I was wondering how long I could reasonably expect a rear diff to last in my truck. It's a 2017 XL 2.7 and has 35500 miles on the clock. I don't tow with it or spend much time off road and generally its used as a car would be - school run, shops, camping etc. Nothing major.

I noticed the tell tale diff whine a week ago, so booked it in as its still (just) under warranty and the dealer replaced the diff no questions asked!
I asked if it was normal for a F150 diff to break at 35k or whether something had caused it, but to be fair they weren't interested in determining why it broke. The service guy just said '...yeah it happens. Its not unusual to have 30k trucks with broken diffs...'

Are Ford making their diffs out of chocolate now or this is the state of modern vehicle parts? How long can I reasonably expect the new diff to last? Thanks

 

I think there was a guy who just hit 200k on his 2.7 with only a torque converter replacement. Look for the thread a ways down

 

I think the diff will last the life of the truck in most cases. It's pretty rare to have to repair or replace one. Most won't ever experience high water but if you drive through high water, high enough to cover the diff, the diff fluid should be changed asap to ensure there was no water intrusion. Off road vehicles fording streams are the most susceptible to this and most know to change fluids often. Transmission, transfer case and front diff on 4wheel drive trucks also need new fluid.

 

I believe the service guy was wrong.

 

Just had my rear rebuilt on my 2016 with 48k, bad pinon bearing, covered under Powertrain warranty

 

I’m literally dealing with this right now. 2018 with 8,000 miles. Started hearing a whiling/humming noise as I accelerated past 40 mph and I’d hear it wind down when I slowed lower than 40 mph. The dealer took a look at it, said the noise was coming from the front diff so they opened it and found metal shavings in the oil. They replaced the front diff yesterday, under warranty.

Makes me kind of worried I only have 8k miles in less than 1 year of ownership and the diff failed already.

 

I agree - having spent 30 odd years around engines/vehicles I thought it had broken early. Granted, i'm not in the industry anymore and things change but to me a diff is almost 'bulletproof'.
The dealer did mention in passing that the last time it was in for a service they noticed a diff oil leak and changed the gasket...! Who knows? Probably overheated. Anyway it was done for free only now i'm concerned that in another 30k I will be paying for it!

 

Yep - thats exactly how I noticed it. Around 40mph and then off the acceleration and it started whining. Mine was the rear but Im sure it sounds the same as yours. I was just blown away at how the dealer was non-plussed about it all and changed it as if it was an old wiper blade..

Doesn't matter to me as it was free, but next time it wont be...

 

The service guy is an idiot. Are there early failures, like mentioned above? Absolutely. But are there F150s with exploding pumpkins on the side of every highway? Absolutely not.

A big part will be how you drive it. Tune the crap out of the engine and burn out at every red light, and you'll crap a diff faster than someone who drives in a sane manner. Also, maintenance is a big part. I don't believe Ford's maintenance interval is sane.

 

The only diff I ever managed to break was the front diff on a Dakota quite a few years ago now... It was a fairly steep hill climb, and I probably managed to shock load the front gears enough between losing traction and gaining it again on one side, that it actually broke some teeth in there. You'll know when that happens right away! I think that truck had 7.5" front gears, so perhaps a bit undersized for even my stock Dakota, which was less than a year old when that happened.

Dealer replaced Ring & Pinion under warranty, and it was OK until I sold it.

That was one reason why I made sure to opt for the 3.73 E-Locker rear axle on my new 2020 F150. No shock loading back there. If Ford offered a front locker, I would've paid for that option also!

Then again, I have mellowed out a bit with age, and wouldn't attempt now what I used to attempt 20 years ago!