2 electrical problems plus.......

J

John Buchtenkirch

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I have been working on my coupe 3 or 4 nights a week for a few hours sorting out problems, finishing off this & that and then taking it for test runs in the middle of the night. I finally got rid of an absolutely annoying rattle that has been eluding me for almost month (hearing isn’t great after pounding on fenders for 40 plus years) but the plus side is I’ve fixed so many minor rattles that the car is actually pretty tight for an old hardtop. Other than the seats not being nearly as comfortable as my Audi wagon I’m pretty happy with the car but it’s a bit anti-climatic getting it on the road so late in the year. Even though I’ve driven it more at nights I have gotten favorable comments & thumbs up during my few daylight jaunts :).
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I still have a few problems :?: that hopefully someone may be able to point me in the right direction on. About 3 weeks ago I installed Hella quartz headlights that my good friend Jimmy Dee donated. Only a few nights ago the low beams started going dim for a few minutes, then they get bright for a few more and then dim for a few and so on & so on. The bright lights don’t seem to have the same problem at all ! One friend suggested cleaning the grounds which I did with no improvement. Jimmy tested the alternator this morning and felt it was weak, he suggested I replace it and the battery which he dated from 1996 !!! While the battery is certainly overdue I just can’t understand why a low output alternator wouldn’t show up on the higher drawing high beams ? I absolutely suck on electrical problems but this just doesn’t make sense to me.

A second electrical problem is the lighting for the gas gauge doesn’t come on till 5 or 10 minutes after I turn on the lights ! Then it stays on till I turn off the lights. In the 15 or 20 night time rides I’ve taken this has happened every time !

Finally the speedometer only reads about 60% of the actual speed of the car. The drive gear was missing from the output shaft on the 265 Getrag I got off eBay so I took both gears out of the Bavaria parts car 4 speed. It’s hard for me to believe there’s that much of a ratio difference between the coupe & Bavaria rear ends but I’ve verified the speed difference on several radar speed indicators. Could the speedometer be reading consistently low like that ? Is there any company that specializes in the 265 Getrag that I could buy speedometer gears from ?

THANK YOU FOR EVERYONE'S HELP. Because of all my years of automotive experience and contacts I was a bit over confident going into this but I honestly doubt I would be on the road now without everyone’s help, the whole rebuild / clean up / 5 speed swap was more than I expected. I hope the car is worthy of all your efforts. ~ John Buchtenkirch
 
some problems!

If the alternator was tested and found "weak" by a reliable source, suggest you consider replacing it, and check the mouting bushings while you're at it. Inquiring minds would like to know the manner and extent to which it is "weak".

At the same time, check the brushes on the regulator and the regulated output of the alternator. You can also fit a later internally regulated alternator, delete the yellow stripe box on the inner fender, some wiring, and still run a line to the alternator indicator on the dash. One of these days I'll try that, when I'm ready for more trouble(s).

I'd suggest that the battery is likely okay if it can crank the car, with the ignition disabled, for 10-15 seconds. Assume you know about "float charge" that can start a car in good tune immediately, but fail miserably on the second attempt.

Gas gage lighting issues may be related to a bad ground. 2002 models in particular were notorious for poor instrument cluster grounds. Second choice would be to investigate the dimmer portion of the light switch. Are other cluster lights working okay? Make sure the dimmer wiper is making good contact and that the wound portion is clean and relatively free of corrosion. As an intermittent-to-last resort, I imagine (have not done this) you could take the cluster lights off the dimmer portion of the light switch and leave them on full bright but still switched by the headlights.

I hate intermittent electrical issues but they are a fact of life on older machines. Though my '73 is remarkably free of them, my '85 K100RS can do some very unsettling things on the road, and when it does...

That the speedo reads differently can result from a different ratio in your installed differential (first compare the current and "supposed to be" ratios) and IIRC the gear you inserted into the 265 may not be correct. Others will chime in here but in the end, speedos can be reset to match your diff. Such operations as North Hollywood Speedometer, Palo Alto Speedometer (have I got that right?) and others are qualified to do this work. Do some research before sending your unit off, some of these have better reputations than others but I forget which.
 
John,
I can visualize you driving the coupe on the north shore all the way 25A Ithink it was called... Good memories from Long Island though I was in Suffolk County when I owned the 1977 E24...

The main difference between the high and low beams is that high beams are relayed while low beams go directly through the switch. The main suspect is thus the switch uanble to make a good low resistance contact. It probably heats up and then you lose them until it cools off or something. It is unlikely to be ground because each headlight is grounded separately I recall, so the symptom would not occur at the same time.
It could also be resistance at the fuse.

Simplest test is to bypass the switch, or try a different switch. Checking and cleaning the fuse contact is always good.

As for the gas gauge, it could be +12 or ground problems, the 12V is kind of daisy chained from instrument to instrument so if the others do not have the problem you know it is a local contact problem with that gauge. You have to pull it out and while you are at it you may want to replace all bulbs with 4W bulbs (there is a length compatible version, I can look up the Sylvania model).

Speedometers can break and either show less or erratic speeds, I had one like that I got on ebay, but I cannot say if the transmission gear is the culprit. I am sure others know that.
 
If your battery is that old it could work one day then die the next without warning, I would replace it.

You can buy higher output alternators from BNR on eBay, I put in an 85 amp one from them and it is high quality and will handle any voltage demands.

http://www.ebay.com/itm/BMW-Alterna...e:BMW|Model:3.0CS&vxp=mtr&hash=item519ac7ec6f

If you drive much at night I suggest relaying your low beam circuit - as Arde says the factory setup is weak and after 40 years it's now a liability so consider the relay upgrade:

http://www.e9coupe.com/forum/showthread.php?t=7959&highlight=relay+beam


Your car looks fantastic.
 
Speedometers are configured for specific differential ratios. The transmission drive parts are all the same.

If you change differential ratios, you need to change your speedometer. For example, I put a 3.45 diff in a US 3.0CS which came with a 3.64 diff. I swapped the 3.0 speedometer for one from a US 2800Cs which came with a 3.45 diff. The only problem was that the fonts of the speedometer faces were slightly different.

Another option is that companies like North Hollywood Speedometer can also "regear" your speedometer to suit the diff ratio change.
 
Good link their Steve. I noticed my lights are pretty dim and my dash lights non functioning, so this is timely. Installing a relay on my Corrado made a very large improvement in headlight output.
 
John Buchtenkirch said:
Finally the speedometer only reads about 60% of the actual speed of the car. The drive gear was missing from the output shaft on the 265 Getrag I got off eBay so I took both gears out of the Bavaria parts car 4 speed. It’s hard for me to believe there’s that much of a ratio difference between the coupe & Bavaria rear ends but I’ve verified the speed difference on several radar speed indicators. Could the speedometer be reading consistently low like that ? Is there any company that specializes in the 265 Getrag that I could buy speedometer gears from ?
Click to expand...


As others have suggested, the speedometer is geared/matched to the differential ratio. For this reason, you need to determine exactly what rear end ratio you have installed and attempt to match it with the appropriate gauge assembly - or vice versa. (You can also affect the readout by changing different diameter running wheels/tires, but that is impractical. You could also change the speedo facia to more accurately match your speed, but that might prove very awkward.)

http://www.e9coupe.com/forum/showthread.php?t=6929
http://www.e9coupe.com/forum/showthread.php?t=2464 (Note Gosch's post)
http://www.e9coupe.com/forum/showthread.php?t=1937

As an aside, there is a small company in VA that manufactures odometer gears for cars such as ours. Do not know if they can also provide the requisites for changing the speedo's readout to match your differential, but its worth a shot. :wink:
http://www.odometergears.com/products/BMW/Mechanical+Speedometer/9
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bmw-3.0csi-advert-640x454.jpg
 
Thanks for all the suggestions. I should have mentioned that all my other gauge lights are acting normal, only the gas gauge lighting has the delay. Also if it even makes a difference my coupe is a 1972. ~ John Buchtenkirch
 
The difference in diff ratio is only 5% between the 3.64 and 3.45 and speedos are calibrated in the speedo itself so that won't cause 60% error. Your 73 has no fuse for the headlights so a relay would be a smart investment.
 
Just a suggestion:

On the speedo- try undoing the trip from the bracket temporarily. If it's been removed, disturbed, etc. It can through the odometer slow down the action. If that doesn't do it, then regrease the speedo cable. If you're speedo isn't squealing yet, it's not the problem; at least for now. If there is noise, a drop of super glue on the gear/ shaft will work. Most times it's just spinning rather than turning the gear.

Dash light- series- like a christmas tree string light, so look for the one in the string before the one that acts up.

Light switch- try metering the voltage drop. If it's more than a third of a volt it's too high of a resistance. You can try to take it out, spray it down with contact cleaner. 50/50 shot. But because of the quartz, you need the relay. They take more volts/ amps.
 
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The odometer is a separate mechanism from the speedo.....The shaft that runs the speedo has a gear on it to run the odo.

FWIW I have an '02 that has a perfectly working odometer and yet the speedo has been getting slower and slower over the last year... It now reads about 1/2 actual speed.... But the Odometer still reads right on (ckd with GPS)
I suspect that either the magnetic wheel is driven by the cable is loosing its field strength or there is a bushing wearing out allowing the magnetic disk to move away from the driven disk.
.....Keep meaning to dig into it but haven't had time
Dave Ganzer
 
I replaced the battery today with a new Interstate one. They also put an Interstate print out tester on the car today and the alternator is OK. Made another late night run and after 15 minutes the low beams started the on & off dimming routine so I guess I’m going to add that low beam relay. I would like to know where I can find the high beam relay that’s already in my car ? Thank you. ~ John Buchtenkirch

P.S. The interstate dealer checked the code on the previous battery, it was only 10 years old, not 16. I wasn’t surprised.
 
A low beam relay is unlikely (IMHO) to solve your problem, unless by accident during the install you find and fix the problem.

Identifying those relays will be easy. Key on, high beams on, pull out one of the three relays. If the high beams go out, that's the high beam relay. One of the other relays is for the horn. The function of the third one escapes me at the moment. The rectangular box with the yellow stripe is the voltage regulator. You can test, identify, then label them so next time...
 
What does the fuse controll on the relay that connect to the positive side of battery? It looks like mine has been broke for years and I was going to replace it.
 
The third relay is my added low beam relay, the empty slot for the socket for it was meant for the install of fog lights. My driving lights are relayed but hidden under the headlight access plate.

Honolulu said:
A low beam relay is unlikely (IMHO) to solve your problem, unless by accident during the install you find and fix the problem.

Identifying those relays will be easy. Key on, high beams on, pull out one of the three relays. If the high beams go out, that's the high beam relay. One of the other relays is for the horn. The function of the third one escapes me at the moment. The rectangular box with the yellow stripe is the voltage regulator. You can test, identify, then label them so next time...
Click to expand...
 
I installed the relay in the low beam light circuit and added fuses to both low & high beam circuits today. I took the car out tonight and still the same problem, after 15 or so minutes the lights vary between bright & half intensity. After that disappointment I figured I should get a little more serious with my diagnosing so I parked the car about 6 feet from the garage door to see if road bumps had anything to do with the problem --- intensity still went up & down with the car sitting & running. Then I tried the same thing with the high beams and even though I had initially thought they were unaffected I was wrong, they had the same problem. I still think it was a worthwhile modification but it wasn’t the cure for my problem which was what my buddy Jimmy Dee had predicted all along.

As I write this paragraph it is 6 days later than the one above. Jimmy Dee has brought by some of his test equipment which acts as a volt meter. To our surprise the alternator voltage varied between 13.45 and 18.13 volts !!! So we suspect that the lights were varying between normal output and being ultra bright at times. The alternator has been converted to the attached regulator and Jimmy believes that is what is bad. He is going to call around for parts on Monday and I will report how this turns out. I should have suspected this because the high beams with these Hellas was unbelievably bright. However what I did suspect was the P.O. had oversized bulbs installed. Electrical problems are not my area of expertise. ~ John Buchtenkirch
 
I installed a Bosch rebuilt alternator with the built in regulator yesterday. I took the coupe out last night and the dimming of the headlights problem is history :):) but the low beams sure did burn brighter when the car had up to 18 volts. I also installed a new rubber hose between the gas tank & filler neck and I may have gotten rid of the gas fumes in my trunk, the jury is still out on that one because the auto body business destroyed my sense of smell years ago.

That is probably it for me & the coupe for a month or so, I have to focus on other work I have in my shop for now. We did move a wall in the building about 16” so at least I now have a dry space to store it that’s away from the welding smoke & grinding dust. Maybe if it doesn’t snow I will sneak it out for a few more times but for right now I just need to catch my breath on this coupe deal, I’m kinda burnt out. ~ John Buchtenkirch
 
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