Changing the differential fluid
Junior User
Joined: Sep 2006
Posts: 97
Likes: 0
As far contamination,when you take the cover off , you will possibly see @ the bottom of the cover a rust level, this usually means the truck sat for a long period of time. Defintely use a gasket, and on the drain plug use like a plumbers putty, thread paste or whatever to prevent a leak, I only say this cause when I did mine, I used nothing and it leaked, as you will see the factory used something as well. Good luck and dont forget to look for heavy metal particles, you should find some, but you should hope not a lot, look for the magnet.
Hotshot
Joined: Aug 2002
Posts: 12,679
Likes: 15
From: BC, Canada
From TSB 06-4-4............
AXLE FLUID REQUIREMENTS HAVE BEEN CHANGED. ALL VEHICLES BEING REPAIRED BY THIS TSB MUST HAVE REAR AXLE LUBE XY-75W140-QL INSTALLED, IN PLACE OF XY- 75W90-QFEHP. AS PART OF THIS REPAIR, CHECK AND REPLACE IF NECESSARY THE CURRENT XY-75W90-Q"FEHP" METAL TAG, WITH A NEW 75W140 TAG (F3TZ-4121-AA). ADDITIONALLY, REMOVE THE MULTI-COLORED LABEL WHICH IS LOCATED ON THE RIGHT SIDE AXLE TUBE, OR BLOCK OUT ANY/ALL "FEHP" OR "75W90" REFERENCES ON THE LABEL.
AXLE FLUID REQUIREMENTS HAVE BEEN CHANGED. ALL VEHICLES BEING REPAIRED BY THIS TSB MUST HAVE REAR AXLE LUBE XY-75W140-QL INSTALLED, IN PLACE OF XY- 75W90-QFEHP. AS PART OF THIS REPAIR, CHECK AND REPLACE IF NECESSARY THE CURRENT XY-75W90-Q"FEHP" METAL TAG, WITH A NEW 75W140 TAG (F3TZ-4121-AA). ADDITIONALLY, REMOVE THE MULTI-COLORED LABEL WHICH IS LOCATED ON THE RIGHT SIDE AXLE TUBE, OR BLOCK OUT ANY/ALL "FEHP" OR "75W90" REFERENCES ON THE LABEL.
Junior User
Joined: Jun 2006
Posts: 71
Likes: 0
From: SW MN
I changed the rear end oil in my 2000 f150 a year ago. After draining everything out, I used this special tool that mixes air with a little bit of gasoline for cleaning (you need an air compressor to use it). Is that hard on the seals. Would diesel fuel be better to use? It was an open gear rear end. So far, I have no leaks at all, but now the bearings are going out because you can move the drive shaft up and down a good amount just before it goes into the rear end. To fix that, do you have to pull the cover off and take everything out to get to it?
Hotshot
Joined: Aug 2002
Posts: 12,679
Likes: 15
From: BC, Canada
A bit of gas probably didn't hurt anything. A better cleaner to use is a solvent like Varsol.
To replace the pinion bearings you have to pretty much pull the whole rear end apart and you'll need some special tools like a press, torque wrench etc.
I'm all for guys working on their own trucks but replacing pinion bearings is something I'd recommend having someone experienced do.
To replace the pinion bearings you have to pretty much pull the whole rear end apart and you'll need some special tools like a press, torque wrench etc.
I'm all for guys working on their own trucks but replacing pinion bearings is something I'd recommend having someone experienced do.
Senior User
Joined: Sep 2004
Posts: 177
Likes: 0
From: Fort Payne, Alabama
So what is this reply about not using any cleaner inside the differential housing? How does it hurt it? I always use brake cleaner for a grease/oil cleaner, best stuff i've found, dries instantly.
New User
Joined: Nov 2006
Posts: 5
Likes: 0
From: Laveen, AZ
Originally Posted by BlueOvalFitter
Oh,one more very good tip; make sure you can remove the fill plug first before dropping the cover! I've seen them be in there very tight and not want to come out. 
Great tip on making sure that the plug will come out first.
There have been many of times that I have run into similar situations where if I would have checked one simple thing first I wouldn't be in dire straits in the end.
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Junior User
Joined: Dec 2005
Posts: 68
Likes: 0
12 bolt differential cover has no gasket. They are hard to find. I used the black rtv silicone to make a seal, then waited for it to dry for several hours before filling the differential. At the dealer service, they do the same thing. If you do get a gasket, make sure it fits before taking the old one off.
How do I know this? Did it today. Had a small leak on the bottom of the cover. Went to get a gasket, got in a hurry and drained before looking at the fit. Called the local Ford house and was told to use the black rtv which I had.
How do I know this? Did it today. Had a small leak on the bottom of the cover. Went to get a gasket, got in a hurry and drained before looking at the fit. Called the local Ford house and was told to use the black rtv which I had.
Junior User
Joined: Dec 2006
Posts: 64
Likes: 0
I just changed my differential lube and put 3 quarts of 75w140 and 4 ounces friction modifier. The parts guy said I would only use a little over 2 1/2 quarts. What is the actual differential capacity? I don't have a manual to refer to. I stuck a piece of wire in the fill hole to see where the fluid was at and it is just shy of the fill hole. I was just wondering what the actual capacity is. I put a chrome cover on and maybe that changed the capacity. Thanks everyone.
Cross-Country
Joined: Apr 2011
Posts: 61
Likes: 0
Cavity Cleaner
---i used the 75W90 synthetic instead of 75w140--- it works fine..
---the friction modifier is needed if you have limit slip rear end, when you open the cover and if you have a clutch on one side to limit the axle spin, then you need the addative.
---synthetic is very good and will last for a long time.
---dont beleive ANYTHING that says never need to drain the oil. changing the factory oil and cleaning the cavity cant hurt ANY system.
---the friction modifier is needed if you have limit slip rear end, when you open the cover and if you have a clutch on one side to limit the axle spin, then you need the addative.
---synthetic is very good and will last for a long time.
---dont beleive ANYTHING that says never need to drain the oil. changing the factory oil and cleaning the cavity cant hurt ANY system.
What should be used to clean the cavity?
