Two days ago I changed my rear outer and inner wheel bearings. I had one that was really trashed and the seal was broken. You can see the damage in this post.
https://www.ford-trucks.com/forums/1...l#post12585793

After getting a taste of how bad my rear end fluid was I decided to drop the cover on the differential and change it also. I was really in no mood for photos but I did get a couple and am concerned if this is normal.

Here are the gears - see the score marks? I don't know what these parts are even called but is this normal or should I start tossing my quarters in the penny jar for new gears?


Here is the fluid. I can put my common sense hat on and determine that the mechanic who installed my rear axle housing and said he changed this fluid in July (1,500 on it since then) is full of donkey dung, but for those of you have changed fluid before - how many miles you think this fluid has on it? Looks a lot like the runoff from washing off grinded rust residue when I did the underside of this truck this summer. But maybe this is normal, thinking NOT, any chance this really is fluid with 1500 miles on it!?


Truck was making some rear end noise before the bearings and fluid change, I think mostly from the bearings and that is now pretty much gone. I say "pretty much" because I have only taken it for two short test drives since both were done. Road tripping to pick up some kids from college this afternoon and will get a better feel for the sound.

 

It's hard to say but based on the pic is say a long time. Most people never change it. Mine was an ugly brown when I changed mine and I have no clue when mine was done prior to that

 

The marks on the carrier are from the pinion bearings being bad and the pinion shaft coming into contact with the carrier. I suspect you have had the pinion bearings replaced so you have nothing to worry about. As far as the fluid its hard to tell on how long its been in there, if they didnt flush out the housing when the did the bearings in could be residual color from the old fluid that was in there.

 

From what I can tell, it looks like my 96 F350 when I had it apart, and had to have it re-built that is from your pinion gear going back and forth (front to back) and rubbing on the ring carrier. Do you notice some slop/slack when gassing or coasting? Maybe a slight vibration on take-off or landing
But, from what I can see, it looks the same as mine.

 

It was a replacement axle and I don't know it's full history but I'm guessing that is case because there is no scoring at all on the pinion gears so whatever made those it is not what's in there now at least as far as I could tell. When I looked closely at the gears (I think those are called pinoin gears the left side of my picture) I can't find any gouging or marks that would have made the groves in the carrier.

No actually I don't have any strange symptoms from the rear now, I did have bad wheel bearings and those were changed the day before I did the fluid and took these pictures. I have no take off or landing vibration. Did have a high speed sound and some high speed vibs over 60 on the highway but that is gone after the bearings.

So hoping that whatever caused those groves has already been fixed - well crossing fingers anyway. Thanks to you both for your information.

 

It could be majestic fluid, I know it's a redish color!

 

If you can't move your rear yoke up and down and it isn't leaking at the front of the diff and not whining those marks are from a former pinion problem. When you let off on gas the pinion gear tries to move into the ring gear but is controlled by the pinion bearings. The gear on the left is the ring gear. (ring and pinion gear-set). Intrusion of a small amount of water can make even new oil look that color.

 

No leaking - check
No play or movement in pinion - trust me I have yanked, pulled, kicked that thing shaft on and off, neutral, park all of it (during my drive shaft saga)- doesn't move.- check
Whining I did have now gone after wheel bearings replaced - check

So I think I'm good.

 

There is very litltle clearance between those 2 years and it appears to be a former loose pinion gear problem, also; bad parts=dark oil, and water=light colored oil.

 

I know how it got water into it, I bought it and it was on a trailer at this shop for several weeks before they got it installed. I know they opened up the front and serviced and checked it, I was in there and looked at the gears myself. But the rear I never saw open, they claimed they checked it and all "was good", but in reality it sat there on that trailer in the rain with the vent open, and those lazy you know whats, took it slapped it in my truck. If they had opened it one it wouldn't have had water in the fluid and two they would have seen the rebuild on those gears and probably would have told me they were shot and tried to get me to spend another $1000 rebuilding it!

Ok done venting! Thanks guys.

 

Well thought i would update since the beginning of the thread said I would get it up on the highway this afternoon on my road trip to get my boys from Purdue - very quiet enjoyable ride. All the rear end sound is gone. Amazing what a difference a rear that rolls and some fluid without water in it can make. Happy dance!

 

Curious, why was the axle (whole rear end) replaced?

Normally when one bearing goes bad in a rear end they all need to be replaced because of metal contamination.

If you replaced the entire rear end the n"new" rear end could have had pinion bearing problems in the past which caused the marks on the diff. The bad pinion bearings in the past are what ruined your wheel bearings. Very lucky the gears themselves are good yet. I would be worried about the carrier bearings now personally.

 

When I got the truck the rear axle was so rusted it wasn't usable, so I replaced the entire axle housing with an axle off an F250 2002, apparently this axle had been previously rebuilt before I bought it used. It was cheaper to just put this one in than to swap out any parts, and well I didn't know it had this scoring because the shop apparently never even opened it and looked like they told me. So if I have a problem I do still have the good internal parts from my original axle it was just the housing that was shot. I'm worried as well, but all sounds good for now.

 

Ah... previous axle rebuild, the carrier was still in good condition, just had some emotional scarring left over from the ordeal, well everyone's got baggage!
Glad to hear all is well!

 

This is part of the reason why I installed the Mag-Hytec Diff covers. With those on you can check your fluid anytime you want. And it makes changing the fluid so much easier.

A little pricey but for the piece of mind, Highly recommend...