Last Thursday my 1989 240dl died and would not start in the gas station lot. I replaced the battery recently so i tested the alternator and it was not pushing enough power to the battey, but was pushing some. i decided to replace the alternator myself, and I was disconnecting the old alternator electrical leads, when I found that the ground had been frayed and severed. So, I know I need to replace the ground, but I do not know where it used to connect to the chassis or engine. I also am wondering about doing a "perfect ground" direct to the negative battery terminal. Is that wise? Supposedly this can boost the power output. Also, if I replace the ground, is that likely to fix my alternator woes? Or will I have to replace that as well? Will a newer alternator give more power? I am curious because I would like to rewire the cigarette lighter for more power so that it can actually charge my phone. Thank you for reading and for any advice. Cheers from Eugene, Or, the Volvo 240 captial of the west coast

 

If you are taking out the alternator take it to an auto parts store and have them test it. As for the ground all you need is to ground it to the engine block. A charged battery voltage without starting the car should be 12.6 volts. The battery voltage with a running engine should be between 13.2 to 14.2 volts. Your cigarette lighter will be the same.

 

Is there a nut or bolt that the ground commonly connects on the engine? I can't find the other end of the frayed ground wire. Also, currently my cigarette lighter will not charge my phone, this was true as long as I have owned the car (a year now) before I noticed anything with the alternator. Is this just something where old cars were not made with charging smart phones in mind? Can I fix something, or alter something, to get more juice?

 

have you checked the voltage at your cigar plug? could be lots of problems there, but it certainly should be able to handle the 10 watts or so a typical USB charger takes. I'd be checking the fuse its on, those 240 tinplate ceramic fuses are pretty crappy. best thing you can do with them is replace ALL the fuses with Flosser ceramic fuses that have copper or brass elements, these are often sold in kits as mercedes w123/w124 fuses on ebay, etc.... clean each fuse spring contact before installing the new fuse, I use a soft pink pencil eraser for this.

 

I'm vaguely remembering the alternator ground wire going to a oil pan bolt, but don't quote me on this.

 

Thank you all for the replys. I found the other end of the ground, it terminated on a bolt on the alternator mounting bracket (the furthest aft bolt on #5 on the attached exploded view). I replaced the wire (about 4" worth) after getting the old alternator tested on the bench at oriley's and it comming back good. So, I returned today to oriley's to check my work and their machine told me the internal voltage regulator was still bad. I took it to AutoZone and it was the same thing. I took it to shelby's auto elecrics and he put a voltage meter at the battery and at the alternator and everything was doing fine. i am a firat time car owner, and this was my first go at being a mechanic. I just ordered a voltage meter of my own, a 240 repair manual and a new set of fuses. This was confidence inspiring, and I owe that to the helpful folks here. It's a great community, keep doing it please.

 

glad you got it fixed. just a word of caution about charging smart phones through the cigarette lighter outlet. if you are using a lighter to usb cable converter be careful.
i fried a smart phone doing this. not pretty...

 

I've been using USB cigar chargers for years, as long as you use quality ones, they are fine.

 

probably mine is not a good quality.. made in china etc.. but it worked for other stuff. it just fried the smart phone... just sayin..

 

one complication with USB chargers, there's a couple different specifications now. The "Qualcomm Quick-Charge" stuff VIOLATES the USB C specification by raising the voltage. I would be careful NOT to plug a native USB C phone, such as a Pixel, into a Qualcomm QC charger. The native USB C phone charging method is up to 3 amps at 5V. The older USB charging spec was 5V at 2 amps max, and the *original* USB power spec was 5V at 0.5 amps.

If you do have a rapid charging phone (either USB C or Qualcomm QuickCharge) be *SURE* to use high quality cables for charging it.