What do I feed the Rear Diff.? *PICTURES*

[janolsson]

Hey bob
Just do another quick check while your head is under there.
Look at the filler neck for the fuel as here in the UK we have a lot of trouble with them rusting through and dumping fuel on the forecourt rather than in the tank and at about $1.5 a litre thats a costly problem. If there is a leak here the fuel could run down the outside of the filler neck and onto the outside of the tank.
Regards

 

[BobWiersema]

Hey bob
Just do another quick check while your head is under there.
Look at the filler neck for the fuel as here in the UK we have a lot of trouble with them rusting through and dumping fuel on the forecourt rather than in the tank and at about $1.5 a litre thats a costly problem. If there is a leak here the fuel could run down the outside of the filler neck and onto the outside of the tank.
Regards

I did notice that thing is getting rusty. Looks like something that should be replaced soon but for now its not leaking. I'm still trying to figure out what those guys at the dealer did with the money I gave them to undercoat this thing because they sure didn't spend it on the truck.

 

[my pos mounty]

I did notice that thing is getting rusty. Looks like something that should be replaced soon but for now its not leaking. I'm still trying to figure out what those guys at the dealer did with the money I gave them to undercoat this thing because they sure didn't spend it on the truck.

Beer money

 

[bluestream1]

I did notice that thing is getting rusty. Looks like something that should be replaced soon but for now its not leaking. I'm still trying to figure out what those guys at the dealer did with the money I gave them to undercoat this thing because they sure didn't spend it on the truck.

Bob you need to oil spray the truck to stop rust. I do it once a year, and have no rust on mine. The undercoating is just garbage. Also, at the top of the diffy, there is a steel clamp holding the brake line. That clamp holds moisture and rusts out the brake line. Open the clamp and use a zip-ty to hold the brake line. I would oil spray all of your brake lines as well Here is what I have been using:

 

[BobWiersema]

Undercoating Oil

You think that would at least stop it from getting any worse?
I did a quick search and didnt see any place to buy something like that around here. Where did you buy it. Any idea who would carry that oil in the mid-west here?

Bob

 

[96eb96]

I would get a new rear end/diff cover too if its very rusty and you are planning on keeping the truck. They are $20 at NAPA. Mine started to leak and I had to replace it.

 

[BobWiersema]

I would get a new rear end/diff cover too if its very rusty and you are planning on keeping the truck. They are $20 at NAPA. Mine started to leak and I had to replace it.

I was going to clean and paint it, but for 20 bucks Ill skip the work. And yes I am keeping the truck. For what I paid for that thing new, Im driving it until the wheel fall off. Besides the engine only has 20K on it, body is clean and rust free, just that underside rust I need to clean up.

 

[BK_89iX]

I was going to clean and paint it, but for 20 bucks Ill skip the work. And yes I am keeping the truck. For what I paid for that thing new, Im driving it until the wheel fall off. Besides the engine only has 20K on it, body is clean and rust free, just that underside rust I need to clean up.

Glad to hear it's a keeper! How many miles on the chassis? If you're going to open up the differential to reseal/replace the cover, and also do the pinion seal, now would be a great time to replace the limited-slip clutch pack, rear axle seals and u-joints. Parking brake shoes/hardware will also never be easier to reach with the axles out. It's a slippery slope....

BK

 

[rhauf]

the moisture on the fuel tank could just be moisture or something.. i'd probably get my head in there and smell it to see if it smells like gas.

 

[bluestream1]

Try calling an oil distributor to see if they carry undercoating oil. You can use regular oil, but it is going to drip for a few weeks and can be messy I pay $18 for a gallon, and use about 2 quarts each year on it. You also need a spray gun for about $12 (harbor Freight?)

 

[gmanpaint]

Changing that pinion seal requires gutting the diff. That is a heck of a job to do if you have never done it before, one best left to the pros or someone that has at least some experience doing it.

While it is apart, replacing the axle seals, wheel bearings, e-brake hardware and shoes, rear brake pads, rotors(new or cut), and most importantly....buy a new pinion shaft bolt! Do not re-use the shaft bolt......ever! They have stress cracks, and snap in half if you try to use again, only $3 for new.

One more thing, make sure the inside of the diff is cleaned out real good and a magnet is ran in it, to remove any metal. There is a small "Catch tray" on the bottom of the diff that will hold offending items when sitting still, but gets churned up while moving.

Here is what I found in mine AFTER a shop worked on mine, and I did more work on it a few months later. They did not clean it out while working in it.

 

[BobWiersema]

Service Procedure

Changing that pinion seal requires gutting the diff. That is a heck of a job to do if you have never done it before, one best left to the pros or someone that has at least some experience doing it.

While it is apart, replacing the axle seals, wheel bearings, e-brake hardware and shoes, rear brake pads, rotors(new or cut), and most importantly....buy a new pinion shaft bolt! Do not re-use the shaft bolt......ever! They have stress cracks, and snap in half if you try to use again, only $3 for new.

This is the service procedure I got from my Ford shop manual. Looks like a simple little job to me. Perhaps you have something different, or the shop guy was behind on his BMW payments. I have read around here and it looks like the only tough part is getting the pinion flange nut off, (torqued on by gorillas).
I have changed plenty of these thing in my life, just not on this truck yet.

Also, why in the world would I replace all those perfectly good parts? This is a 20 dollar job plus gear lube, the only thing extra I plan to do is replace the U joints.

Bob

 

[Dan Whitaker]

Make sure you can get the fill plug out before removing the diff cover. They tend to rust to the housing pretty good. If you live in the snow belt it will be impossible to remove.

 

[BobWiersema]

Parts

Make sure you can get the fill plug out before removing the diff cover. They tend to rust to the housing pretty good. If you live in the snow belt it will be impossible to remove.

Thanks, I did think of that.
Its been sprayed down twice now with liquid wrench. I hope by the time I get around to fixing this it will come out. I did find all the parts at RockAuto and they have a nice shiny new cover for $15 it looks like this.

What I don't understand is why it looks like it has a drain plug in it. Not sure what that is. What I cant find is the pinion nut, the service manual (and everyone here says not to reuse it). If this is a dealer item, I will reuse it. I also did not see any friction modifier at pep boys. I guess Ill need to go to a real parts place for that.

Bob

 

[my pos mounty]

Thats not a drain hole you see there, you can use that cover if you can't get the fill plug out.

 

[BobWiersema]

Thats not a drain hole you see there, you can use that cover if you can't get the fill plug out.

Im replacing the cover because its all rusty and I dont want to clean it. That looks like a rubber plug stuck in it. Not sure if I want that. Do you have any experience with this? Is it a threaded bung? Or just a hole?

Bob

 

[my pos mounty]

I have not personally used one. I judged my statement on the design of the cover itself. If orientated to the differential that hole would be too high to be a drain.

 

[Redneck0907]

The pinion seal is not that bad to do providing your diff is in good shape internally.. I caught the seeping just when it was starting so no damage was done to the internal parts of the diff.. To change the seal i did just as posted in the ford manual. pulled the d-shaft and the flange (B-YATCH).. after that though, just rip out the old. and tap in the new.. be sure to put some oil on the seal so it doesnt snag up.. Also while your there take a look on the back of your brake dust shields. I had to also do a wheel seal. they both managed to let go within about 2 days of each other, so i replaced all the seals at once while i had it apart. and did new bearings on the ends of the axle..(reccomended by ford manual).. then wiped out the diff a bit, and capped it back up. filled it with royal purple 75w140 and 4 oz of Motorcraft friction modifier (Ebay it $5)..

Shes been great since! Knock on wood!.. Good luck!

 

[BobWiersema]

I have not personally used one. I judged my statement on the design of the cover itself. If orientated to the differential that hole would be too high to be a drain.

I see that now, the picture is turned the wrong way. Im ordering it anyway, sure it will be fine.

 

[BobWiersema]

The pinion seal is not that bad to do providing your diff is in good shape internally.. I caught the seeping just when it was starting so no damage was done to the internal parts of the diff.. To change the seal i did just as posted in the ford manual. pulled the d-shaft and the flange (B-YATCH).. after that though, just rip out the old. and tap in the new.. be sure to put some oil on the seal so it doesnt snag up.. Also while your there take a look on the back of your brake dust shields. I had to also do a wheel seal. they both managed to let go within about 2 days of each other, so i replaced all the seals at once while i had it apart. and did new bearings on the ends of the axle..(reccomended by ford manual).. then wiped out the diff a bit, and capped it back up. filled it with royal purple 75w140 and 4 oz of Motorcraft friction modifier (Ebay it $5)..

Shes been great since! Knock on wood!.. Good luck!

Axle seals look dry, this leak is new. Just noticed it last week on the driveway. I plan to fix it before using the truck again to prevent any damage. Did you need to use a gear puller to get the pinion flange off? Just wondering, I have a nice 3 claw one if I need it.

Bob