if you need help to quick ID The alternator, the 2g has an external fan (like a GM CS130 or 10SI) and the 3g uses an internal fan (like the Gm CS130D or AD230)

 

AH, lol, I do not have a 2g.
Thank you!

 

That has been my experience with the 2G on two different trucks.

Yes…which is why a new pigtail was always included with a new or reman alternator.

I hardly ever replaced the pigtail. If the connection felt tight and the wires looked ok I did not replace it.

No. It should be a 3G in a 1994. At least the ‘94 351W I bought out of an E-150 was a 3G and not a 2G. That is the only reason I converted to that alternator.

 

I dont know if the alternators also included a sheet explaining why to replace it or not, and if thats still true to today. ive never owned a 2g or tried to replace one, so i cant say i know what im talking about (in terms of buying a reman and getting a pigtail)

Still doesnt mean its the right option, if a owner is comfortable or able to replace the pigtail, a wiring change to make it a 3g vehicle is admittedly more involved but its not much more.

I dont know if the 1g was a internally or externally regulated unit but If it was externally, then I only have experience with a 1g.
The externally regulated alts in the late 70s were cool, you could adjust the set point of the cars charging system with a screwdriver iirc, at the very least theres an adjustment procedure in the service manual.

If i had any say in the matter Id get some gm alternators made up to fit the mounting configuration of these engines. the 7.5 and 4.9 would have the easiest time fitting since its in the same plane as the shaft , but the crossbolting on the 5.0 and 5.8 would require special castings for sure for the front halves

The 4.9 I have is so close to workable except that the top and bottom ear arent level with eachother, and the one ear is threaded and the other is intended to encase the bolt all the way through to the other end of the bracket, making it require machining on a gm alternator with matching ear placements to make work and probably use a nut and bolt on the top ear.
I did, however, personally confirm that at least the pulley would be in the right spot assuming the ears on the gm alternator were in the right spot, iirc they matched the threaded hole ear, so someone could machine this if they were dedicated. Sadly the benefits are not good enough to warrant the effort and who wants to swap their case half everytime they need an alternator, which requires unsoldering the rectifier among other things to make it require downtime.

But the electronics are so much nicer and refined, much more simple, and the regulator uses a shelf-available pigtail and the whole thing would function with only one wire on the regulator simply to the charge indicator
Each one has built in soft-start ability like the taurus (and other small car engine) 3gs only

3g 140 amps to their benefit take up much less space because of how their case is shaped, i presume the stator diameters are similar enough to compare that

 

Yes. It came with instructions and explained why it needed to be replaced. I have no idea if they still do because I have not replaced a 2G alternator in a long time.

The ‘94 engine has a different serpentine belt setup than the ‘89. It also has a 3G alternator with three mounting bolts instead of the two bolt 2G. I bought a 3G wiring harness from a junkyard. Other than changing the green trigger wire connector because one was round while the other was square, it was plug and play.

 

nice
And the true killer of some engines was peoples unwillingness or inability to have read that piece of paper lol

 

Huge "Thank you!" to all respondents. Your insights are invaluable.

I checked my rig earlier and... it's a 2G 80amp alternator. I've been looking at the alternatives and will likely replace in the near future.

That said... are there preferred alts out there that folks swear by? I've been looking at the PurePower's 250 Amp Custom High Output. Anyone have an opinion on their alts or the company? Other alt suggestions?

https://www.tucsonalternator.com/pro...ernator/3-ORG/

 

Add another power wire if you go with a big amp alternator like the 250 you are thinking about
Personally, I would not go over about 160 amps, and I would add a second power wire even with the 160

 

The 2G can have problems at the connector which is why the TSB came out. Many of us have never had any issues with that alternator.

Why do you need a 250amp alternator? I am using a factory replacement 130A. Look up 2G to 3G conversion on garysgaragemahal.com for info on how to do the conversion. It shows what needs to be done to modify the bracket as well as which vehicles have the correct two bolt alternators and how to wire it up.

 

I don't know that I in fact need a 250amp alt. Fair question.

The original questions starting the thread were intended to better understand what's transpired with factory alts from that time period, to understand if they're dangerous and should be considered for replacement, and to understand what others have done to both mitigate the risk of a potentially dangerous situation while understanding what the benefits are of going with a larger amperage, 'modern' alt. If you're saying that one shouldn't upgrade to a 250amp, is there a reason why that is? Sorry, just trying to understand. For the layperson, the idea of more - and more consistent - power appears to be the correct route (especially given the limited investment increase)? Look forward to your insights/comments.

 

A bigger alternator will only provide more power if more load is placed on it, meaning zero day to day difference. Personally, I would save the money and get a standard alternator, unless you need the extra power.

As I posted before, even a reman 2G unit can function flawlessly. An upgrade to 3G would be nice when this one gives out. (I was not given a new connector with the alternator)

 

130A 3Gs always have seemed to bench test higher for me. 150-160A area, as noted by others they put out more *** at lower RPM as well as being a superior design.

If you had a large stereo, heated seats, and auxiliary halogen lamps, maybe I could see a larger unit wanted. I run a basicass 130A on my '88. Just has a small JL 300/2 amp (150x2rms) running the audio, plus the usual bits they had stock. Lights. Hvac. Etc. It keeps up fine.

I pointed out what needs to be done to swap it in previous posts. You were given links by others. It is all over old Stang mag articles too.

 

My '90 is loaded for that year, to include air. However, it's also completely stock - with the exception of the Alaskan Camper sitting in it's bed. Only the camper's running lights are plugged into the truck so it sounds as though the 3G 130amp would be more than sufficient for that setup. Appreciate the insights.

 

the only reason i say dont get the 250 amp is there is first, cost.

tertiarily, (is that even a word?)
theres a few ways to make that more power that might not be ideal:
Its going to involve stuffing more guts into the alternator that converts the AC To DC, which is where the heat that kills components that are trapped inside the case is largely affecting. The stator windings as long as they havent failed , are pretty durable and dont exactly have much to worry about

The electronics hate heat, and output lowers with heat, and heat lowers their lifespan. Another way they get higher ratings is to drop the alternators pulley size so they spin faster and thus are producing more at low RPM, there is a limit of how fast the shaft can spin, and idk what it is but it is important that your crank-to-alt pulley ratio doesnt enable it to get to that speed
Id imagine output will taper off after a certain speed but im not sure what that is. No idea how much is to be gained by this alone, but its devils in the detail. A better charge wire as mentioned would be needed. ID use a dedicated ground on a 3g alternator regardless if you get 250 or 130amp
because theres a threaded hole in the back un-used on them and these trucks have terrible engine grounds. and old.

The 130amp i think will do you well, and not having a special alternator is not only cheaper it means you wont need to do the alt twice if you need to replace or warranty. youd likely be in the auto store or rockauto to get a temporary unit when/if the 250 dies.
A rear camper being used , if you have a need for 12volt source power, id recommend getting a battery that is maintained by your alternator but its decoupled from the trucks loads If your trailer connector is 7 way and you have the relays underhood, you have a wire dedicated to this already
But it can be added fairly easy with junkyard or ebay parts or using a relay and doing your own run