Alternators….

[TXStreetSN95]

So I have a mildly built 302…f303 cam… I’m on my second alternator… I’m wondering from the gurus on this forum, is my cam killing my alternator… is it not getting the proper idle rotation for the alternator to work properly? Reason I ask, I drove my car for less than 20 minutes today, keep in mind it was idling for awhile as I did some work to it, and I was letting the engine warm up before I took it down the road. Pulling back into my shop, after a run time of about 40 minutes max, the battery was dead. Brand new battery, never had any issues out of it till today. It is a stock oem alternator from “oreallys”…. My nickname for them because everytime I order parts to my shop, I’m left saying “oh really, the wrong part” lmao. Anyway…. Someone help me out. Should I be running something different?

 

[Daryl]

Not for nothing, but I am a firm believer in starting from the beginning. Did you check the wiring? Check its condition, connections, ground, etc.

If that all checks good, maybe it’s time (after 2 poor alt’s) for a better quality brand alternator? And stop throwing good money after bad??

Good luck and keep us posted. Cheers!

 

[ttocs]

are ya runnin underdrive pullies by chance?

 

[lwarrior1016]

I will tell you, advance, oreilly, auto zone, all of the alternators are trash now. I had to put 6, yes 6, alternators on a truck one time to get one that would work. It would go on and charge fine for 15-20 minutes, then stop charging.

My advice is to find a good aftermarket solution. You’ll pay more, but it’ll work.

 

[Mustang5L5]

I ran a Bosch alternator on my Fox. Installed it back around the year 2000. Had underdrives and it was reliable as hell.

When i rebuilt my engine about 2-3 years ago, I tried to disassemble the alternator to clean up/paint the case and broke it by accident. Bought myself another Bosch alternator off Rockauto. It's been a couple years, with an aftermarket cam, and no issues.

 

[duh09]

Which alternator are you picking up? There is a big difference from the bottom line 1 year warranty to the top full new LT alternator. I’ve got a full new lifetime Ultima Select sitting in the box to go on mine but it’s not a regularly driven car and it’s not a big deal to snag it off and swap it at work.

Sometimes it does take a few to get a good one in the cheaper lines, but you can get them tested in store before leaving to make sure.

I don’t remember the number right off, but I think we have something like a 4% warranty rate on our alternators top to bottom, but there are some numbers that are a little more prevalent with being not up to par and for some reason they tend to be Fords- I will not sell our brand of 6.0 Powerstroke alternators after warrantying a half million of them.

But anyways, O’Reilly spill over.

 

[Michael Plummer]

Before buying another alternator, you need to make sure you don't have a wiring issue or a pulley issue.
The 2G was common to all Mustangs from 1986 to 1993. It was replaced by the 3G in 1994. (Feel free to check me on that because I'm going off on memory.)

Alternator calculator based on pulleys

RPM Calculator

www.paperformance.com

Troubleshooting your alternator

https://www.paperformance.com/content/3G4GDiagnosis.pdf

FYI
Never under any circumstances remove the battery cable while the car is running! Doing this can damage the internal voltage regulator, making the alternator no longer charge.

Good luck
Michael Plummer