Rear differential question???

[carguy75]

Today i tried to remove my old rear differential fuid in my 2011 Ford Edgw AWD.

 

When I open the fill plug a lot of old fluid flowed out of the filler hole.

 

After the old fluid slowed coming out of the filler hole I tried removing some more fluid and got a bit more when using a fluid extractor.

 

When I tried pumping in new Royal Purple 7W-90 gear oil in the fill hole is started to flow out of the filler hole after just a couple pumps or less that 1/4 bottle of gear oil.

 

Do I have to just remove the cover to get all the old fluid out of the differential or do i have to suck some more of the old fluid out of the filler hole and wait and try to remove more fluid over and over for a few times to get out all the old fluid?

 

Are the Ford Edges differentials over-filled from the factory?

 

The way the old fluid first came out of the fill-hole had me thinking that that I removed a drain-plug instead of a fill-plug.

 

I will most likely just pulled the diff-cover and let all the fluid just drain out and just replace it will new RP fluid since I guess I have about 3/4 old Ford 80w-90 fluid and 1/4 RP 75w-90 fluid in my rear differential now.

 

Good news is that the Ford 80w-90 fluid look new so I guess that my rear differential is doing ok so far at 27K miles.

 

This is the first car that I had that had so much old differential fluid flowing out the filler hole, all the other cars will have some seep out

but not nearly a 1/4 quart of fluid drain out.

 

Again is that normal for our cars?

 

If so, how do they get so much fluid in the differential.

 

The vent port on top of the differential?

Edited July 22, 2015 by carguy75

[akirby]

Was the differential hot or cold? When hot the fluid will expand.

 

But why are you changing it at 27K? I don't recall any problems with the rear diff that would warrant early fluid changes.

[carguy75]

To be honest, i read some different threads in various Ford forums that recommeded that the fluid be changed at 30k miles or so.

 

I actually was looking up the PTU fluid, but got some information regarding the different AWD models across the board with the PTU and rear differentials.

 

Most threads recommeded the fluid be changed sooner than what Ford recommeded for normal use, but most of the cars were pre-2011 models which had a different AWD set-up than the new AWD used in my Edge.

 

So maybe the fluid is better in the 2011 modesl now.

 

To be honest the fluid was a perfect looking honey color, so I do not think that we really have to change it in the Edge until much later.

 

But my rear diff-unit was over-filled, which could cause other damage from what I have read about over filled rear differential units.

 

So I am glad that I checked mine.

 

The car was not cold, but it sat for a few hours before i changed the fluid so I believe that my unit could have been over-filled at the factory.

 

I am still not very sure about this one(hence my post), but a lot of fluid flowed out of the fill-hole(more than what i added today with the RP).

 

However, i will still just finish the job by pulling the cover and replace all(most) the fluid with RP differential fluid.

 

I was just too lazy to deal with making a new diff-cover gasket today.

 

To be honest i think i gave myself more work to do that was not even needed.

 

I should have just let the excess old fluid drain out from the fill hole and left well enough alone.

 

Well I have always used RP 75w-90 in my rear diffs as habit, but on the Edge it may be just over-kill since my car rarely ever provide power to the rear wheels.

Edited July 23, 2015 by carguy75

[carguy75]

Well today I finished the rear differential fluid swap.

 

Next time I will just suck out the old RP fluid and fill it with new fluid without removing the diff cover.

 

I will not be messing with it until maybe 60k miles since the rear axle does not get hardly any power from the PTU.

 

Next will be a PTU fluid change, but I will have to do that one every 30k miles to be sure since i heard some bad rumors about the PTU life expectancy when going too long on old fluid.

 

It looked like my rear differential was over-filled some how, but I am not surprised since I have read that other Ford owners have had the same thing happen to their cars from the factory.

 

http://www.allfordmustangs.com/forums/2011-2014-mustang-gt-tech/263401-rear-differential-overfilled-leaking-breather.html

Edited July 29, 2015 by carguy75

[WWWPerfA_ZN0W]

Agreed. All the guidance on the PTU/RDU fluids has come from owners, so empirical data is our friend right now.

[carguy75]

Agreed. All the guidance on the PTU/RDU fluids has come from owners, so empirical data is our friend right now.

I have learned over the years to listen to the owners more than the manufacturers when it comes to reliability of certain components.

 

Hence, when a large number of owners complain about a certain part or component failing I listen and try to do the recommended preventive measures if posted.

 

I have owned many cars from Pontiac to Mercedes over the years, and have found the owners are usually always right.

 

Hell, the customer complaints listed in forums usually become service bulletins, recalls, or better yet extended warranty coverages issued by the manufacturers when they admit that there is a problem.

 

I used to be like most people that read complaints on forums and say that the people are just complaining because my car is not doing that, but soon after my car usually gets one of the talked about problems and I feel like fool because i read that is could happen but I followed the manufacturer recommended service instead(2001 Volvo S80 T6 automatic transmission failure that could have been prevented by changing the fluid earlier than what Volvo recommended in my case for one example).

 

However, I have now been very proactive and do preventive measures on issues that can be avoided with additional maintenance and have had less problems over the years with my cars.

Edited July 31, 2015 by carguy75