How many Miles do Ford Alternators last?

interstategar

Veteran Expediter
How many miles do Ford alternators last? I have a 2012 Ford E350 that's been in service for about 3 1/2 years and have 207K miles on it. I only run th the Qualcomm and a Sirius radio, so I'm not giving it a heavy duty work out running a coffee makers or an inverter etc. Its the standard alternator that comes with a 5.4 L gasoline engine. I thinks its 100 or 125 amp. I could wait until I show a battery light on the dash, but if I can get an idea how long they last, I'd rather just stick a new one in while at my home base then doing it on the road.
 
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Turtle

Administrator
Staff member
Retired Expediter
It's probably easier to tell someone which carrier will be the best one for them than it is to put a time or mile lifespan on an alternator. There are too many variables.The rotor is spun on a needle bearing, which can break due to excessive wear or dirt and grime that can build up inside, the diodes inside the voltage regulator will fail after a time from the heat from the engine putting an extra strain on the part.

It depends on the vehicle, the engine, the conditions in which it's used, how much electrical equipment it's regularly operating and so on. You are giving it more of a workout than you realize, though, even without using an inverter or coffee maker. The on board computer and sensors are using quite a bit. And driving down the road with headlights and air conditioner on may be close to maxing it out.

Some cars may lose an alternator at 40,000 miles while others may continue to operate well after 100,000 miles. Medium duty vehicles, like F- and E-350s have a heavier duty alternator that should last 200,000 to 250,000 miles, generally speaking. That doesn't mean they won't fail at 75,000 or last for 300,000.

They do get weaker over time, though, as the diodes and brushes wear. With a cold engine, start it up and use a voltmeter to measure the charging voltage at the battery terminals. It should be 14.0 volts, give or take a point. (If it's a hot day and the engine is already at operating temperature, the voltage will be less, like 13.8 or less.) Now start adding things like headlights, then radio and high fan speed and air conditioning. If the voltage hangs tough at the batteries the alternator is fine. If it drops significantly, then the alternator is on its way out.

At 200,000 is getting close and it's good to be thinking of a preemptive replacement. I replaced mine at 250,000 miles and carried the old one as an emergency replacement. The new one at 120,000 miles threw the decoupler pulley so I'm glad I had the spare handy. The spare only lasted about 50,000 and I replaced it. 240,000 miles later I replaced it again because it was getting weak, what with time, hours used, oil and grime all over it.

So I think replacing yours soon is a good idea. Either keep the old one as a spare, or have it rebuilt and keep as a spare. I would recommend replacing it with OEM or a very high quality aftermarket (like Denson, who is also an OEM for many auto makers). Stay away from the cheap ones like, say, from from Autozone, as the alternator is a critical part for what we do.
 

brokcanadian

Veteran Expediter
Owner/Operator
My single longest lasting replacement one was the Import Direct brand from O'Reillys auto parts...just about 400,000 miles...no idea why, probably a fluke but they're cheap GOOD junk

All my Ford alternators would fail between 300,000 to 400,000 if we're talking original...buy the spare now and keep it with you if you want to push it (along with a new belt)

Just read it's a gasser...buy that replacement so you have it with you!
 
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Turtle

Administrator
Staff member
Retired Expediter
My single longest lasting replacement one was the Import Direct brand from O'Reillys auto parts...just about 400,000 miles...no idea why, probably a fluke but they're cheap GOOD junk
Might not have been a fluke as much as it was luck. Some aftermarket parts are the exact same part as the OEM part, made on the same manufacturing line. They just stick it in a different box at the end of the line. I've witnessed it at Mahle, Denson, and know someone who works at the ZF plant in northern KY. My $2600 dealer priced ZF steering rack ($1500 at Europarts) was $450 in the aftermarket box. Same exact part. ZF no longer makes racks for 04-06 Sprinters, but Bilstein still does.

The problem is that when you are buying the parts it's almost impossible to know if the part is an actual OEM part or if it is made by someone else. You pretty much have to already know that information and then go looking for the correct aftermarket part.
 
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Mailer

Veteran Expediter
Owner/Operator
My first van was 2006 5.4 L Ford Eco Ext. Bought used at 152000 miles. Since it was a GE fleet van, I'm pretty sure the alternator was replaced with the OEM before I got a hold of it. It went out around 555000 miles. A few weeks before it went out, hard starting and weak or dead battery were the symptoms. I jump started and everything was fine. There was no indication on the dashboard that the alternator was not charging. When it finally gave out, it was at the gas station. Nice!

If you think yours will go beyond 207000 miles and and want to keep it, a fully charged spare battery will help you to get the nearest repair place. That's what happened in my situation, but the spare only lasted about 40 miles. Lol...

Replace it now, you'll feel better. Lol...
 

Turtle

Administrator
Staff member
Retired Expediter
Unless there is a mechanical failure, like a broken spindle or something, alternators just get weaker and weaker over time. The ScanGauge II that I have displays the battery voltage, and the battery monitor I have displays the charging amps, so for new it's pretty easy to see the alternator getting wreak.

Instead of charging at 13.9-14.1 it'll charge at 13.3-13.6, or even less. Anything 12.8 volts and above is still technically charging, which is why you won't get a battery indicator light on the dash, but instead of recharging the starting battery in an hour or two it'll take many hours at the lower voltage, which is why one of the first obvious signs of a bad alternator is a weak or dead battery from being chronically undercharged.

With a new alternator and about the 50 amp hours drawn from the house battery bank, the alternator will steadily push 20-25 amps intro the bank during the bulk charge phase. When the alternator is weak it's more like 8 or 10 amps, or even less.

As the alternator gets weaker it'll still run stuff and charge the battery, if just barely, right up to the point where it won't anymore. With high mileage on the alternator, periodically checking the voltage with a meter will give you a good heads-up when your alternator is failing.
 
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greasytshirt

Moderator
Staff member
Mechanic
I'd be more concerned with the belt idler or tensioner failing first. When the idler bearings fail (and they will), the pulley will cut a slot (or even a hole) through the timing cover.
 

Turtle

Administrator
Staff member
Retired Expediter
Yep if it ain't broke don't fix it!
I can't imagine that would be the motto of the Safety Department at your carrier. LOL

I'd sure stick a voltmeter on the battery terminals while that thing is running and see what the voltage is, though.
 

fastman_1

Veteran Expediter
Owner/Operator
I can't imagine that would be the motto of the Safety Department at your carrier. LOL

I'd sure stick a voltmeter on the battery terminals while that thing is running and see what the voltage is, though.
It gets a complete once over every weekend.
 
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BobWolf

Veteran Expediter
Owner/Operator
About ten years ago I had a short term contract as a machinist at Brunner Int. in Medina NY.
I was working on the line cutting air brake S cams. It didn't matter whos name the box had on it Bendix, Spicer, etc., the part was the same with minor differences like a bore for a set screw or a radius was different.

Another point is whats the difference between Aliant, International, and CAT for fuel injection parts.
two MAJOR things. 1 The box 2 The price.

Its all about the quality. Leeseneville
 
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BobWolf

Veteran Expediter
Owner/Operator
I was going to say Leeseneville / Prestolite is the OEM starter and alternator for class 6 through class 8 trucks. They also make severe duty alternators for light vehicles as well. theyre not cheap, but they are usually servicable as far as swapping out brushes, diodes, etc.
 

BobWolf

Veteran Expediter
Owner/Operator
Leeseneville / Prestolite is the OEM starter and alternator for class 6 through class 8 trucks. They also make severe duty alternators for light vehicles as well. theyre not cheap, but they are usually servicable as far as swapping out brushes, diodes, etc. You can get them with the ability for some serious output.
 
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