rear end locking up while turning

[craigroyse]

Hello. I wasn't sure where to post this so I'm posting it here. I have a 2003 E-350 with the 5.4l triton and my rear end is locking when I take off from a stop and turn. I pulled the drain plug and dipped my finger in there and the oil is brown with a BUNCH of metal flake in it. And the consistency is like water almost. I pretty much figured I got to replace something.

I'M NOT SURE WHAT REAR END I HAVE THOUGH... The tag says PN: 6756-2 and underneath that is says 8001PBRE04PM. On the back of the differential is engraved:

42815
268 2
Rev V
07 06 98

Some help would be nice.

[Pullnpray]

well metal shavings are never good, that is indication that your gears are grinding. try first pulling the differential cover, giving it a good cleaning WITHOUT water. and then adding new oil and the posi additive. if it doesnt help, you may be in need of a new rear end...but start off with the cheaper method!

[dazdillenger]

Where are you located? The local yard has a really really clean e350 shuttle bus for parts, 88k on it. It's a u-pull it, so should be cheap (100 bucks or so!)

[craigroyse]

I'm from Kansas. I had my mechanic buddy of mine pull the cover off and he said the oil was pretty clean and theres going to be a little metal flake in it from metal to metal contact. he said as the gears wear there will be metal in it. He sealed up the cover and going to add the motorcraft synthetic 75w140 oil and 8 oz. friction modifier and see how it does. I'll let you know later in the day how that worked.

[craigroyse]

I put the new fluid in with the friction modifier. At first it didn't seem to change anything. I went out in the parking lot and did figure 8's for like 10 minutes. I don't think it changed a thing. The next morning I got up and drove my van and all morning it didn't lock up. It's been about 20 degrees in the morning and I think the oil being thicker helped it out. And it seems like everyday it gets better and better.