Rear differential Leak

[EricLNC]

my 2007 Expedition EL with 5.4 V8 recently started showing some drops on the driveway. About 10 spots over the last couple weeks. I can see droplets forming on the rear differential housing. Anyone have experience with this leak? how soon shoud I address it? I have 216K miles and thinking of replacing but want to know if this will expedite its demise or if I can continue to drive as a daily for a few more weeks?

 

[Hamfisted]

You can drive it, as long as you verify the fluid level in the differential is full. Get a 3/8 ratchet and take the fill plug out and check the oil level. Get a quart of 75w-140 synthetic gear oil at any autoparts store and a big syringe with a tube on it to bring the fluid level up to the fill plug hole. Typically it's the side shaft seals leaking. Do you have a shop in your area that does this kind of seal replacement work ?













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[eddytheexpy]

Well, if you're not really looking for a true fix, but more of something to keep you on the road for the foreseeable future, here's the stop-gap solution I'd do. Just change the diff oil so you know it's topped up and then just keep topping it off. After a couple top-offs you can characterize the leak rate and just stick to that schedule.

Also, when you do the initial gear oil change, you can get a picture of the general health of the diff by how much metal is on the magnet of the drain plug and by how much gear oil comes out since it's probably been leaking for a while and you're just now noticing/caring about it.

As for how soon to address it, I'd say address it today. If you haven't done a gear oil change before, it's super quick and easy. I'm talking like under 20 minutes start-to-finish, so you'll spend more time running to auto zone for the gear oil and thread sealant for the plugs. BTW, take your rig to auto zone when you are picking up the new oil so the diff warms up and the oil flows out better when you get home.

If you have a limited slip diff (or don't know if you do) let me save you some time if you haven't done this before. Just get the valvoline gear oil at auto zone, it has the friction modifier already it. The friction modifier won't hurt an open diff but it's needed for the limited slip diff. So it just takes out the guess work.

 

[Tractmec]

I have one more thing you should check and you will have to crawl underneath(you will have to do this to check the oi level any way) and get dirty and do a an Arm snake into a tight area above the Diff.

On top of the Diff there is a short rubber Breather hose on a fluted fitting. This adapter can get plugged with debris and the diff will not breath during heat up and cool down and the pressure in the diff will build up and force oil out the seals(usually out the half shaft seals first)!

It is tight and you can only get one hand/arm in there( do this with everything cold as you will be close to the exhaust, the rubber hose comes off and goes on fairly easy once you get a hand in there) and you will need a fine stiff wire to push through the fitting to make sure it is clean!

Check and fill the oil as per above replies and do this breather fitting clean before doing anything else drastic! If you are only getting some drops on the drive way at this point you may be able to stop it in it's tracks by just cleaning the Breather!