Weird????

[smokinporsche]

I have a weird issue and was wondering if anyone else has heard of this. My 7.3 decided to start draining batteries. When you recharge the batteries the truck cranks just fine, also I replaced the alt and new batteries and same thing. If it sets for a few days dead! The alternator is putting out 14 volts so that’s good, but one thing I noticed is when you connect the grounds on the battery the alternator becomes magnetized, is this normal? I looked at some of the posts about dead battery and nothing was posted to fit my issue

 

[Exekiel69]

How old are the battery wires? is there any cracks in them? How old are the batteries? If it where Me I would check all the wires and connections bc that is provably where the problem is.

 

[icanfixall]

The diode bridge in the alternater is bad. When the ignition is off the bridge is supposed to open and stop the direct drain from the batteries. Look at it this way. When the motor is running the alt is pushing power into the batteries. When its turned off you need some way to open this circut. Thats part of what the diode bridge does. It also changes 120 volts ac over to 12 volts dc hence the name ALTernater.

 

[tonkadoctor]

The diode bridge in the alternater is bad. When the ignition is off the bridge is supposed to open and stop the direct drain from the batteries. Look at it this way. When the motor is running the alt is pushing power into the batteries. When its turned off you need some way to open this circut. Thats part of what the diode bridge does. It also changes 120 volts ac over to 12 volts dc hence the name ALTernater.

He nailed it, it's a common problem, Alternator can put out the correct voltage and still be bad. Take it in and get it tested.

IIRC the batteries that were in it were only about 2 years old, got them at Sams Club, I put them in right after I originally bought that truck, think I left the receipt in the glove box.

 

[smokinporsche]

Okay did some more investigating, when I disconnect the lead on the right side of the starter solenoid the one with the smaller red wire from the battery the drain is gone? Is this a bad solenoid staying open?

 

[smokinporsche]

The diode bridge in the alternater is bad. When the ignition is off the bridge is supposed to open and stop the direct drain from the batteries. Look at it this way. When the motor is running the alt is pushing power into the batteries. When its turned off you need some way to open this circut. Thats part of what the diode bridge does. It also changes 120 volts ac over to 12 volts dc hence the name ALTernater.

The batteries are brand new, and the minute I connect the grounds the alternator becomes an instant magnet! When I disconnect the small red lead going to the right side of the starter solenoid the alternator is no longer magnetized!

 

[smokinporsche]

He nailed it, it's a common problem, Alternator can put out the correct voltage and still be bad. Take it in and get it tested.

IIRC the batteries that were in it were only about 2 years old, got them at Sams Club, I put them in right after I originally bought that truck, think I left the receipt in the glove box.

Looks like your sporting around in an even newer Ford! Looks awesome! I did find the receipt but Sams is a good drive from here so I just went to the local Autozone and bought new ones since the ones you put in had maybe one more year left.

 

[smokinporsche]

How old are the battery wires? is there any cracks in them? How old are the batteries? If it where Me I would check all the wires and connections bc that is provably where the problem is.

These look like factory wires, I did check and everything looks ok, I did send an email to the guy in AZ for new wires waiting for a reply. Thanks.

 

[tonkadoctor]

Yep, was getting concerned about the engine in the 2000 and it in when I played a game of lets make a deal at the stealership and won .

I really can't help you much on the electronomo stuff other than the basics. Really think you should get the alternator tested for a bad diode to rule that out and then go from there.

Don't know what the wiring is supposed to be like on the solenoid but hopefully one of the experts here will chime in soon.

 

[smokinporsche]

Yep, was getting concerned about the engine in the 2000 and it in when I played a game of lets make a deal at the stealership and won .

I really can't help you much on the electronomo stuff other than the basics. Really think you should get the alternator tested for a bad diode to rule that out and then go from there.

Don't know what the wiring is supposed to be like on the solenoid but hopefully one of the experts here will chime in soon.

Great thanks, this is my second ALT. and both have been tested and purchased at Autozone and they were both good? I will let you know what I find. Also going tomorrow and having a .373 gear set with a posi put in her. The 308's are just too high! I need more pulling power. I was going to go ahead and put in .410 but I think one step down is not too much and adding the turbo and posi will make up the difference

 

[tonkadoctor]

Great thanks, this is my second ALT. and both have been tested and purchased at Autozone and they were both good? I will let you know what I find. Also going tomorrow and having a .373 gear set with a posi put in her. The 308's are just too high! I need more pulling power. I was going to go ahead and put in .410 but I think one step down is not too much and adding the turbo and posi will make up the difference

When I wrenched for Pep Boys years ago I saw new alternators come back DOA in a day on several occasions. If it tests good, no reason to replace it, just make sure the yahoo behind the counter knows how to work the machine and test them properly.

I think the 3.73 will be a good choice. The speedometer gear on the cable for the 4.10s was a black 20 tooth, a 19 tooth pink p/n C0DZ-17271-B should be the match for the 3.73 to calibrate your speedo.

 

[Agnem]

Is your alternator warm when the engine is cold? If so, your field may be staying engergized. This would possibly be a problem with the wiring, or again the alternator.

 

[haywire]

what year is your truck,does it have the internally regulated alternator? if not feel the regulator. if the problem persists, try disconecting the plug on the alt. with the two wires coming out when you park it for the night and see if it still drains the batteries.

 

[smokinporsche]

Is your alternator warm when the engine is cold? If so, your field may be staying engergized. This would possibly be a problem with the wiring, or again the alternator.

Yes very warm - hot really after the truck has run a few min. I took the first new alternator back to Autozone and they tested it and it tested good, but they gave me a new one anyway and I had them test it before I left and it's doing the same thing which leads me to think it is something else

I just installed a new banks sidewinder turbo and new glow plugs, and relocated the relay with their kit, but that all works just fine, do you think the glow plug relay is eaten my batteries for lunch?

 

[smokinporsche]

what year is your truck,does it have the internally regulated alternator? if not feel the regulator. if the problem persists, try disconecting the plug on the alt. with the two wires coming out when you park it for the night and see if it still drains the batteries.

1990 F-350, I think it has it built in? How do you tell?