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Dying Alternator?

JimRummy

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A couple of quick questions for you guys (who are the best let me add. I've saved at least $700 in the last year referring to you guys instead of a "mechanic".
Anyway just a couple questions. First for the back story... skip to next paragraph if'n you don't care..

A few weeks ago my truck was broken into (window smashed). They stole my Alpine 9886 Head unit, a 1200W Sony amp, 2 12' Subs with a custom box, a 2.2 farad capacitor, my iPod, my GPS, blah blah blah, the list goes on. They also ripped up my carpet, and damn near ripped my entire dash board off. The Police ended up getting the douche bag a block away, and I got everything back except the window (duh) and the iPod with some other random stuff. Since then I have installed a Viper 350 Alarm system in hopes that that eliminates the temptation for stealing my hard-earned stuff.

Since all of that the alternator seems to be taking a dump on me. The Electrical gauge (and head lights and such dim) bobs around during idle, and sometimes when stopped at a light. Now today after driving about 6 miles (enough to stabilize in my opinion) it was on the south end of the dial. I let it idle instead of killing the engine when I got to my destination, and it seemed to go "normal", and stay there until I returned home. It has bee doing this for a few weeks now. I am concerned because I just had a new baby, and I had little to no funds for the truck to begin with. I was just curious if the fact that they ripped everything out could of caused a problem. There were a lot of stereo, and power, and just a lot of live wires grounding to God knows what before I had a chance to disconnect the battery. I have since fixed everything, but now I am having the alternator issue. I do have a lot of electronics sucking juice, but I do have a Optima yellow top, and a 2.2 farad capacitor, so I was under the impression that I shouldn't be having these problems...
ALSO, are these high amp alternators a reasonable choice? I've seen 250 amp, but that seem overkill.. Thoughts?

On a side note I had to replace my thermostat a month back and had to use a cheap-o murray one (O'reilly, autozone, and pepboys had no motorcraft, or good ones). It has an opening temp of 190. It seems like over half the time the needle gets past the L on NORMAL before it opens, and drops to C or normal. I also notice that even after a short drive (5-10 mile round trip) it is filling up the coolant reservoir. Is that normal? This truck has had cooling issues(or lack thereof) for about 5 years now.
Thoughts?

1993 4.0 V6 AT 105k
 


adsm08

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You need to bust out the volt meter and actually take a reading at the battery with everything off and the engine running before any determinations about the alternator can be made.

And don't take it off and take it to the store to get tested. Those things pass it if it makes 12V. 12 volts is not a good alternator, 14.5 volts is a good alternator.
 

Frank The Tank

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I kind of think you have a dead short wire somewhere. The easiest way to test alternator is to start it. Unhook the battery then turn on the headlights. If it acts like usual it's probably a wiring issue from the thief if it dies then it's probably the alternator.

The cheapest high amp alternator you can get on these trucks is a direct bolt on from a ford diesel 6.0 or 6.4? Maybe someone can pitch in on whack it is.
 

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The easiest way to test alternator is to start it. Unhook the battery then turn on the headlights.
Quickest way to kill an alternator know to man!:icon_surprised:
 

Frank The Tank

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I didn't say fill it full of gas and drive it for 6 hours. Lol. If your alternator is hooked to the battery it will cycle on and off. Pulling the battery will just keep it on full load for a second lol

V I don't believe you Adam ;)

My ranger is 42 years old though....

Sounds like you need to get a voltmeter and poke around. I still think it's shorting though with your trucks wiring history.
 
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adsm08

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It's also bad for the computer and will work on as little as 11.5 volts which is still discharging the battery.

The long and short of it is that that test has been out dated and inaccurate for almost 30 years.
 

JimRummy

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Yeah, see I was thinking it was a short somewhere, but I know that I soldered and shrink tubed any connected that was broken.. It had done this to a certain extent (small bobs of the needle, much less frequently. Today was the first time the needle went towards the 8 mark), so I am not sure what to make of it. The carpet is running right on top of the grounding wire for the capacitor and amp.. could that make a difference..
ALSO it does this regardless of whether or not the stereo, amps and such are running.
Like if I start it without the face plate connected it does the same thing, and when the needle bobs it moves a solid 1/4', so its a decent drain, whatever it is....
 

JimRummy

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So since all of this ( a month ago) it has gotten worse. Now when I start it up, the needle is between the N in NORMAL and the 8V mark. I drove it for about 15 miles today just to stretch its legs, and it didn't fill me with confidence. At no point during the drive (even with 3/4 throttle) the needle didn't get even to the N in normal. After I stopped, I was close to the person in front of me, (had to parallel park) so I restarted the truck, and it barely started. Was acting like a 7/8 empty battery.
So the question is before I start my diagnostics (have to go to my parents 55 miles away to be able to work on it) is the electrical gauge measuring the voltage between the alternator to engine, or alternator to battery, or am I completely off base.
Since the battery/alternator has been taking a dump on me, I've noticed some ticking/clicking/whatever for a few seconds after starting....
Thoughts?

Thanks in advance.
 

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See that fuse? Check that.

You'll need a voltmeter to do any real testing.
Check volts at battery posts, then again with engine running.
Should be a couple volts more (about 13.8-14.3) with the engine running, even at idle.

If you can drive it to an auto parts store, most will do a diagnosis for free.
 

JimRummy

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Ok cool, i will check that tomorrow. I cant do squat at my apartment, so i have to go to my parents to look and address whatever it is. Is a 65 mile drive risky while its like this (needle almost at the 8V mark)?
 

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The clicking is likely relays getting screwy from not enough power.

A 65 mile trip? You won't make it if you genuinely only have 8V available. Do a real test before driving anywhere.
 

JimRummy

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So Adsm was right on point. I got 30 miles before it died on me. Had it towed to a close pep boys and after testing my yellow top battery is bad. Got a free replacement since it was within the 3 year warranty. New battery installed and the needle is in front of the n on normal after a few miles.. alternator for sure toast?
 

adsm08

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I'd sure be checking it's output after that. Running with a stone dead battery can fry all sorts of things and puts an awful load on the alternator and it's wiring.

Heard a story from my shop foreman once, he gave a guy a jump from a stone dead battery, told the guy to get a new one before he fried the alternator. The guy told him it'd be ok, he'd just drive around a bit to charge the battery up. 15 minutes later Bob passed the truck on the side of the road, engine bay in flames.
 

JimRummy

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Wow, gnarly.
After putting in the new battery, and getting stronger voltage with the truck off, I got a new alternator. Everything seems good, but the gauge seems either very sensitive , or very accurate , because it moves allot more then it ever did before with the stock alternator (before the issues started). Four example when I start it is at the n o, when the rpms rise its dead center o r m and drop to the n o at a stop , but then goes back to center when I get going. Seems like how it should be, I'm just not used to it showing exactly what's going on. Thoughts ?
 

adsm08

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If everything else works, don't worry about what the gauge does.
 

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