I recently had my G2 (third) alternator do a meltdown on my 89 F150 with the 4.9 engine. Both plastic plugs, and the wire near the relay on the fender burned in two. It has a fusible link on it, and I thought that was the purpose of that. I haven't checked the big fuse under the relay, but I suspect it didn't blow. By the time I got it home, based on the burning smell, it was about ready to catch fire, like some of older F150's have done. The smoke smell lasted for hours.

I am going to the G3 now, and I understand that on this 4.9 I can use a 130 amp alternator with bolts at 6:00 and 12:00, with 8.25in. spacing, which can be found on mid '90's Taurus 3.8. Some filing of the bracket would be necessary. RJMinject.com has a 3G, 95amp alternator, which has the same bolt pattern as I have now, which is 6:00 & 2:00 and 7in. apart. This would bolt right on with no filing on the bracket, and all I would have to do is change the alt. wiring to the relay. I have a/c, power windows and locks, standard radio, and I don't plan on any new add-ons. The RJM alt. puts out 80amps at idle, and 120 at it's very max output. Would this be an adequate amount to handle times when I have the a/c and headlights going, for example? Thanks for any help.

 

I have the stock 95 amp unit on my 95 F150 and I have no issues but I'm all stock with only an aftermarket radio. I do have an Rv with electric trailer brakes and a 600w 120 volt inverter, but no high draw components like a winch or off road lighting systems. I did replace it at 200k miles with another 95 amp unit. Check the wiring from the alternator to the battery and also all of the grounds.

YMMV
rikard

 

I did the 3g swap not long ago. The alt carries the load just fine which for me a
is lights and AC. Your stock mount is 6 and 2 and the new will be 6 and 12. Mine went right in with very little filing to the bracket and I went with the 160a. Here is the thread with pictures.

https://www.f150forum.com/f10/3g-altenator-165829/

 

Thanks for the info. Where did you do the grinding on the bracket? Was that on the back side of the top bolt hole? Also, what did you have to lose to grind it down? Thanks Bill

 

oops. Let me reword the last post. Thanks for the info. Did you grind the bracket behind the top bolt hole? What did you use to grind it down?

 

Yea.. behind the top mount hole. The bracket is thickened there and I was concerned about serp alignment. Probably didn't need to be done but Im **** about sheet like that, it may have worked just fine without grinding.. I used a high speed with a rotary file. Another way to get it done would have been to file the mounting ear on the alt.

 

Hey 5 Rangers, you really posted great pictures explaining the changeover. I ordered my alternator and the cable kits form RJM, and I got them in a week, well packed, and in perfect condition. I'm working on the charging cable, and I have a question. On the alternator, I have the connection for the charging cable, and it has a red plastic piece that has a cutout in it where the cable should lay. The problem is that if I set the cable in that cutout, it will be in the 7:00 position, rather than the 2:00 or 3:00 position,like your picture. If I place it that way, I'll have to bend the cable to keep it away from the header on the engine. Do you know if I can turn that plastic piece so it comes off the alternator like yours does? I hope this makes sense. If you don't know, I'll try calling RJM. It isn't too easy to reach them by phone or e-mail, so I thought I would try you first. Thanks for any help.

 

I understand, I think you can reclock that insulator but I am not sure exactly how, I think either on RJMs website or with the kit there are instructions on pulling the back off the alt. But probably a call to RJM..

 

Hey, thanks for getting back to me. With repeated calls, I was able to reach RJM and he told me to just clip away a little of the plastic on the smaller slot. He said just make sure not to take off too much, where the cable would be able to turn and ground out. I'm sure that wouldn't be pretty. I installed the fuse holder yesterday and I kept your installation tips in the back of my mind. I can see where you could easily install it and not realize the hood spring comes down there. Thanks for that. My jack is mounted in the other space, so I had to go over a little further on the horizontal plastic over the wheel well (where one of those cans is horizontally mounted. It was really cool the way they show you to solder the charge cable ends and to heat the shrink wraps. The whole kit is worth the money.

 

Cool... yes I thought the solder slugs and the lugs were pretty cool. Just have make sure you heat them enough that the wire goes in and solder squirts out otherwise you'll have a cold solder joint. Make sure that you disconnect battery ground whenever working on electrical generation as the fuse will open in a flash.