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evh

Rear Differential fluid change procedure

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My 2009 has 100K miles on it now. I also plan to start towing a boat that is close to 3,500lbs. I want to change the rear fluid. I read the manual and we are looking at 2.4 pints of 80/90. I have a vacuum device that will "suck" most of the fluid out (I hope). Does anyone know the correct fluid level in the rear diff? Should you fill to overflow? Fill to a half inch below the top, etc. I will measure where it is at once I open it. But I would like to know the "official" level.

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OK. I changed the fluid, here is what I found.:

 

I bought two quarts of Valvoline 80W90 gear oil. $4.99 a quart (that is what the manual says to use on my 2009 Limited AWD). I raised the vehicle up about 4 inches (level). Made it easier to get under. Let me comment on an easy way to do this. Grab a 2x6. Cut 4 3' lengths and 4 2' lengths. Screw the shorter ones on top of one end of the longer ones. Use a saw and taper the ends of each. There you have 4 ramps that are easy to drive up on. Put one in front of each tire. Drive up. Very solid.

 

I then removed the plug using a 3/8" drive socket wrench. I took a small zip tie, bent the end at 90 degrees and stuck it in the hole. Looks to me like it was filled right to the top of the hole. Good news, it will be easy to tell when to stop when I am filling it. I have access to a vacuum sucker thingy. Common at marinas for sucking fluids (oils, etc.) out of places without drain plugs. Took a while (20 minutes) because the oil was so think. The manual says it holds 2.4 pints (2 pints to a quart). I think I got close to a quart out. The vacuum sucker thingy uses clear tubing so I could watch the oil drain. You have to keep pulling out the end of the hose and re-positioned it. Note, the oil looked quite clean.

 

I then snipped off the end of a new quart. I had another chunk of clear tubing. Put it on the new oil. Had my son squeeze the oil while I held the other end it. Note, this is also a lengthy process since the oil is so thick. The easier job is holding the end in the differential, you get tired of squeezing the oil (we switched jobs half way through). You also laugh when the tube comes off the end and fresh oil squirts out. Another reason to buy two quarts. Once it was filled, I cleaned off the plug (note it is magnetic) and re-installed.

 

I have attached a picture of the differential highlighting the drain plug for those that like visuals. Not a terribly tough procedure.

Edited by evh
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Here is the picture.

 

post-9254-0-09610000-1312641247_thumb.jpg

 

 

 

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Update:

 

If you read the beginning of this post, you will see I replaced the rear differential fluid in my 2009 Edge on August of 2011 with about 83,000 miles on it.  7 1/2 years later I still own the Edge and it has 225,000 miles on it.  Figured I would change it again.  I was surprised at how clean the gear oil was.  The fill plug has a magnet on it and there was not much stuck to it.  Simply sharing.

 

Who knows, maybe it wasn't that clean but a few weeks ago I was trying to change the fluid in my PTU.  Black sludge.....l  

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5 hours ago, evh said:

 I was surprised at how clean the gear oil was.  The fill plug has a magnet on it and there was not much stuck to it.  Simply sharing.

 

Who knows, maybe it wasn't that clean but a few weeks ago I was trying to change the fluid in my PTU.  Black sludge.....l  

I hope our Edge fares as well. Was there more you wanted to add after black sludge?

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10 hours ago, evh said:

Update:

 

If you read the beginning of this post, you will see I replaced the rear differential fluid in my 2009 Edge on August of 2011 with about 83,000 miles on it.  7 1/2 years later I still own the Edge and it has 225,000 miles on it.  Figured I would change it again.  I was surprised at how clean the gear oil was.  The fill plug has a magnet on it and there was not much stuck to it.  Simply sharing.

 

Who knows, maybe it wasn't that clean but a few weeks ago I was trying to change the fluid in my PTU.  Black sludge.....l  

If that's the case, the PTU has most likely suffered as a result, ......... but hard to predict how badly, or what life is left in it.

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Perhaps they meant lifetime rear differential fluid and PTU not so much. :)

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13 hours ago, pintokid said:

I hope our Edge fares as well. Was there more you wanted to add after black sludge?

Sure, here's the story.

 

When I got the Edge in 2010 with roughly 65,000 miles on it, I did my research and found all the posts regarding the PTU.  I looked under mine and saw what I thought was a little weeping from it.  Panic!!!

The deal I got on it came with a special warranty so I took it to the dealer and they put new seals (I think) in it and I was good to go.  Well, if they did that, they had to put new fluid in it.  So lets assume we had new fluid at 65,000.

 

Role forward to today.  It is has now been on the road for 10 years and has 225,000 miles on it.  I have had no issue with the PTU and done nothing to it.  I want to keep the car for quite a bit longer and decided I should do something, but what???  Well, I have read all (well many of them) of the threads on the PTU and seen the cut away pictures of bad ones.

 

I spoke to a number of "experts and got mixed feedback.  So here was my thinking:

 

I could drill a hole in the bottom and but a plug in to help support draining and filling, but I really don't want to do that.  If I screw that up, then then I am worse off then before.  Not my cup of tea.

 

I have one of those Might Vac suction devices for extracting fluids (note, if you don't have one of those, consider getting one).  So I thought about introducing some type of fluid to break up the black sludge and then vacuum it out.  All of my experts advised against it.

 

One expert said to do nothing and was treating it like a transmission that has never had service.  Thinking that if you change fluids now, you could introduce a problem.  That the gunk was keeping it working and new fluid may cause an issue.  I have a hard time with that logic.

 

Another expert advised to simply do a number of drain and fills using the correct fluid and because of the Mighty Vac, I can do that.  So with the temperature in Michigan at 25 degrees (worse timing ever), I started. 

 

The plug on our PTU's has a magnet and it was covered with gunk.  I used a zip tie and stuck in down in the hole to see what I had.  The level was way down and it was truly black sludge.  What I expected give the age and mileage.  The low volume didn't concern me too much because I saw no signs of leaks.  My assumption is the quantity of fluid in there was correct but it has stuck everywhere and doesn't drain back down.   

 

I used the mighty vac and tried to suck some out.  It probably got a tablespoon out.  Too gunked up.

 

So, I got some 100% synthetic 75W-140 and pumped in 7 squirts of new fluid.  Maybe an ounce or two.  I did not fill it and I did not want to.  I don't want it hurting the seals or have it pumping out the vent.

 

Next week we are supposed to have a day in the 60's.  I will get back under there and try to suck some more out and hopefully replace it  with a bit more than 7 pumps.  I will do this 3 or 4 times and see if I can see progress in breaking up and removing the gunk. 

 

 

 

 

 

 

 

 

 

 

 

 

Edited by evh
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I drilled a hole in the bottom of the PTU and did a drain and fill about 6 times (drain/fill/drive a bit) to flush the old black sludge out. Once I used transmission fluid as a solvent. Still getting some sludge out but it is becoming less and less. Now I only use the 75W140 and each time I filled it to the fill hole level. Now the fluid is staying cleaner. 

Mine was also quite low when I first stated this but am confident that filling it to the bottom of the fill hole is the right thing to do. I don't have any leaks or any puking out the vent either. 

I also got a used PTU from a tranny shop just so I could take it apart to see what is inside - just gears and LOTS of sludge. I change my PTU oil (myself) every 2nd engine oil change. Initially before I put in the drain, I tried sucking out the old fluid but had a really hard time getting the sucker hose far enough inside the PTU fill hole.  Even sucking a bit out and topping it up with clean oil has to be better than just leaving the old black sludge in it. I always remember that it's cheaper to change oil than parts! 

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For all you non-DIY ers (me mostly), I went to my local Firestone and had both the PTU and RDU drained/refilled. They used their powered pump and had both units fluids changed out in 30 minutes total from driving in to leaving. Cost $197.  Same 75-140 for PTU and 80-90 for RDU.  Both reservoirs are small so don't use more than appx 1/2 qt apiece.

 

Yes you can save all the labor charges by changing your own RDU fluid as was posted above. I'm old and lazy so I didn't. 

I think that will do it for the RDU  (it has 55K, shouldn't need anything else) and I'll keep the PTU changes about every 25-30K (same as coolant).

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