Alternator / battery voltage problem

[bogger69]

So I went to mclean on Sunday and on my way home my battery gauge went from 14 perfect to 9 all of a sudden  . A couple people have said it's the alternator but I dont think it is.

Ok so maybe im just crazy but my dads mechanic friend also said its the alternator but I don't think it is, Here is why:

- I hooked up a battery to mine that had a full charge, now my XJ has a bunch of gauges and the battery one read 11.5-12 volts with a fresh battery hooked up to the one in it, however, after like 5 min it sudendly droped to 9 which is really odd.

- Also I had this problem ( where it would start at 11.5-12 vold then drop to 9 ) like a week ago and after playing around with the ground it went back to 14 and i didnt have a problem until we went to mclean....

I don't want to buy a new alternator for $250-300 if I dont need one because I have $0 to spend so what else could it be?!?

[FiEND]

what year and model and motor type in the vehicle?

[dubbleJs]

XJ's always have alternators problems...(I think this is on an XJ?) It sits so low on the motor and get mud and junk in the brushes and stops working. Ive been through a few alternators over the years...but I just keep replacing them with $20 PnP specials and don't worry about it. If you can't find another problem and want to try another alternator...I'd suggest heading to the junkyard.

 

[bogger69]

It's an XJ 1999 I6, but idk u sure maybe if i give the brushes a good clean? haha? I dont live in calgary and i cant gt to pick n pull and i need my jeep to drive from my farm to school lol

[raf2379]

to make you feel better i'm having same problems, but I didn't have time to troubleshoot the problem before i left for work. the alternator problem is suspecious to me too, i'll look into it when I get back home. could be brushes, loose connections, but looking at the schematic, its a simple charging sytem, meaning it does not have any shutdown devices such at a battery temperature sensor which would shut down your alternator if overtemperature or anything else that would tell the computer to stop charging.

[Tyn Pow]

So I went to mclean on Sunday and on my way home my battery gauge went from 14 perfect to 9 all of a sudden  . A couple people have said it's the alternator but I dont think it is.

Ok so maybe im just crazy but my dads mechanic friend also said its the alternator but I don't think it is, Here is why:

- I hooked up a battery to mine that had a full charge, now my XJ has a bunch of gauges and the battery one read 11.5-12 volts with a fresh battery hooked up to the one in it, however, after like 5 min it sudendly droped to 9 which is really odd.

- Also I had this problem ( where it would start at 11.5-12 vold then drop to 9 ) like a week ago and after playing around with the ground it went back to 14 and i didnt have a problem until we went to mclean....

I don't want to buy a new alternator for $250-300 if I dont need one because I have $0 to spend so what else could it be?!?

I had pretty much the same problem two weeks ago after I went thru a suprisingly deep hole.  Halfway back to Calgary the voltmeter starting dropping to 9 and by the time I was in Calgary it was at 0.  New alternator fixed that.

Also, you can get (or make) a new alternator mount that moves your alternator to your A/C compressor location, up high and dry. 

[Bnine]

Thats a common alternator issue. The gauge is up because of the battery. The battery is supplying 12 volts to the system while it still has a good charge. Once the battery starts to drop due to lack of charge from the bad alternator, then gauge will drop accordingly.

Try washing out your alternator, and then re installing. It might still work.

Then look around Naxja or somewhere for tips on how to keep the XJ alternator alive.

[JENSSEN]

hose the aternator, hit it with a hammer a few times,... repeat till it stays steady at 12V the lube the bearing,.. continue on

[bogger69]

So how do I take the alternator out is it hard?

[raf2379]

i replaced mine couple years ago i think, if i remember correctlt I removed it fron the bottom. first disconect the batt, release you tentioner pully and remove the serpentine belt, disconect wiring to alternator, remove bolts for the alternator, remove oil filter i think its in the way i cant remember... (or maybe thats on my other vechicle ) and you should be able to remove it from the bottom. like i said its been a while since i removed it maybe some one else thats done it more recently can correct me 

[Tyn Pow]

^^^ This pretty much, except you don't have to take the belt completely off, as it annoying to get back on and you don't need to take the oil filter off.  And it does help to take the battery right out so you can access the top alternator bolt.
It's a tight fit to come out the bottom but if you twist it just right it'll come out. 

[WagoneerXJ]

on my 98 xj when the alternator quit, I fished it out the top. Removed the belt, wiring and mounting bolts for alternator, then yanked the battery and the battery tray. Worked good for me.

[vantagetes]

So how do I take the alternator out is it hard?

No problem! (It's the getting it back in after this method that is the trick)

[bogger69]

So I took it out tonight and am gonna buy a nice new one tomorrow however, when i took the alternator our i turned the wheel a couple times and it spinds fine usually if its screwed it squeaks or has trouble turning? But it seemed to be fine :S that would suck if it was a whole other problem.

[Immortal]

Your brushes are pooched.... or really dirty. The altenator will spin fine, but your brushes aren't making contact. Hmmm... Check the brushes, maybe they are just worn out. that would be a super cheap fix.