Cobra Alternator issues. Do i buy a new one, or is it something else going on?

CobraGOTVENM

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So I have a Cobra with engine redone by Pauls Automotive Engineering in Cincy. it has 2.76 pulley and stock lower. A little while after i got it back when the revs got above 3500-4000 or so the battery light flashes. I know these are riddled with alternator issues due to high RPMs and heat and the current alternator is the stock one. However, when the car is turned off then restarted it shows 13.5-14V and stays there at idle for a while but slowly creeps down as it heats up. Can even drive it a few miles before the battery light comes on at lower RPMs. Just asking if it could be anything else with how it charges for a while. And if I do replace it what do I need to go with. Seen mixed reviews on PA Performance. Preferably something with a warranty with how these go. Thanks
 

Dave.O

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It's probably either belt slip or the alternator going bad. I'm on my third in 40k miles, but I road course my car. I recommend pa performance with a 3.2" pulley. 3+ yrs on mine


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MG0h3

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Sounds like heat related failure to me.

I'd look at a unit with a remote regulator like nations. Couple other brands that are recommended.

Some just get a lifetime napa or autozone and get a free one every time it bites the dust.
 

Huachipato

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I'm in the camp of getting one from brick and mortar location. When they eventually die - just go swap it for a new one. I am on my 3rd alternator and engine is basically stock on my car.
 

MG0h3

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Honestly you should check connections too. There’s a reason there are cable upgrades for our cars. Heat does cause resistance so that could be part of the problem. Weak connection, car gets hot, you load it down and the bolts drop.


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CobraGOTVENM

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Thinking I'm going with PA Performance with the 3.2" pulley. They offer lifetime warranties on them now. And it doesn't get driven hard. I have 2.76 s/c pulley with stock lower what size belt? Think I've read 1 inch difference.
 

me32

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Have you looked into nations or mechman alts? They both make high quality alts.
 

Comp04svt

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Thinking I'm going with PA Performance with the 3.2" pulley. They offer lifetime warranties on them now. And it doesn't get driven hard. I have 2.76 s/c pulley with stock lower what size belt? Think I've read 1 inch difference.

I would honestly look into the 200 amp alternator J2fabrication sells, along with the wire upgrade that will be necessary. Top notch product. I've been super happy with mine. The price is reasonable and they fit just like stock.

I wouldn't put a 3.2 pulley on it if you have a stock lower as it may tend to spin it too slow. J2 offers a slightly bigger pulley than stock, which is 2.71". I would consider doing that instead.
 

CRidge

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I have a new J2Fabrication 200amp alternator I would sell for $250, cost $315 new
 

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Dave.O

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Stock crank pulley and alt pulley combo is over spun from factory. That is the reason Alts are failing regularly in my opinion. Slightly underdriven alt pulley will help with this


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jrgoffin

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Stock crank pulley and alt pulley combo is over spun from factory. That is the reason Alts are failing regularly in my opinion. Slightly underdriven alt pulley will help with this
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Total forum rumor. These weak 105A alternators when under-driven just perform more poorly and then will eventually kill off the battery. The only reason to change its pulley is if the crank pulley size is different.

They are just V-6 alternators anyway, so the easiest way to get back on the road is to buy one of them, swap the pulley and post, then you are all set. Lots to read on them:

http://www.terminator-cobra.com/electrical.htm#Alternator

Or this:

http://www.modularfords.com/threads/235857-Terminator-quot-Alternator-101-quot
 

speedoflife

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Total forum rumor. These weak 105A alternators when under-driven just perform more poorly and then will eventually kill off the battery. The only reason to change its pulley is if the crank pulley size is different.

They are just V-6 alternators anyway, so the easiest way to get back on the road is to buy one of them, swap the pulley and post, then you are all set. Lots to read on them:

http://www.terminator-cobra.com/electrical.htm#Alternator

Or this:

http://www.modularfords.com/threads/235857-Terminator-quot-Alternator-101-quot
Personally, I have not seen a documented case of a 3.2 alt pulley/stock lower combo killing a battery. In fact, there are a few cases on this forum where people have run this combo and not had problems. If the alternator can be slowed down, it will help reduce heat and prolong its longevity. Maybe you have heard of cases where people have run into issues with a 3.2 alt/stock lower combo, but I have not.

Your Terminator knowledge/research far exceeds mine, but I have read your entire site and scoured the forums regarding this topic. Maybe I'm wrong but it seems that for "normal" usage (not idling for excessive periods of time), a 3.2" alternator pulley provides an advantage, even for those with a stock lower.

For example:
I run a 3.2 with a stock lower. I also do 20 minute sessions on track from time to time. I wanted to slow the alt down a little, hoping it would help it live a little longer.

It's been on for WELL over a year with no ill effects. Charges fine at idle, A/C(on full) and cooling fans(on high) with headlights on, don't seem to bother it a bit.

The battery is approaching "that age" so I'm expecting to have to replace it soon, but no symptoms so far.
 

Drive XR7

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First, Paul's Automotive in Cincy is a great shop. My buddy's brother runs it. They installed the FLSFCs and new front bushings on mine before I bought it.

Heat kills these alternators. I'd replace it now so the car doesn't leave you stranded somewhere. On my last Cobra, the alternator burned up at 30k miles when I was DDing it. Ford replace it with a Motorcraft unit under warranty.

I've heard if you do replace it, get a new metco pulley so it's not overspun. Other than that, this is still a chronic issue with our cars and I don't know of any solid tried and true fix.
 

perry2k12

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Seems to me like people really over complicate issues like this. I bought my car with 45k miles... the alternator took a dump at 50k (I don't know the history of the alternator on the car). I went to my local napa and bought a lifetime warranty alternator and have put almost 10k miles on it with no issues...
 

351stang

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I'm in the camp of getting one from brick and mortar location. When they eventually die - just go swap it for a new one. I am on my 3rd alternator and engine is basically stock on my car.

I bought an Autozone gold years back with a lifetime warranty. I just swap them out. I'm on my 4-5 one in 14 years.
 

Dave.O

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Jr you have helped me out several times with our experience and input. But I will have to politely disagree with you on this one. I am currently on my longest lasting alternator with that combo. But I do high rev my car on open track regularly which makes my application harsher than average. You are correct though regarding undercharging, I previously had a 3.5 " pulley that would kill battery on long idling. Switching to 3.2 corrected this, but occasionally in traffic I will stab the pedal to increase charge


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