Hey guys!

Ill make this as short and sweet as possible, since Ive already posted in my local online forum here -----> SAOffroad post

I have an 87 XJ.
Went mudding on Friday in some pretty heavy stuff.

: First the fuse for the taillights/interior gauges blew, replaced it. Works.
: On the drive home, noticed the battery was low and the lights were dim.
: Got home, battery just about died. Turned it off and on a few times, it finally died.
: After jumping it today, it runs perfect for a few minutes, then dies after a few stutters. It also makes a 'pop' or 'backfire' when I let off the throttle.
: I checked the IAC, TPS, intake seems to have not gotten anything in it. The plugs and distributor seem to be okay.
: The only thing that is obvious thats not working properly is the Alternator.

Question, can a dead Alternator cause the engine to hesitate and die after a few minutes? Remember its got no juice since the Alternator is dead, and the battery that just got jumped only has a tiny amount of juice. Im going to try to clean it as carefull as I can now.

And the reason i dont think its anything with the fuel/air is because it runs perfect for almost 3 minutes or so, but after removing the jumper cables and the battery level starts to drop fast, it begins to hesitate and stutter, eventually dying.

Any ideas? Would a failing battery (because of no alternator juice being pumped to it) cause the engine to just die..or would it stutter and affect the throttling up until it finally gives?

 

Yes the alt is not properly charging the battery! replace the alt, have the battery properly charged to 100% and then see how things run.

basically the battery is running the car and as the voltage drops it starts messing with stuff and not giving the proper power supplies

 

i agree with 96 replace ur alt and ur problems should be over... till the next mud bog atleast

 

x3 what 96 said. also if you are going to play in the mud frequently search on how to raise your alternator. people have had success raising it

 

thanks guys!
Im currently about to drop it and clean her up..see if i can get it working instead of droppin the cash on a new one or picking one up from the local PnP...

It makes sense...and yeah, Ill be more careful next time..it was a spur of the moment decision with a bunch of other rigs watching..I couldnt NOT do it! besides, my jeep was impressive, they have 4wd trucks that couldnt make it look that easy haha.. course they are up and driving the streets right now... o_O

 

Did you check the charging system with a multimeter to see if it's actually a failed battery rather than an bad alternator? That can do the same thing. And if you bounced it around hard enough, you certainly could have shorted out a cell.

 

Sounds like the alternator for sure. Replace it and you should be good... Until the battery croaks from being drained down repeatedly. I'd invest in a battery, too, just to play it safe... (I speak from many years of mechanic work...)

 

well i should go have it checked with a multimeter (guess i can buy one..but i cant find mine!)....

but I loosened all the bolts and the belt to take off the Alternator, and i broke a few 13mm sockets trying to get the first bolt off!!

so now i get to go buy some stronger sockets..Id use an impact gun but its only usable on the rig that wont run lol...(OBA system).

 

charge u batt and start the jeep after you got her running pull the positive off ur battery if it dies immediatly ur alt is shot

 

okay, been busy as hell and finally got around to the jeep in the garage.
damn thing wont come off! I have the power steering assembly loose (though not much to really take the belt off..what gives?) and the alternator bolts are all out..2 up top in the back and 2 in the front on the bracket (that has 4 total, but only 2 for the alternator).

i cant remove this damn thing! Im pretty sure its the alt since the thing is cacked with mudd, and it does spin by hand and nothing comes out anymore, but i bet its internally shot

 

I would not do that. I tried it on my Chevelle and fried the ECU chip. The alternator can put out voltage spikes, and the battery is the buffer that levels them out.

Charge the battery to 100% and see if it runs good. If it does and dies within a few minutes, you will need both a battery and alternator. If it runs a while, you probably just need an alternator.

 

got her out!!
was actually quite simple, once you know what you're trying to do..
Im going to make a write up when i can, because this forum as many times as it claims, does not seem to have an "alternator removal" writeup...Ive searched the 'write up' pages, all 5, one by one. Replacing the serpentine belt is also a sinch, and not as difficult as it sounds, just tight in some areas. If you have a direct link to a good writeup, shoot it my way to correct me

The alt definitely has some major 'congestion' inside the rear mostly, where the charge is stored...the bearings seem good, as it spins great with very minimal to no sound at all. I pulled a good amount of mud and small twigs and stuff out of the alt, so Im guessing it was spinning, but not charging which means the copper dealyo (my term lol) is probably shot..maybe a rebuild.

But the alt requires some special starshaped/torque sockets to remove the outter casing, so i might just go find a pick n pull replacement...now..what years can i use the same mounting locations on and get the best/upgraded ampage?

 

The "star shaped" sockets are Torx sockets. And alternators don't store charge, that's the batteries job. Thought ya ought ta know. LOL

 

The voltage regulator distributes the power the alternator creates, and it controls the output of power to the battery(it does store voltage). The rectifier bridge converts the power from AC output to DC, while the brushes and slip rings help conduct current to the rotor field winding, or wire field.