affected by the heater fan,you have electrical issues. Worn disty bushings don`t enter the picture. I would monitor both DC and AC voltage at the positive supply to the ignition module. Try a different fan too.A very worn one could generate enough electrical noise to confuse some electronics. Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 17, 2006 Share Posted July 17, 2006 Like I said - I'll lay money on it - $10 anyone? Who's got paypal? Naru's right on the disty (though not much else I'm afraid ). They gave you one for an 86 Hatchback or Brat. You need to ask for one for an 86 Wagon - that will not confuse them so much. And make sure in the parts catalog they show it's for an overhead cam, and not the overhead valve - OHV is the EA81 version that you have. Incidentally, the disty itself will work, but you would have to swap the drive gears (need to drill a new hole in the shaft), and enlarge the adjuster slot. It *would* work just fine tho. I'm using an EA82 SPFI disty in my EA81 for the fuel injection - works great with the right drive gear. This happens to be an extremely common failure on both types of subaru carbed distributors (do a search if you don't beleive me - I've personally answered a couple dozen threads like this). The ND in my wagon got so bad at 148k original miles, that the tach would intermittantly read 7,000 RPM at idle. Had phiblin (they are local to me) replace the bushings and re-diapham the vac advance. Has been beutiful ever since. They did an awesome job for only $55 too. I've since sent a number of people their business and everyone has been pleased. GD Link to comment Share on other sites More sharing options...
naru Posted July 17, 2006 Share Posted July 17, 2006 Like I said - I'll lay money on it - $10 anyone? Who's got paypal? Naru's right on the disty (though not much else I'm afraid ). They gave you one for an 86 Hatchback or Brat. You need to ask for one for an 86 Wagon - that will not confuse them so much. And make sure in the parts catalog they show it's for an overhead cam, and not the overhead valve - OHV is the EA81 version that you have. Incidentally, the disty itself will work, but you would have to swap the drive gears (need to drill a new hole in the shaft), and enlarge the adjuster slot. It *would* work just fine tho. I'm using an EA82 SPFI disty in my EA81 for the fuel injection - works great with the right drive gear. This happens to be an extremely common failure on both types of subaru carbed distributors (do a search if you don't beleive me - I've personally answered a couple dozen threads like this). The ND in my wagon got so bad at 148k original miles, that the tach would intermittantly read 7,000 RPM at idle. Had phiblin (they are local to me) replace the bushings and re-diapham the vac advance. Has been beutiful ever since. They did an awesome job for only $55 too. I've since sent a number of people their business and everyone has been pleased. GD "To make matters worse, after pulling the original one, I can't feel any freeplay in the shaft/bearing fit. Seems fine to me." Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 17, 2006 Share Posted July 17, 2006 It doesn't take much - just a tiny bit on the ND's - little more on the Hitachi. His is only jumping about 1,000 RPM's. Mine (being a ND) didn't have much play either - maybe 1/32" or less. Still jumped thousands of RPM's all by itself. It was random - wouldn't happen at all sometimes, and then one day it got so bad I could barely drive it home from work. Wouldn't go over 50 MPH without a fight. Too much random plug fireing. Bad juju. The reluctor air gap is meant to be set with a feeler guage, and is a close tolerance component. Small fractions of an inch are important. GD Link to comment Share on other sites More sharing options...
naru Posted July 17, 2006 Share Posted July 17, 2006 It doesn't take much - just a tiny bit on the ND's - little more on the Hitachi. His is only jumping about 1,000 RPM's. Mine (being a ND) didn't have much play either - maybe 1/32" or less. Still jumped thousands of RPM's all by itself. It was random - wouldn't happen at all sometimes, and then one day it got so bad I could barely drive it home from work. Wouldn't go over 50 MPH without a fight. Too much random plug fireing. Bad juju. The reluctor air gap is meant to be set with a feeler guage, and is a close tolerance component. Small fractions of an inch are important. GD "Fan switch has nothing to do with it - it's just creating a draw on the electrical system, and the distributor is no longer able to cope with the lower amps." So,what do you mean by this? "lower amps"?? Is the electrical system working or not? Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 17, 2006 Share Posted July 17, 2006 When the fan cuts on, it draws a lot of amps out of the system - the reluctor air gap is fireing too often (any VERY close together). The coil isn't charging as much durring this very small interval, and when the plug fires a second time, the spark is weak. Multiple sparks - some weaker and some stronger are causing the distributor to have dis-proportionate forces on the shaft bushings. They start to oscilate, and in the case of mine, it was actually audible - sounded almost like a lifter tick, but much faster. The sound, and jumping tach came and went together. High draw on the electrical system can induce this behaviour.... at least that's my theory on the matter. Can't see what's going on in there unless I could lay hands on a clear plastic disty cap (wouldn't that be neato? ). GD Link to comment Share on other sites More sharing options...
boxerlover Posted July 17, 2006 Author Share Posted July 17, 2006 Guys, I really do appreciate the help. You are right GD. The stock one is numbered 22100 AA 121. I didn't realize there were different disty's depending on the model. Naru- I think the alternator is OK. No charging issues or wild voltage swings. Runs about 12.9 volts at idle. I haven't checked it digitally at speed, although the stock volt meter shows about 15 volts on the road. Not sure how accurate that gauge is though. I also have ruled out timing belts. They are brand new and tight. Here's another piece to the puzzle. In addition to the fan, it will very occasionally start jumping around if the turn signals are on. Headlights don't seem to have an effect on it. Also, it doesn't jump around at idle at all. It's rock solid there. It needs to be running around 2K or above for this to happen. It also doesn't do it when the engine is cold. The engine has to be up to full operating temp. This is why I originally replaced the coil. I thought it was failing at temp. I'm not sure how to isolate this without dropping the coin for a new disty, which I already did but will now return since they gave me the wrong one. Prior to buying the new unit, I felt for some slop in the disty while it was mounted in the car and thought I felt a little. However, when I took it out and checked it, my precision calibrated fingers say there is no more than .0010-.0015 clearance. If it is a harness connection, it's gonna be a *************** to track down. My wiring diagrams (courtesy of Chilton's) suck. GD- given that the fit in the disty seems OK, would you still suspect it might be the problem? Naru- if I want to check voltage, am I checking at the positive coil terminal? I'm still confused by the black wire being hooked to the positive coil terminal. Chiltons is no help in this regard. I'm at a loss guys. My daughter wants her car back and she's getting tough to live with. Any further thoughts? I'm desperate! Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 17, 2006 Share Posted July 17, 2006 It's possible you have a bad ignitor inside the disty as well - perhaps it's gone too sensitive or something. It is usually tough to notice the shaft play once it's out of the vehicle. With it in there, the thing is held solid, and it's easier to notice the movement. It really doesn't take much. The shaft oscillation might not set in till the shaft starts spinning faster - this is all sounding pretty normal for the beginnig stages of shaft play. Slightly abnormal tach readings at higher RPM, and weird effects with accesories turned on are just the start. Most people who have this problem don't notice till it gets REALLY bad, and starts making noises, and the tach starts jumping around at idle too. I knew something was up, but being poor at the time I had to drive it. Eventually it go so bad I had to find a solution - I found philbin, and was out my ride for a grand total of 48 hours. Oh yeah - and the coil is right - black/white stripe goes to +, and yellow goes to -. I always remember it cause the yellow tach signal always goes to the negative side of the coil..... GD Link to comment Share on other sites More sharing options...
naru Posted July 17, 2006 Share Posted July 17, 2006 When the fan cuts on, it draws a lot of amps out of the system - the reluctor air gap is fireing too often (any VERY close together). The coil isn't charging as much durring this very small interval, and when the plug fires a second time, the spark is weak. Multiple sparks - some weaker and some stronger are causing the distributor to have dis-proportionate forces on the shaft bushings. They start to oscilate, and in the case of mine, it was actually audible - sounded almost like a lifter tick, but much faster. The sound, and jumping tach came and went together. High draw on the electrical system can induce this behaviour.... at least that's my theory on the matter. Can't see what's going on in there unless I could lay hands on a clear plastic disty cap (wouldn't that be neato? ). GD Sorry,but that theory doesn`t fly. You are saying that the alternator is unable to maintain charging voltage w/the added current draw of the fan. Only way that would be true is if it was weaker than expected or we would all have jumpy tachs w/the fan on. Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 17, 2006 Share Posted July 17, 2006 They are 50 amp, and that's at like 3k RPM. Not very much. GD Link to comment Share on other sites More sharing options...
boxerlover Posted July 18, 2006 Author Share Posted July 18, 2006 The quest continues. I ran the car tonight with a digital voltage meter in the cigarette lighter and my VOM hooked to the coil hot side. I went for a drive and the voltage on both went to a high of about 16.1 volts. That seems a little high to me, but nonetheless, both meters correlated. Turned on the fan and the tach started its dance, but no indication of voltage problems on either meter. I went home and hooked up an inductive tach to the plug wire, and ran it up to 2500 rpm. Inductive tach steady as a rock, and no miss felt. Turned on the fan at which point the instrument tach started its dance, but the inductive tach remained rock solid. Again, no miss felt. Forever whatever reason, I can't get the miss to repeat. Maybe the problem is just a bad tach??? I'm assuming the tach in the instrument panel is nothing more than a glorified voltmeter. Can I hook my VOM to the coil negative terminal and read the signal? What is the output? That is the question for the evening. Then I can correlate it to the tach signal and find out if the tach in the car is bad. I really hate it when I can't get to the bottom of a mechanical or electrical problem. Link to comment Share on other sites More sharing options...
naru Posted July 18, 2006 Share Posted July 18, 2006 The quest continues. I ran the car tonight with a digital voltage meter in the cigarette lighter and my VOM hooked to the coil hot side. I went for a drive and the voltage on both went to a high of about 16.1 volts. That seems a little high to me, but nonetheless, both meters correlated. Turned on the fan and the tach started its dance, but no indication of voltage problems on either meter. I went home and hooked up an inductive tach to the plug wire, and ran it up to 2500 rpm. Inductive tach steady as a rock, and no miss felt. Turned on the fan at which point the instrument tach started its dance, but the inductive tach remained rock solid. Again, no miss felt. Forever whatever reason, I can't get the miss to repeat. Maybe the problem is just a bad tach??? I'm assuming the tach in the instrument panel is nothing more than a glorified voltmeter. Can I hook my VOM to the coil negative terminal and read the signal? What is the output? That is the question for the evening. Then I can correlate it to the tach signal and find out if the tach in the car is bad. I really hate it when I can't get to the bottom of a mechanical or electrical problem. Steady reading on the inductive tach shows the ignition primary and secondary are OK.No need to troubleshoot furthur. Looks like your dash tach is picking up electrical noise from a worn fan motor.A bad dash ground might be an aggravating factor. Tach itself is probably OK. Try taking an AC voltage reading w/the fan on. Link to comment Share on other sites More sharing options...
boxerlover Posted July 18, 2006 Author Share Posted July 18, 2006 Try taking an AC voltage reading w/the fan on. Naru, This may be a dumb question, but where would I take the AC reading at? Not sure what I'm looking for here. Link to comment Share on other sites More sharing options...
naru Posted July 18, 2006 Share Posted July 18, 2006 Naru, This may be a dumb question, but where would I take the AC reading at? Not sure what I'm looking for here. Closer to the tach the better.Lighter should be OK.You are looking for any significant voltage.While you have the meter out,try another reading between the alternator case and large output wire w/headlights on,RPMs up.This will test the alternator for undesireable AC output. Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 18, 2006 Share Posted July 18, 2006 I have seen plenty of bad alt rectifiers, and NEVER has it caused the tach to behave like that. If you were putting out any significant amount of AC current, the various dash indicators would glow faintly - the diodes in the power feed and ground circuits for the indicators will not function properly when the current flow is reversed and thus the incandescent bulbs used in the analog clusters will glow. That's all the indication I've ever seen on a subaru of AC voltage output. You alt output does seem a little high, but that may or may not be related to the calibration of your VOM - ~14.5 is the correct alt output. Although I've seen higher in cases where the remote sensor wire for the alt is corroded at the main junction (the fusible links are the main junction on the older subaru's). You should also be checking the voltage AT the main junction not the alternator. The alternator voltage may increase if the circuit draw at the main junction requires it. 15 or 16 volts is perfectly normal for GM remote sensing alt systems if measured directly off the back of the alternator. GD Link to comment Share on other sites More sharing options...
Cougar Posted July 19, 2006 Share Posted July 19, 2006 Naru, This may be a dumb question, but where would I take the AC reading at? Not sure what I'm looking for here. Measure the power supply voltage but place the meter in the AC volts mode instead of the DC mode. This will show you how much AC voltage is riding with the dc component. Your measurement of the alternator voltage shows that the output voltage is too high. You shouldn't see more than 15.25 volts. The alternator may also be generating noise along with the blower motor. I would recommend you replace the alternator and then see what happens. Link to comment Share on other sites More sharing options...
boxerlover Posted July 23, 2006 Author Share Posted July 23, 2006 Well guys, the problem is solved! I yanked the alternator out and had it tested. Lo and behold, it was bad, pushing out too many volts as expected. Slapped a NAPA rebuilt in, and (drum roll....) problem solved! Steady as a rock now at between 13.4 and 13.9 volts, and NO MORE TACH issues. I would like to thank each and every one of you who responded to help. It was very much appreciated. The collective wisdom of this board certainly put my local mechanic to shame. Thank you all again for taking the time to help and answer what may have been some pretty basic questions. USMB rules! Link to comment Share on other sites More sharing options...
Cougar Posted July 23, 2006 Share Posted July 23, 2006 Another case solved. Glad you got it fixed, and thanks for the feedback. Link to comment Share on other sites More sharing options...
Recommended Posts
Please sign in to comment
You will be able to leave a comment after signing in
Sign In Now