Changed diff fluid on my 05 F150 4x4 last week. Filled it with Lucas Syn 75W-140 and Motorcraft FM and decided to check the level today after driving it and when I pulled the plug I had a foamy fluid running out. That tells me it's low on fluid and getting too hot. I believe I need to let it set for several hours and top it off. Does this sound correct?

 

how much did you put in when you changed it?

 

Foaming could be the result of over filling!

 

Especially if one's over-filled themselves with Schell's Dark beer.

 

No beer but maybe a glass of wine! I can't get my truck level since my drive has a slight incline to it. I backed it in so the rear was close to level, let it set and hour and rechecked the fluid. It's clear like it's suppose to be and no fluid running out. I put my pinkey in and the fluid was just below the lip of the hole. As near as I can tell I put 88 oz in it. That's including FM.

 

Its a open system.....meaning it has a breather, the ring gear moves up.....fluid and air mix in a open system so yea my thoughts it will foam up. A brake/cooling system is closed so it shouldnt have air in it.

 

Thanks for all the good advice. I guess I'll run with it.

 

How foamy is foamy? You may have a little water in there. Did you clean the diff gears when you popped the cover off? If so, what did you use to clean it?

 

Was wondering the same thing about what may have been used to clean with.

I serviced the rear diff in my truck a couple of months ago and remember reading about how solvents, if all residual is not removed, can compromise the new lubricant's properties.

So, I didnt use anything but rags and elbow grease and cleaned every freakin tooth in there one at a time.

Had I not read about that, Im sure Ida used brake cleaner or something similar.

 

Is the vent blocked . Or has it been under water in a mud hole ,don't like this foamy symptom . Me I would redo it after checking vent , mudders run their vents up into glove box on some vehicles.
They also jack up fill side so they can get extra fluid in it .