Just wondering if anyone had good tips on how to change front and rear differential fluid? I have a 2006 F-150 with 5.4. Im new at working on my truck so I could use any help that you guys can give me. Also does my truck have a drain plug or do you just unbolt the case?

 

front should have a drain plug I believe. Rear just remove the rear cover and let drain. clean both the diff mounting surface and the cover, apply silicone to the cover and reinstall. Make sure when you add the rear end fluid that you add friction modifier to it if it's a limited slip(go to your dealer parts dept and ask if you need a special modifier fluid for you rear diff). If you don't put it in and you have a limited slip, you'll blow out your clutch packs........

 

I just changed mine - front and rear so here's my opinion (4.6l, V8, SCab - 2004 New body Style)

First: Make sure you can loosen the filler plugs on both front and rear before you start. I found the front very tight and had to use an impact gun to break it free.

Remove spare tire to give better access to rear diff. You'll need something to catch the old gear oil, once all the bolts are out use a small flat plaster knife to slide inbetween the cover and diff and gently pry apart (I wore chemical resistant gloves for this process also), trying to not pull cover off completely, starting at the bottom.

Once the bottom is pryed open all the gear oil will flow out into your container. Then remove cover completely. Clean cover with brake cleaner and use plaster knife to get most of the gasket material off. My diff had some fluid left in the bottom in a small well so I used some clean rags to soak it up. I then used a wire brush to get the remainder of the gasket material off and brake cleaner to wipe it down.

I used the same process to get the gasket material off the diff, placing a clean rag over the diff to prevent any gasket material from falling on it. Make sure all the old gasket is off as you don't want it to not seal and have to redo it.

I purchased the silicone RTV from Ford. You only need to use a 1/8" bead around the diff cover (don't use anymore or you risk getting it into the diff). Going on the inside of the bolt holes. Do not put any on the bolts or in the holes on the diff. Let stand for 5 mins and then place cover on using a bolt on the top hole to hold in place. Once all bolts are in torque to spec using a star pattern. Let dry at least one hour. I waited over night before I put the fluid back in. You'll need a transfer pump to get the fluid in and have something to catch the drips. Check your manual for correct amount of fluid.

The front is the same proceedure except I found it tighter to work as the steering rack goes along the front diff cover. I also had to remove the oil catch tray before removing the cover. The top three bolts were the hardest to get at but it's do-able with a small ratchet. Make sure to torque bolts to spec. and let silicone dry before replacing fluid. Check owners manual for correct amount.

Hope this helps,

Krazy

 

Now you got me wondering, I thought the diffs were filled with syn and were only to be replaced if it was submerged under water? I need to look in the manual I guess.

 

Common FlanMAN you got answers where r u to reply!? 442w30 Makes a good point, check the manual Flanman to see if it suggest not replacing fluid

 

I have been driving for 45 years and the only thing I have ever changed the differential oil in is my motorcycles. I have never had problems with differentials.

 

I think changing the differential fluid is good habbits. Overtime, like any kind of oil, its going to begin to break down and not have as much as an ability to properly lubricate the gearing. Also, loose contaminates and metal shavings from extended mileage can begin to grind away at the gears and could ultimately cause permanent damage. So, I think it is necessary to do differential fluid changes every other transmission flush would be a good rule of thumb to me (about every 50,000 miles).

 

All lubricating fluids wear out. The anti-foaming additives in gear lube are the first to go.
When they are gone the gear lube can not properly lubricate the bearings and gears leading to premature wear causing excessive gearlash. Dan.

 

If you have a limited slip differential the clutch pack seem to wear enough that the fluid is contaminated with fine metal. It should not harm anything to change the fluid.