Good ol Midnight, 89 F250, 4.9 and 360,000 miles, the only ongoing trouble has been the alternator. Lights and heater/ac seem to use up almost all the available power from the OEM 65 Amp alternator at idle. I've lost voltage regulators, had two non connector related alternator fires, most seem contained to the running alternator and were solved by unplugging it. The trailers I tow have a bit of load as well, lots of running lights and electric brakes. I've tried the rewound hi output alternators that usually die by spilling solder all over the air pump. Six alternators in sixteen years.

Anyway, this weekend I called it quits I zipped down to pep boys, not quite sure of what I'm doing, just like everyone else. The 4.9 bracket has two sets of mounting holes in place, 8 inches o/c for the 180 degree mounting points with 5.5 inches of clearance to the intake manifold. I asked for an alternator for a late model Taurus 130 amp, perfect, there are two options on the 3G 180 degree mounts and what looks like a 135 degree mount.

I picked up a new bolt for the top bracket of the alternator, metric instead of standard thread. First impression was the alternator was clocked wrong, easy enough to fix, remove the 3 housing bolts, remove the pulley nut and pulley, gently tap the case with a plastic hammer to seperate the front case half from the windings, rotate the front case 120 degrees to put all the power terminals facing away from the engine. I used the oem alternator pulley and a 0.030 spacer from behind the nut to get clearance between the pulley and the case, discarding the supplied larger (2.5 vs 1.75 inch) pulley

Plenty of room all around, alternator sitting about 1/8 inch away from centerline so a bit more tug to fit the oem belt back in place. Factory regulator plug remains unchanged, white wire from OEM power connector gets spliced to a field tap plug ($4 from local alternator shop) 2 #10 wires clipped back to splice where yellow wire goes to regulator. New #4 alternator wire runs from alternator stud to starter solenoid stud. New split loom anti chafe to replace all the original brittle stuff and give it a good run. 100 amps at idle, max fully warmed up test of 145 amps. All lights and heater running, everything warmed up I see about a half volt drop from 14.6 volts down to 14.1. Maybe now I can stop carrying a spare alternator in the toolbox.

-Jason

 

I'm impressed. You did something I'd never thought of.

Good luck on it. I thought the stnd amp for our 4.9 alts were 85 though.

 

I think there were a few alternators for that specific mount, perhaps 65 and 75 amp, but still there was only about 45 - 55 amps at idle, even from the special high output ones. I do see one change so far, hood open after a good warmup, lights/heater running, the standard alternator would have a case temp of about 350-400 degrees. Under the same seat of the pants test with the 3G alternator, I'm seeing a case temp of about 125 degrees. Perhaps the internal fan working with the larger case is moving more air and keeping everything happy.

I would imagine your local alternator shop would for no charge pull a 3G off the rack with the 180 degree mounts, swap the pulley, reclock it and give it to you for the price that was on the box anyway. While this part took me ten minutes, I've seen the alt shop do most of it on the counter in less than a minute.

I posted it to this model truck section cause we're the ones with the flaky alternators and maybe someone who was thinking of getting a newer truck because of the fear of alternator fires and failures will give themselves an upgrade and save getting car payments

-Jason
fast_st@hotmail.com

 

Autozone will change the pullys and re-clock the alternator, however youll need to find someone that cares, and it will void the warranty on the alternator.

 

Well, that would depend I suppose if you ever need to return it that the counter person has a clue that the alternator has been modified. Usually its buy a new one and bring back the old for a refund. Easy enough to restore to original condition prior to dropping it off. Hopefully with the wonderful engineering of the 3G, I won't ever need to change it before the 500k mile mark.

-Jason

 

well there is a sticker that has to be cut to clock it, and without it they will not warranty it, thats all, i wouldent worry to much about it though. i have had them do it for me before, for an s-10 blazer, with a 350 conversion.

 

Ahh, gotcha, though I did give it a quick look the VIP auto parts alternator didn't have any stickers/decals or paint dots on the bolts, pulley nut or case halves. Somehow I'd almost doubt a sticker would survive more than a couple years esp if you like to pressure wash your engine. I had a bit of misfortune with warranty claims back in CA, purchased an alternator from Winchester auto and when I went back on the lifetime warranty a couple years later, they stated they had switched suppliers and they could honor the warranty but I'd have to eat the core charge because of the new vendor. Maybe someone from Cali would have come back with 'dude, that's harsh but okay' sadly enough that isn't what they got. The slip said Winchester, not joe blow alternator shop, one of those get the regional manager calls. I really really like my local alternator rebuilding shop. They don't have lifetime warranty but they will do great work and have reasonable prices. Also if I'm under pressure, usually its service while you wait though the part won't be freshly painted where applicable.

-Jason

 

I have a '92. I am on the 3rd or 4th alternator. The plastic connector keeps melting down. The power indicator on the dash is all over the place and not consistent. Some days it is dead center. Some days it is over charging. You can guess the other days. I put an 85 amp (I think) in there and it does not seem to effect the situation. I will keep this tip around. I expect to have to do this again in about a year.

-Thanks

 

everyone I know with 80's fords has been through more than 1 alternator. My voltage regulator was screwed and it fried 2 batteries before I discovered the problem. that was the regulator on alternator #2. I have been problem free for about a year with the new voltage regulator.

 

Keeping in mind that the volts on the meter indicated are not actual, though there are lines they don't seem to match up. Just clear of the battery legend I'm seeing 14.25 volts at the battery. Pouring on a load shows middle sweep at 13.6 volts. Way over yonder down toward the first white mark isn't 11 volts, its about 12.5 My normal swing seems to be just at the high and low/mid extents of the battery legend.

Another hard lesson I learned is about most "High output" alternators, something with more beef that a factory output in the same housing. I know there is an EE out there somplace, but the HO alternators change the configurations of the windings to shorten them up, making less internal resistance with higher peak current flow, but there is a trade off. The swap is you loose quite a bit of output at idle, I believe its switching the internals from a wye configuration to a delta. What I'd suggest is you want a voltmeter, radio shack style or better, measure your batt voltage key on, engine off, make a note of it, should be above 12v. Compare with the dash meter. Start and run should show about 1.5-2 volts above that. Again make a note of the dash, then crank up your heater and lights at idle, should be about 1 volt less than the max indicated. If you have the cig lighter, borrow the power wire from the back to plug your meter into. Most automotive volt meters aren't very accurate. We do have a nice one in the ambulance, its an 8-18 270 degree sweep, really lets you keep an eye on the running voltage. In general most oem instruments aren't that accurate, just there to give you an idea of a normal range.


-Jason

 

I did a search and found this. http://www.mustangmonthly.com/howto/26599/
Seems like you've got the right idea, but maybe add a wire/fuse link to the output wire for safety.

 

Long run followup to the 3-G conversion;

I'm not running a fuse of any sort, just the 4ga wire from the alt output to the starter
solenoid. The output is still wonderful after about 30k more miles on an over 500k engine. I have found one problem, after startup and if inducing a heavy load, aka jumpstarting something dead, the belt friction is overcome. To fix this I have one idea, certain that part of the issue being this. Any OEM application of the 3G alternator has the belt wrapped 'round the pulley 120 degrees or better and the 4.9 only has around 90 degrees or less. There is an extra mounting hole and a 2" idler pully from napa complete with a bolt is about $15, I'm going to add one extra pulley to the alternator bracket and increase the wrap to about 110-120 degrees. This should eliminate any belt slippage.