Rear Diff Locked On Its Own, Unable To Unlock

[Raacerx]

Update: Have been too busy to bring it to the dealer yet, appointment scheduled, still removing various overlanding stuff so the truck appears "stockish". I have some other issues to handle as well, transmission related. I think I'll flash the ECU back to stock too (just a Ford Perf).

I was able to get the diff unlocked after putting the rear in the air and tapping the pumpkin a bit with a hammer. I removed the diff plug, but no water came out. The oil smells a bit burnt, but I'm not familiar with this specific diff oil.

I need to locate the breather and see if its plugged.

I did a short drive with my wife following in the other car, no abnormal diff temps or smells. I even played it dangerously and locked the diff and unlocked it, and this time it locked and unlocked.

My prediction is that they're going to open up the diff cover and see some R&P shavings, as seems to be somewhat common here.

Also, 3 feet of water isn't that deep if you're moving. It's only bad when you stop. I'm probably exaggerating a bit, didn't get any water in the doorsills or anything. Most likely 2.5 feet.

PS. I don't have a snorkel but I have a custom airbox that allows me to cover the lower section so it only pulls from the hood.

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[Frenchy]

Update: Have been too busy to bring it to the dealer yet, appointment scheduled, still removing various overlanding stuff so the truck appears "stockish". I have some other issues to handle as well, transmission related. I think I'll flash the ECU back to stock too (just a Ford Perf).

I was able to get the diff unlocked after putting the rear in the air and tapping the pumpkin a bit with a hammer. I removed the diff plug, but no water came out. The oil smells a bit burnt, but I'm not familiar with this specific diff oil.

I need to locate the breather and see if its plugged.

I did a short drive with my wife following in the other car, no abnormal diff temps or smells. I even played it dangerously and locked the diff and unlocked it, and this time it locked and unlocked.

My prediction is that they're going to open up the diff cover and see some R&P shavings, as seems to be somewhat common here.

Also, 3 feet of water isn't that deep if you're moving. It's only bad when you stop. I'm probably exaggerating a bit, didn't get any water in the doorsills or anything. Most likely 2.5 feet.

PS. I don't have a snorkel but I have a custom airbox that allows me to cover the lower section so it only pulls from the hood.

Chances are the Diff oil is just a regular 80w90. If it was a LSD or special type of axle then Ford might of asked for an additive or synthetic oil.

 

[Raacerx]

Update: Truck back from dealer again. After two visits they've been unable to find any reason why the diff wouldn't unlock (or the climate control issues I've been having).

They did another diff oil drain and refill and said nothing was found. I've done some wheeling and road trips since the first dealer visit, and admittedly no issues have occurred, although I've been babying it.

Gearing up for my annual 3 week September overland trip and I'm a bit wary and worried about the overall reliability of the vehicle.

Ford offering me $38k for the truck. I owe a decent amount less than that. Although I have no idea what else I would get.

Can't say the whole Ford dealer experience has left me wanting to buy another Ford, but so far I'm only out $70 for diff fluid, and the annoyance of borrowing my wife's car.

 

[Frenchy]

It's your call here. I say take the chance with the truck on the 3 week trip. Assuming it starts on labor day weekend I say take a quick shake down trip the weekend before. If nothing happens then you should be good.

If after the trip you feel more comfortable trading the truck in, then do just that.

 

[Raacerx]

It's your call here. I say take the chance with the truck on the 3 week trip. Assuming it starts on labor day weekend I say take a quick shake down trip the weekend before. If nothing happens then you should be good.

If after the trip you feel more comfortable trading the truck in, then do just that.

I've done lots of 4 hour or less road trips since then, and some minor wheeling, no 4LO, and it's been ok, but it's tough to have a lot of confidence right now. I've done this road trip 3x with the Ranger already, and each time something has gone wrong. Of course, it's always "worked itself out".

Last weekend it was 114*F in Redding, CA, and we set the cruise control at 73mph and it was totally fine. But that was also 100% flat.

 

[ccasanova22]

I’ve had this before and the only thing the dealer could come up is with the fluid was low. Significantly low, as putting one quart on flat ground still didn’t result in anything coming out with the plug open. They rebuilt the diff (seals) and my problem has yet to return. Not sure if related or not…

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