1997 Mountaineer 5.0 -voltage drain- | Ford Explorer Forums

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1997 Mountaineer 5.0 -voltage drain-

allmyEXes

Elite Explorer
Joined
February 6, 2016
Messages
2,915
Reaction score
1,975
City, State
No. Alabama USA
Year, Model & Trim Level
1997 Blue Ex 4.0 SOHC
Callsign
KAGG 3611 (CB)
We recently purchased (2.5 mos ago) this 5.0 powered Mountaineer. It had been sitting on our path home for about 3 years. When I was able to get with the PO about it, I was able to start it with a fresh battery and what fuel that was in the tank. I drove it home from there. 1/2 mile. August 1st I picked up a budget battery from wmart. 3 weeks ago had 4 Wrangler P235-7 R15's dropped shipped from DTW ($308 delivered).
Over the past few weeks I would run the engine for about 20 minutes at a time to finish off the old gas. I then went and bought 3 galllons of 100% gasoline. (I've recently wondered if these computer controlled engines prefer fuel with 10% alcohol because I don't notice any improvement.) I also finished up what was left of the brushes in the alternator and the slip rings are spent too.
ANYWAY, back to the issue at hand. This past Saturday, I put on a good used alternator with a new reg/brush assy on the 5.0. It is charging at 14.4 and does not change. Late Monday I decided that I would start it up for a few minutes. Dead battery. Disconnected it and put the DVOM on it. 3.5 volts and climbing. I just now today charged the battery for 2 hrs. it is holding at 12.39. I thought that I would totally unhook the alternator to rule it out. It is about 70 degrees today and I can feel the back of the alternator and it feels like about 85-90 degrees. Is this normal ? And I hooked the battery up to see if it appears that the Mountaineer has a drain. Earlier I undid a hacky job of a stereo installation , so I know it's not that. Is it my used alternator ? and I did have the brushes installed in an alternator with a couple of bad diodes. Did I damage the regulator ? Or do I have a segment of the ignition switch that is malfunctioning. It has been sitting now 15 minutes with the battery hooked up and has dropped to 12.28 from 12.33. .01 volt a minute and this is with the alternator totally disconnected.
Any input or thoughts anyone ? Thanks in advance with this problem
 






1:30
It's been about 30 minutes now and the battery is holding at 12.23 volts with the cables attached and the alternator totally disconnected. I am going to disconnect the battery long enough to reconnect the alternator wires and reconnect the battery...
2:05
dropped to 11 volts in 5 minutes
2:30
checked to see if there was voltage on green/red stripe Key on or run wire. Key is off. no power was on that wire
2:35
plugged regulator connector back in. Voltage started dropping
 






It could be a bad diode in the alternator. Can you measure the amp drain between the positive battery cable and the battery terminal using your VOM? It must be pretty high to drain a battery that quickly.

The back of the alternator feeling warm with a slightly discharged battery (12.6V is considered a full charge) does, not seem that unusual. 14V from the alternator w/engine running is normal.

I think I'd remove the alternator and take it to have it tested, if just to be able to rule it out.
 






I agree. Thanks
 






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