I have a '86 F-250 that drains the battery while running. It has sat for a while but recently had a rebuilt engine put in. Any suggestions will help.

 

That's weird.
I would take the battery & the alternator to a auto parts store and have them checked (for free) first.
You can probably take the whole truck and they can do it on the vehicle.
Once you know they are both good ,come back and we can figure out the problem.

 

i just worked on an 86 302 lincoln that did this very same thing. the problem was in the alt. changed the regulator at the same time just to be on the safe side

 

my ford 1998 f150 kills the battery when parked for 2 days
is there anything anyone can think of besides the alternator
battery i checked the cells all ok

 

Click the hyperlink to my gallery on the left.

Scroll down to the link's to things.

Look for *How Detect a Short*

 

Hey jeffm, I didn't click on mil1ion's hyperlink, so this may have already been revealed there. It is possible for the starter solenoid (relay on fender wall) to drain the battery if it's been damaged. The act of over-torqueing the terminals on the solenoid can cause things to work loose, causing shorts inside. You wouldn't know at first, because it may simply send current to the spark coil, which would only be a 4 or 5 amp draw. But over the course of a day or two, the battery bites the dust. The way that I discovered this was to pull one of the battery terminals off the battery, and connect an ampmeter between the cable terminal & battery terminal. It is normal to see a drain of 2 or 3 MILLIAMPS, but if you see more than that, it is the problem. You can start wiggling wires & connections, especially on the solenoid. If you wiggle the correct (malfunctioning) connection, the current draw will suddenly fluxuate wildly, sometimes hitting 4 or 5 amps if it is the above-mentioned problem. Obviously the vehicle isn't running when you do this, nor would you want to turn on any high drain items (like the STARTER). Do you or a friend have a multimeter, with a 10 amp capacity??

 

TATYQ,

Yes, The solenoid can develop a short within itself to ground.

 

guys
today i disconned negative battery put test lite in between and it lit so i pulled alternator wire lite went out
it ment bad diodes
someone in here said how to check it that way
i thank him
i should have remembered it as i was a shop owner 15 years ago
160 bucks for a alternator,ill have to drink less beer this week

 

What did you get a dual-pulley 70 or 80 amp?

 

i think it's 60 amp
it has a surpintine belt
parts here in new mexico cost big
i installed it just now
jeff

 

Hey Zccornett, have you had your stuff tested yet?? My guess is that it is just the typical stuff ... failing diodes in the alt, or failing regulator. Do you have an INTERNAL or EXTERNAL regulator??

 

He mentioned that it was the diodes, & now his wallet is lighter because he just replaced the alternator.