Post haste alternator work around

fordman · Post by **fordman** » Mon Dec 13, 2010 6:52 pm

my alternator went out of my subaru tonight. one of the diodes went bad. and i cant get another one until tomorrow. but my wife needs the car for work tomorrow, is there any kind of rigging i can do to get around this for 24 hours? maybe i can strip something out of my ford alts to make it work. any ideas on what to do in this situation?

fordman · Post by **fordman** » Mon Dec 13, 2010 8:11 pm

wait a minute. the guy at oriellys said the alternator had a bad didoe. we got the car home not using any lights or other electrical equipment. i used the hand brake to slow the car. anyway. so it runs for abotu an hour now. i go tout and test the battery and i have 12 volts. the headlights work and the car will restart itself now. if the didoe is bad is is trying to go bad or is it letting it overcharge now instead? the car got hot sittign there and lost all the antifreeze too. so now the car is sitting waiting to cool off before i cna refill the antifreeze. so whats with the didoe supposedly? is it bad and not working. only working part time? or is it over charging with a bad diode?

Mancar1 · Post by **Mancar1** » Tue Dec 14, 2010 9:51 am

If a diode is bad won't the current find an alternate route to the battery? I know a diode/heatsink allows the current to flow in one direction only. It also helps protect electronic stuff from reverse flow. I think with a bad diode you can still get a charge, It may start and drive, but I wouldn't drive the car until I replaced the part in question. I'm afraid my limited knowledge wasn't much help.

Racer Z · Post by **Racer Z** » Tue Dec 14, 2010 10:40 am

The coil and ignition don't consume a lot of electricity. The car will run for quite some time as a total loss. Starting the car, headlamps and all the other stuff consumes tons of current and will drain the battery quick.

The diode: A diode is a one-way-valve for electricity. That means ecletricity can flow one way past the diode but not the other. I'm not sure what the diode is used for in the alternator, but I do know of two possibilities.

1. To keep the battery from trying to spin the alternator like a motor.
- a. Not to likely. Turning the ignition switch off disconnects the battery.

2. The alternator creates "alternating current" as in AC. The battery and rest of car/truck work with DC (direct current). To convert AC to DC it needs to be rectified. The rectifier is made with four diodes.

If one of the four diodes goes out you may be getting some electricity from the alternator and partially charging the battery. The rectifier and the voltage regulator are built into the alternator now, unlike our Bumps. Get a rebuilt alternator and be done with it.

Mancar1 · Post by **Mancar1** » Tue Dec 14, 2010 11:06 am

The diode plays a part in converting AC to DC current. Oops already been said.

I wouldn't drive like is. As I mentioned it may damage some electronics.

Racer Z · Post by **Racer Z** » Tue Dec 14, 2010 11:38 am

Mancar1 wrote:The diode plays a part in converting AC to DC current. Oops already been said. I wouldn't drive like is. As I mentioned it may damage some electronics.

I agree that you should not drive it until you fix it.

I'm pretty sure (but not 100%) that it gets rectified, then regulated. If the regulator is still good, it's going to be hard to over charge things. Although, the AC might wipe the regulator out and then over volt the newer computerized system. Scary stuff.

Hawkrod · Post by **Hawkrod** » Tue Dec 14, 2010 12:18 pm

Racer Z wrote:The coil and ignition don't consume a lot of electricity. The car will run for quite some time as a total loss. Starting the car, headlamps and all the other stuff consumes tons of current and will drain the battery quick.

The diode: A diode is a one-way-valve for electricity. That means ecletricity can flow one way past the diode but not the other. I'm not sure what the diode is used for in the alternator, but I do know of two possibilities.

1. To keep the battery from trying to spin the alternator like a motor.
a. Not to likely. Turning the ignition switch off disconnects the battery.

2. The alternator creates "alternating current" as in AC. The battery and rest of car/truck work with DC (direct current). To convert AC to DC it needs to be rectified. The rectifier is made with four diodes.
If one of the four diodes goes out you may be getting some electricity from the alternator and partially charging the battery. The rectifier and the voltage regulator are built into the alternator now, unlike our Bumps. Get a rebuilt alternator and be done with it.

The diode does rectify power flow, without it voltage that is created is sucked back in and countered on the next wave (simplified explanation). One very major point though is that the ignition switch does not disconect the alternator and a bad diode drains the battery when the car is not running. It is very important to understand that the battery is always live to the alternator and the diodes only allow power flow from the alternator to the battery so a bad one allows the reverse when the alternator is not charging. You can usually drive with a bad diode it is just that you will have greatly reduced power output and if you do not disconnect the battery it will drain when the key is off. It is also important to note that the ignition switch is not connected to the alternator in any way. The ignition switch is connected to the voltage regulator and that determines how much power the alternator produces. Finally, it is important to note that if you have an older carbed car you can drive with a bad diode but a newer FI car requires precisely regulated power and reduced output can cause lots of problems. Hawkrod

fordman · Post by **fordman** » Tue Dec 14, 2010 1:27 pm

ok so that is whats going on. the battery is draining as i type. i couldnt get a alternator last night. but since the car charged up i told my wife to use it to go to work. we had no choice. i know i can get an alternator today. or have mine rebuilt later in the week when my wife is off of work.

Mancar1 · Post by **Mancar1** » Tue Dec 14, 2010 4:13 pm

Got my fingers and toes crossed for you and your wife on this fordman. I'm sure all will work out on her car.

fordman · Post by **fordman** » Tue Dec 14, 2010 8:13 pm

she didnt have any trouble with it today. and i forgot to go to the alternator place and get a rebuild kit for it. i guess i will do that tomorrow. i'm not working on that dodge again until thursday now.

fordman · Post by **fordman** » Sat Dec 18, 2010 1:13 am

thanks to everyone. i ordered a new rectifier and installed it today. it was pretty easy. no soldering it all bolted together. the only thing i did wrong was left the regulator botls loose. so the first time it didnt work. but once i took it back apart it worked fine. instead of buying a new alt @120.00 i spent only 30.00.

BRUTUS_T_HOG · Post by **BRUTUS_T_HOG** » Sat Dec 18, 2010 3:38 am

. im 20 and have only rebuilt 1 alternator in my life.

i would have replaced the whole thing.

as for your COOLANT loss.. get under the car and check the head gaskets.. those boxer engines always like to leak externally from the head gasket. i don't know what year you have so i can't really say much more.. i know the older ones have a bypass hose on top of the engine under the a/c compressor that can be hard to trace

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Post haste alternator work around

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