Well it happened. After 878,000 mi the rear end started to go out. Well let me rephrase that. It had reached a point where it needed to be replaced or repaired because of too much play. I've been hearing a whining noise for a long time but didn't pay that much attention to it as the truck ran fine. It was not very loud. However the day before it made a loud squealing sound when I accelerated hard to 80 mph. I thought it was going to blow up. I took the truck to a shop to have it evaluated and they said that the drive shaft was okay just some play in the rear end. My personal inspection of the carrier bearing of the drive shaft showed very little play but I knew that it could still possibly be bad. So I took it to a shop that specializes in driveline, and they told me the carrier bearing in the drive shaft was bad and that my rear end was loose, as in a lot of play. They suggested that I rebuild both the rear end and the drive shaft. After some thought I agreed and let them rebuild the differential and the drive shaft. The truck has almost 900,000 miles on it so I figure what the hell. Do it now or do it sooner than later. So they put all new parts in the differential including pinion gears. I did not change the gear ratio I left it 3.73. I am very happy with that gear ratio especially with the price of fuel nowadays. Anyways I have a Bank's pedal monster that allows the truck to accelerate very quickly. No pedal lag. So after about 3 days I got the truck back and I am breaking it in slowly. Nothing very heavy and no long distance. The differential has all new parts so you have to be careful with it or you can damage it. In fact I'm going to change the gear oil in a few weeks just to have fresh oil. I bought some amsoil 75 w140 and have it at the ready along with some Permatex sealer made specifically for differentials. Because it has new parts the metal contaminants like small metal particles can contaminate the gear oil and cause bearing damage if you don't change the oil soon.Years ago I had bought a brand new 2008 f550 and ran it hard as soon as I drove it off the lot including heavy loads and long distance. Well guess what? 2 months later I had to take it back to Ford complaining of a loud whining rear end. They replaced the entire differential. They did not tell me to take it easy. I drove it like I stole it. So I have learned my lesson. Take it easy. So far so good I have about 400 miles on the rebuild. I think it is now ready to take it out of town. I will post some pics when I change the differential oil in a few weeks. Merry Christmas and Happy New Year to everybody!

 

Rear End certainly don't owe you anything at that mileage. I wonder what your rear diff OCI was. Do you have a limited slip? I had to add the modifier to mine when I got it, was chattering on turns.

My F150 has the same drivetrain as yours, 6.2 and 3.73s, good gas mileage for what it is. Turns 1500 at 60, 20" wheel. I guess it is not even broken in at 190K :lol: Your thread made me look for that powertrain.

I'm curious if you had any coil issues with your 6.2

Anyway Merry Christmas/ Happy New Year and hoping to see another 500K on that 6.2!

 

My rear differential oci was add oil when it started leaking from the pinion seal. No 🤣 I'm not kidding. I never removed the differential cover and cleaned it out or replaced the oil unless it was leaking. Fact. I bet it had a lot of life in it but I just did not want to take a chance on it grenading out in the middle of nowhere with a load on my truck. I'm a hot shot driver. no limited slip. Every once in awhile a coil will go bad but they are easy to replace. When it rains real hard sometimes the water penetrates the engine bay underneath the wipers so I had to place plastic over the back of the motor to protect it from water intrusion. Otherwise water falls into the back coil by the firewall and causes a misfire. So be aware of water intrusion as the truck ages. The Amsoil gear oil that I bought has modifiers in it. The differential shop told me not to use full synthetic but to use regular conventional oil. They say modifiers can cause leaking of the pinion seal. Maybe it does I don't know. My pinion seal did seem to leak a lot with synthetic oil. So I'm taking a chance with this amsoil but it is supposed to be the best from what I understand. We will just have to wait and see what happens.

 

As a side note if you buy your coils from O'Reilly Auto parts I believe they give you a lifetime warranty. Ford just gives you a 2-year warranty

 

I bought a pack of coils for $100 (all 8) on Amazon and they are holding up very well! One went bad after install and 3 days later a new one arrived when I emailed. I have my old coils just in case I need to replace one (only the boots were bad). That set of coils was close to what the boots cost!

Amsoil is very good stuff, doubt it will cause any issues.
Never heard of synth causing seal leaks, who knows. None of the diffs I have leak, use valvoline.
I know synth contains some friction modifier that does not work well with Fords.
All 3 cars below (explorer, f150, MGM) needed the ford stuff to stop the chatter. Explorer has Carbon Fiber cobra clutches and was undrivable until I added it.
I am starting to think it is Best to buy gear oil with no modifier then add the ford stuff if you have an LS, but Amsoil is the best.

The factory fill really went a long way! And you really use your truck to the limit!

 

 

awesome report

 

Ed, looks like you haul alot of oilfield equipment.

 

I wonder if he needs a CDL for that.

 

Yes you need a CDL for what I do.