BIG problem.. need help

[inoki]

My car recently wouldn't start. So I had it boosted, took it to the gas station, shut it off for gas.... wouldnt start, so I got it boosted again. Shjut it off at work, and it wouldnt start again, so I had it towed to a shop... they "cleaned the cable"... put new ends on, charged me 63 bucks, and when I got the car home, and went to use it 4 hours later it again wouldn't start. So I got another boost took it to another mechanic, he put a new battery in, so this morning/ I go to start it, still wont start. He said he tested the alternator, and that wasn't it, doesn anyone have any ideas as to what my problem could be?

Thanks for any help....

[quaddriver]

Originally Posted by inoki

My car recently wouldn't start. So I had it boosted, took it to the gas station, shut it off for gas.... wouldnt start, so I got it boosted again. Shjut it off at work, and it wouldnt start again, so I had it towed to a shop... they "cleaned the cable"... put new ends on, charged me 63 bucks, and when I got the car home, and went to use it 4 hours later it again wouldn't start. So I got another boost took it to another mechanic, he put a new battery in, so this morning/ I go to start it, still wont start. He said he tested the alternator, and that wasn't it, doesn anyone have any ideas as to what my problem could be?

Thanks for any help....

Year/make/model would be more help, but, if you put in a new battery and it drained overnight, either the planets aligned such that you got a bad battery or......

a drained battery means something drained it (duh! right?)

First check for parastitic current - place an ammeter in line with the battery + terminal with key OFF and all doors closed....you should see a few mA bleed due to the ecm, clock - if not, someone is shorted or an 'off' switch aint offin

then, leaving the ammeter hooked up, leave and come back later - I suspect you will see 1-5A flowing (oh btw- use the 10A setting on the meter so you dont torch it) what I *suspect* is happening is one or more of the rectifier diodes are breaking down and when car sits and saturation level is reached, the junction actually flows current in reverse, thru the windings, drawing the 1-2 amps (I have seen as high as 10) - does not take too many hours before the battery is kaput.

this type of failure is insidious as it does not show up on an alterator 'machine', you must disassemble the alt and test the PIV of the trio separately (typically the trio diodes will resist 50v in reverse before they pop). the fix is of course a new trio, and since you are in there, regulator and brushes cant hurt, and for that matter bearings. In other words, a rebuild.

[CraigFL]

What you don't say is how the car didn't start.....

1. Did it crank normally but just didn't fire?
2. Did it crank normally, fired, but didn't actually run?
3. Did it crank normally, fired, run for a second but wouldn't stay running?
4. Did it crank slow & die?
5. Did it just click?

All the above signify different potential problems. Trying to start a car with any the above could lead to a dead battery quickly in the cold weather. Using a good, prewarmed battery (or jump) could cover up the actual problem. Putting new ends on the battery cables just rules out them being the problem. Looking for current flowing from the battery while the car is off would be the place to start for #4 or #5 above.