Yeah, I drained and filled a couple of times and then drove it up and down a straight road in 4x4 a few times. the final time I made sure to get as much fluid out as possible and filled it up. It seemed a lot better so I left it. I might do it again if I feel like it.

 

that's similar to what mine looked like. if i recall at the time it had the consistency, and looks, of a vanilla milkshake.

 

Apparently that's what it looked like (again) when the diff was pulled and serviced, after i ran less than 50 miles on the new stuff, probably more like 25 miles.

 

At least it doesn’t look like this after 1k miles and one month.

no noises.
works fine.
lariat so I have the 4A/4H if that matters.

Not sure if the last guy didn’t suction out enough of what.

 

This is some weird stuff here. I cannot believe the diff air would exchange so many times to bring it that much humidity.
Could it be air-entrainment?

And the marking compound theory......that's a LOT of pigment.
Do they DIP the ring gear in the marking compound?
Youu can see the ring gear thru my hole, there's no remnants of marking compound on the gear.
I keep hearing that theory. Is it on ALL Ford vehicles? Why not on the REAR diff too then?
There's not much corroboration for the marking compound explanation.

I found the same milkshake in mine at 55k mi. I drilled the cover to drain it then added a MOPAR ribber diff plug.
I posted a HOW-TO thread called

drill front diff cover "on-car" for rubber drain plug (how to with pics)

: https://www.f150forum.com/f2/drill-f...w-pics-496356/



The air pressure also pushes the plug out (captured on the mandrel).

Dorman differential plug costs 3.29 at Autozone.

I intended to build a little skidplate for it because it is forward-facing.
Are they ever forward-facing on MOPAR vehicles?
I'll feel better with a little skidplate......
Anyway, the rubber plug has been there 3 years now,,, and still dry as a bone.



This F150 front diff oil was white like a milkshake. I put it on hot steel (heated 325°F in the oven) and it turned clear.
"They say" that if there's water in the oil it will "crackle" at 325°F (like bacon on a skillet).
It did NOT crackle.

I enjoyed my project, and my thread is a "How-to"....but.... its much easier to suck the oil out (drive a bit then repeat) than do this mod.
If you have selectable 4wd your front diff is just "along for the ride" anyway and probably won't accumulate even 1,000 miles.
So one oil change (if at all) is probably REAL good.
UNLESS it's got water in there.......

Here's a simple suction rig made from a 5-gal pail with a lid. You can use a shopvac or any vacuum cleaner for the suction.

That white stuff is weird stuff. I'd still like to know what's going on there.
It's strange that there's no FORD service bulletin on this.

 

Loving these Valvoline guys. They are flushing it and said they will keep a cup of the fluid to see if it separates. Then I can come back in a few days and they will check the level and color for free.



Not bad for $108 with tax.

local shop near me says book time is 4.9 hours if I want to remove the cover

 

you got the steal of a lifetime. you can't just remove the front diff plate on our trucks without removing other things first (stupid design). see the photo above. good luck.

 

that was a drain and fill of course.
they filled it three times and just kept sucking it out. Yes ideally I would’ve driven it but they said to drive 50-100 miles and come back so they can check again.

with this type of differential do I need it in 4A or 4H to mix it up?

 

Went back today and looked at the cup of fluid they kept.

it separated.

about 60% thick grey ugly and 40% actually looking like oil (even though I expected it to be greener).

4A and 4H seem to work just fine.

hopefully not failed clutch packs. Not sure how I can be getting water intrusion, if that’s it. I do have the usual front axle seal weep and use automated car wash.

vent hose is good condition and routed properly.

 

Yes of course.
If the truck is in 2wd the front diff does not turn.

------> (I don't know anything about the 4A system)