My '05 has rust in the rear differential cover. The differential is painted black from the factory, but the paint is flaking off and rust is emerging.

The truck lives in Phoenix, Arizona and has barely 24,000 miles. I am a bit disappointed because looks like Mr. Ford forgot to dip the metal part in anti-corrosion bath. There is no rust anywhere else, just the differential cover.

Is there a chance that the Ford dealership might fix this under warranty? I can brush and repaint, but wouldn't like to be doing this every year.

 

How does the fluid look in the rear end? Sometimes when rear ends have problems they can heat the fluid so much it bakes off the paint allowing rust.

 

clean it up then use rattle bottle paint spray (high temp) simple

YOMAN!

 

Mine is starting to rust as well. Mine is a 2005 with about 31K on the odometer.

 

Rust on the outside, I wouldn't worry much about it...it happens.

 

Same here - on an '06 after one winter.

1. Paint it
2. Mag-Hytec.

 

People sometimes forget that it's Ford Motor Company -- not Chip Foose!

The factory does not spend a lot of time or money worrying about what the undercarriage looks like after some exposure. As long as it performs its intended function, you're probably out-of-luck with it as a warranty issue.....

 

Mine is a 2005 and its starting to rust too so I guess thats the norm for these trucks.

 

I know a guy on a construction site who uses a F-350, for work, company truck, he commutes all the way down from Maine, to get to the site, I noticed a while back that his diff cover was really rusted, probably from ME winters, then I noticed that the rear diff cover factory sticker & all, was new one day, cannot miss them on a F-350, so high, I asked him about it, he stated that it almost rusted through, & got it replaced under warantee.........

 

I have what looks like a small leak driping onto the top of my rear diff. cover. Or maybe the rear diff cover itself is leaking. Either way it looks strange to me that the underside of my truck looks dry as a bone except for some greasy looking streak on the back of my rear diff. It doesn't ever look fresh, so I'm wondering what is going on. Anyone else notice this on theirs?

 

Few things here.

First the rear end housing and axle tubes are made of iron, nothing you can do other than clean and paint them but they will rust, warrantee will not cover it, and unless it gets really bad it will not cause a problem. My Mach had a nice layer of rust all over the housing and tubes after it was 4 months old, it is now going on 4 the rust has not gotten any worse and that is spending all its time in 90%+ humidity all day every day, well except for the 35 or so days of so called winter we have.

For the leak on the cover, you might want to feel around on the top of the housing they usually will have a vent up there that from time to time will spit out some fluid.

 

I agree with a previous poster - get the finned MagHytec cover. You won't regret it. It increases the rear oil capacity, adds a dipstick, temperature sensor sending unit port and drain plug. Nice product.

Attached are a couple of pics I took of my old cover and tags as I was removing them. There is little doubt that heat caused the paint to bake off. You can even see where the black paint baked off the tags!


http://i31.photobucket.com/albums/c3...n/IM002081.jpg

http://i31.photobucket.com/albums/c3...n/IM002082.jpg

 

When mine started showing a few rusty pitting marks, I just pressure washed underneath (it was pretty clean anyway), and went at it with a can of flat black Tremclad, and touched up a few other areas while I was under there. This was back in March, we still had salt on the roads and a couple of snowfalls since, and to this day all I do is run a pressure washer over the rear axle/diff area once in a while and the truck still looks like it's new. I get that all the time from people thinking it's still brand new. It now has 37,000 km's on it.
The Tremclad's great. When the time comes again, I'll just give it another shot with the Tremclad, if I ever have to

 

Oh, one more thing. I didn't even use the high heat Tremclad. I just used their regular ole rust paint.
I've used the same paint on the calipers for the Mustang and they still look great two seasons later. The heat hasn't bothered it at all.
Diffs don't get all that hot anyway.

 

I went out and bought about 10 cans of rattle bottle spray paint, and I spent 1/2 day completely painting the underbody of my F150 with Rustoleum Industrial High Gloss Black Spray Paint. I did this about 8 months ago, and it's holding up VERY well.

I plan on cleaning the underbody well one of these days and spray it again. Just to make sure it is well coated. It can't hurt... not to mention the underbody repels a lot of road gunk.