Alternator issue on my 96 Cobra(NEED HELP)

[greenscobie86]

Hey all,

Writing this post in aggravation(sort of :BangHead

So I've gone through literally 4 alternators(rebuilt ones) in the course of 4 months...

I've chalked the first couple up to bad rebuilds but now I'm suspecting that the car is to blame for frying these things lol.

It seems that the voltage regulators fail and the alternator stops charging after about 2~3000 miles of use.

I'm pretty much at a loss here:

All the wiring looks great.
The battery Isn't shorted and is in good shape.(I've had it tested under load/no load and CCA on a professional tester)
The car is literally stock electrics-wise. No big aftermarket radios or alarm systems. The only non stock stuff is the LED's in the cluster...

One thing to note, the tach needle in my car acts really funky at times. I'll explain:

Most of the time it simply doesn't respond and sits at 0 RPM.
Sometimes it likes to make a complete 360deg revolution and gets pegged at the opposite end of the tach.
Sometimes(rarely) it actually works good.

My knowledge of the tach is that it may be tied to the voltage regulator to receive the RPM signal, is this true?

Finally has anyone had a similar problem on a 96Cobra(or any other stang for that matter) that can provide some input?

This swapping alternators is starting to wear me down, sure I can change them in 10 minutes flat now, but my mechanic is growing tired of getting me warrantied replacements...

Thanks in advance!!!

 

[ttocs]

you have some gremlins in there for sure but not sore what to tell you to check first. I Would start simple and make sure all the stock grounds are good. I was suprised to find the one by the battery was loose enough I could wiggle it around with my hand and the hole was actually stripped out. I would also check the stock ground from the motor to the chassis, maybe it is seeking a better ground through the electronics. Basically lets start simple and then work our way into the bigger stuff...

 

[greenscobie86]

Great thanks for the aid!

I suck at electronics... But I do a have a professional multimeter at my disposal...
Should I be checking continuity? If so how would I do that or what is the best way to go about it?

If someone has some ground/wiring schematics for these cars I would probably give you a hug

 

[THREEOTWO04]

Same exact issue im having right now. 5 alts, 2 batteries. Im getting sick and tired of all this. If i were you replace the grounds, then check the wire from the alt to the battery. Seemed to help for awhile

 

[greenscobie86]

^
I feel your pain man... but it gives me salvation that I'm not alone and someone else has seen this issue before... i will check the cables. I don't want to suspect rust because my car was a FL car all its life... Maybe some cracked/frayed insulation could be the cause of all this...

I really hope I can figure this deal out...

 

[greenscobie86]

I've managed to find the schematics for the alternator wiring.

Wondering where to start.

All the wires out of the alt pretty much go to the computer or the battery...

Would it be a good idea to start troubleshooting on the interior side of the harness(ECM to cluster) or on the engine compartment side of things(Main harness to Alt/Battery/Grounds?)

Just looking for a little more input before I dig into this with my electrical "noobishness."

 

[Venomous96Cobra]

I would start in the engine compartment! and I would also def! check my grounds

 

[greenscobie86]

Yup, grounds are first on the list...

It's funny actually, I bought my Cobra from FL also, never thought I'd be running into electrical problems with it lol...

 

[greenscobie86]

UPDATE:

The problem still persists.

The shop I usually go to didn't have a free lift so I could start checking the grounds...

I tried a shortcut and ran a wire directly from the neg. battery cable to the alternator(via amounting bolt)

The rev counter seems to still stick in the dead position most of the time... So I guess my attempt to emulate the engine ground didn't work?

New observation, as the car hits a bump the tach sometimes comes back to life...

 

[CanaryGT]

Ohhhhh Someting is loose.... I think...

 

[ttocs]

agreed, sounds like a bad connection if it comes and goes.

Do you know how to do technical taps?

 

[greenscobie86]

LOL, real funny....

Checked over the alt fuse and fusible links. All is well...

Gonna trace the wiring and start looking for plugs that might be loose. I'll also tear out the cluster and clen the connectors with a pencil eraser cuz' that's easy

After that I'm up the creek.

 

[greenscobie86]

UPDATE:

Had the car diagnosed by an electrician at the cost of $40 this past Saturday.

Verdict is: I am getting some very shitty rebuilt alternators.

The tech went and checked load/no load output and it was great at 13.9~13.8 volts.
He also went ahead and checked for continuity across all the cables/terminal and plugs.

He also did some other testing and got all the resistance reading for the underhood wires.

His advice to me was to get an OEM Motorcraft alternator that has a "good" voltage reg. and not the Chinese knockoff crap that they put in the $100 rebuilds that I got.

Cluster is still dead most of the time, the electrician noted that this is likely a bad cluster(such as internal electronics) so I'll either find another used cluster or just live with it.

So I guess my problem is semi solved. I now know the wiring in my car is fine, but I will still need to buy a genuine alternator once another one of these shitty rebuilt ones fails on me...

Let this thread be a lesson to all, buy it nice or buy it twice... :BangHead:

 

[l_____l]

UPDATE:

Had the car diagnosed by an electrician at the cost of $40 this past Saturday.

Verdict is: I am getting some very shitty rebuilt alternators.

The tech went and checked load/no load output and it was great at 13.9~13.8 volts.
He also went ahead and checked for continuity across all the cables/terminal and plugs.

He also did some other testing and got all the resistance reading for the underhood wires.

His advice to me was to get an OEM Motorcraft alternator that has a "good" voltage reg. and not the Chinese knockoff crap that they put in the $100 rebuilds that I got.

Cluster is still dead most of the time, the electrician noted that this is likely a bad cluster(such as internal electronics) so I'll either find another used cluster or just live with it.

So I guess my problem is semi solved. I now know the wiring in my car is fine, but I will still need to buy a genuine alternator once another one of these shitty rebuilt ones fails on me...

Let this thread be a lesson to all, buy it nice or buy it twice... :BangHead:

I thought I would chime in as I know someone that has the same issue with a 96 Cobra. He is on his fifth alternator, #5 being a NAPA unit! His car is at a shop that specializes in electrical issues for 30+ years and they are somewhat stumped. Turns out, the regulator is overheating due to under hood temperatures. When the car is cool (just started) alt works fine (14v). After driving just a few miles, the housing of the alt is SO hot, that you can?t touch it for more than a second! As such, the internal regulator is going into thermal failure. (less than 13v, or about battery voltage). Since I used to rebuild starters and alternators, as well as being ASE certified, I am going to attempt to ?remote mount? the regulator to a CPU heat sink and hardwire it back into the alt. I?m on my way now to the shop that has the car. I will post the outcome weather + or-

Best wishes, :wave:
-Pace

PS: I doubt the tach issue you have is alt related.

 

[ttocs]

I would not pin the tach on a alt either but..... I live in a small town but was still able to find a reputable place nearby that rebuilt alts and did a great job. I would always recomend one of these shops as they have had their hands on them unlike the parts stores. They tend to stand behind them more.

 

[l_____l]

I totally agree! I'm in New Orleans and the car is at probably the best alternator shop here. I just came back from there with the owner of the Cobra and explained to them my idea of "remote mounting" of the regulator. At 1st, they were with "raised eyebrows", then realized I knew what I was talking about. I brought them a massive CPU heat sink from a gutted desktop. The 2 hold down screws on the regulator that make contact to the brush holder, would have to be rigged with screws that have the plastic insulator on them, lock washers and nuts on the electrical contact area... effectively, making them "studs". From there, 2 eyelet crimp connectors (with 2 more lock washers & nuts) and enough length of wire to run back into the alternator and connect to the brush holder. That would be the only "hard wiring" to do. The pig tail that plugs into the regulator would just be a matter of lengthening the wires from the OEM harness to the now remotely mounted voltage regulator.

They showed be a version of this alternator (from AZone) that had a regulator with built in brush holder! (a one piece setup)... My "mod" will NOT work with that design! :nono: UNLESS, the brush holder for the other design can be put in place with OUT a regulator! This "one piece regulator and brush holder" is quite interesting in itself, as the regulator has it's own mini doll baby aluminum heat sink, where as the 2 piece design sinks heat to the housing.

At the end of the day, the 5th alternator (a NAPA unit) was fried within 1/8th of one mile. :angry4: Come Monday afternoon, I'll know how my "mod" turned out. I may be able to post photos except for the hard wiring to the brush holder inside of the alternator.

 

[ttocs]

there should not be any reason that you need to go through this unless you have running some massive stereo though. Just curious, are you running under drive pullies? Nothing will kill an alt faster then those IMO.

 

[l_____l]

No "under-drive pulleys". "Bone Stock". ...update...the "shop" is installing a unit (alternator) that costs $50 MORE! They
say it's a unit that can withstand more temps! What a waste of brain cells! This guy (the customer) has wasted upward of $300 USD over a friggin alternator! The previous poster made mention of CHINESE voltage regs... are we to beat each other over the head because of (Chinese) defects? pHucK NO!

So, my divine construct of "remote mounting" the internal voltage regulator in a POS Ford motor product, will have to be discovered by an ALIEN with green hands and feet, whilst they LAUGH!

Think of it this way: Who is "Smarter"? Albert Einstein, ...or Adolph Hitler.
Hitler needed help in tying his shoes. ...Einstein had his tied before he woke.

 

[l_____l]

. .

 

[ttocs]

sorry didn't realize I was now with 2 different people, a seperate post would make it easier to seperate the differencec between you twol

they make alts that have remote mounting capability already but they are a high end car-audio alt that would probably be more then the 300 you are already paying.

My only question is why is it all getting so hot and would really suspect something possibly small and stupid like a bad connection or ground somewhere that has developed corrosion, and added resistance to the circuit that would cause it to run hotter? I have a HO alt(200amps) as well as some amps that could draw all of that 200 amps but never had an issue with over heating. I go it hot enough that over time the rubber boot probecting the wire on the alt started to dry out but the alt has still never failed. Of course that is a different engine so who know but again I would go back and make sure all the basics are good. Make sure you can't wiggle the battery terminals or the factory grounds both from the battery to the chassis and from the chassis to the block and would even consider upgrading the factory power wires to ensure they are not resticing. This is a common practice called "the big 3 upgrade" that a quick search would show what you need to do. Wire and fuse holders could be $40-50 but if it saves you from killing an alt it would be worth it. I have heard about an alt bad out of the box, maybe even 2 but when you are on #5 I would start to look a little closer.