220d reversed polarity
 

Unfortunately i reversed the polarity on the car... Where should i even begin to get this car back roadworthy?

Well fortunately you don't have a lot of electronics in a car that old - I'm assuming your car is from the 1960s or early 70s.

I would start with the alternator and regulator. How much did you operate on the car before discovering the error - did you turn on the key or try to start it (that would be bad, the starter would have rotated backwards in that case).

Is there any obvious damage - did you let the smoke out of anything?

When I was in Tradeschool I was told that all of the Electrical Stuff on the Car actually rund off of the Battery.

The Charging System only charges the Battery.

So if you disconnect the wiring from the Alternator, charge up or get another Battery you should be able to start the Engine (you can let the Engine idle and put the Batter Charger on the Battery to fully charge it before you drive) and take a short drive to and test you electrical stuff and see what works.

If everthing else is working you only need to deal with the Alternator; which can be removed from the vehicle and tested for free at an auto parts store.

hi jay thanks for the reply. i dont believe i got as far as trying to start it... i may have turned the key on and then noticed the smoke from some wiring under the hood and quickly switched it off and disconnected the battery... some of the wiring insulation from the cable off the positive terminal is melted as well as the cable leading into alternator as well.

thats a very interesting theory. have you ever tried that or know of anyone who has? if so, considering i dont even have a radio in the car, how long could i expect to drive until the battery has been drained enough to where it wouldnt start the car again..?

Oh boy - I did the same thing with my '73 220D. The radio and lights worked, but I couldn't start it. Nothing burned up, though. I caught it, corrected it and it was fine.

Alternator was OK after that I think, but it did have trouble later that I corrected by having it re-wound and using a modern solid state voltage regulator.

Chances are you didn't hurt the car too bad.

Not sure why you think it is a theory.

Unless the Alternator has permanent Magnets you need the Battery to create magnetism; even with the often claimed residual magnetism.

Anyway on your Mercedes Diesel of your year once the Engine has started you no longer need the even the Battery to keep it running. You only need the Battery for the Glow Plugs and to crank the Starter.

On My Volvo Diesel the shutoff is electric. No electrical current and it shuts off. So the Mercedes has a small advantage in that.

I also have some pratical experience in a Gasser. I went on a trip and the alternator died but the Car was still running. I continued to drive to where I wanted to go wich was a small Lake and left the Engine running.

I made it about 1/2 way back before the Car started running poorly and pulled into a Gas Station and had them Charge the Battery while I got something to eat.

Started the Car with the Battery Charger hooked up as the station charger was made to do that. Continuned on my Trip which was mostly Freeway driving.

The next time I did not make it as far but made it to Moms House. Charged up the Battery again and after that made it to my House.

So that worked but I had a bad headache because after the Battery Voltage dropped to a certain point some sort of alarm like the seat belt or Key alarm would go on and stay on as long as the Engine was running.

The Car was an 81 Chevy Chevette. Small Car but had a good sized Battery. The Battery in my Van is smaller.

'theory' was the wrong word, i was just wondering if you had personal experience trying this... well as far as replacing the burnt wires/ insulation, i have looked around on the web and havent had any luck finding replacements for them.... suggestions on where i should look... ? thanks in advance.

I don't know what the Alternator on a 220D or the other wiring looks like.

Also I guess knowing what year would be helpful.

On My year and model they show the Plastic Alternator Connector parts as seperate parts you can buy. You just go to the Auto Parts store and get the proper diameter Wire you need and re-wire with that.

You should be able to pick the diamter of the Wire by looking at the old Wire. However, someone posted a Chart on amperage verses wire size/diameter. But, there should be sources on the internet of similar charts.

I don't think anyplace but a Junk Yard would have the correct wires.

I found the Year 1973 in your info.

The Alternator I found for it is a Bosch AL64X. It was listed as 35 amps. So if you are are not changing the Alternator to a higher output one or the prior owner did not do that the highest out put from the Alternator is 35 amps. So wires that can handle 35 amps would be the largest diameter ones you need to deal with with the exception of the Battery Cables and Ground Strap.

According to a chart I have 12 gauge wire will handle 41 amps, 11 gauge (which I have never seen in the autopart stores) 47 amps and 10 gauge 55 amps.

thanks very much for the info...

from the positive terminal it appears to be one wire that splits off into two as the bundle comes off the firewall... one split travels toward mid engine on the passenger side, while the other split appears to go to the alternator... would these be two separate wires needing replacing?... i included some pics in another thread i started about this topic.. i believe the thread is the one right before this one*** thanks in advance

I have no way to determine if the wires need replacement or not. Also I could not tell much from the pictures.

I would think you are in bad need of a wiring diagram and you have not mentioned that you have any sort of a Service Manual.

The Haynes type Manuals are not noted for being good but they usually have some wiring diagrams in them. There is several being sold used on eBay.

People say if you can access the Mercedes EPC you can look at a free Mercedes Manual.

If it is still being sold there is a W115/W116 Service Manual on CD from the Mercedes Classic center and there is a bunch of copies people are selling on eBay.

I have the CD Manual set for my W123 but it will not work on a computer with 64bits. It works OK on 16 and 32 bits.

Sometimes there is also the original Mercedes printed service Manuals on eBay. On My W123 the wiring diagrams are in one of the Chassis Manuals. The Engine Manual and the Chassis manual are seperate books. On the W123 there is 2 volumes of the Chassis Manual.

I don't know if this is current but this used to be the source of the official Mercedes Manuals on CD. On one side it the computer operating systems the msnuals work with.

Star Service CDs and DVDs

The free W116 site works and another site said there is some useful stuff that crosses to a W115 in it. If nothing else you can see the format of the official Mercedes service manual and how it works http://handbook.w116.org/matrix6.htm