Rear differential leaking oil
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Tuned
Joined: Aug 2003
Posts: 366
Likes: 6
From: Webster, Texas
Rear differential leaking oil
I changed out the rear diff oil a while back, 30-40K ago, now at 104K. I used a Valvoline synthetic recommended here. Its strange because it ran for so long without leaking anything. It has been this way now for about 10K and obviously if not resolved something's going to go boom. Everything appears good, bolts tight, but leaking along the seam on the left bottom. I haven't tried to change out the front diff yet because it looks impossible.
Post Fiend
Joined: Feb 2006
Posts: 11,892
Likes: 2
From: Middle Tennessee
Well, appears the RTV seal has failed. Lots of help here with that dynamite diagnosis eh?
You already know you will be pulling the cover to repair it so all I can say is make sure the cover is clean and true, and use the right RTV (hi temp black). Might be a good time to get the $50 aluminum unit. I used Royal Purple in mine.
You already know you will be pulling the cover to repair it so all I can say is make sure the cover is clean and true, and use the right RTV (hi temp black). Might be a good time to get the $50 aluminum unit. I used Royal Purple in mine.
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Tuned
Joined: Aug 2003
Posts: 366
Likes: 6
From: Webster, Texas
I guess it is kind of a no brainer on that one. Maybe it just got really hot towing on vacation and melted. I don't know what brand but not Royal Purple. Is that aluminum cover a Ford dealer part?
Post Fiend
Joined: Feb 2006
Posts: 11,892
Likes: 2
From: Middle Tennessee
Originally Posted by PSDLOVER
I guess it is kind of a no brainer on that one. Maybe it just got really hot towing on vacation and melted. I don't know what brand but not Royal Purple. Is that aluminum cover a Ford dealer part?
I meant RP fluid. I used Versa Chem black RTV on mine.
Senior User
Joined: Aug 2004
Posts: 253
Likes: 0
From: Dallas GA
I replaced the pinion seal on mine when I bought it 2 years ago. Since I was at the dealership to get the seal, I went ahead and bought the diff fluid, LSD additive and Ford brand of RTV. Like Tenn said, Versa Chem's stuff is good too.
I scraped off any excess RTV and used a Scotch-Brite pad to slightly roughen surface on the diff and cover. Then I wiped down the diff and cover with acetone and applied the RTV and tighten the bolts . So far, I have not had a problem during the last 2 years.
I scraped off any excess RTV and used a Scotch-Brite pad to slightly roughen surface on the diff and cover. Then I wiped down the diff and cover with acetone and applied the RTV and tighten the bolts . So far, I have not had a problem during the last 2 years.
Lead Driver
Joined: Jan 2007
Posts: 6,708
Likes: 5
From: Kiowa CO
Originally Posted by Tenn01PSD350
Yep, looks good too. You can get them from sellers too. I don't have a link but someone will chime in on that.
Thread Starter
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Tuned
Joined: Aug 2003
Posts: 366
Likes: 6
From: Webster, Texas
Thank you guys for the solution
I need to install that new finned aluminum cover asap. Hopefully my gearing has survived. I might also consider using a different oil for the differential. It never overheated before. The factory oil and gear condition was perfect before at 70K.
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Fleet Mechanic
Joined: Feb 2005
Posts: 1,797
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From: Northern Colorado
I doubt if any amout of overheating would cause a good seal to fail and leak. Most likely there was a thin spot on the RTV seal that the oil finally worked past. 99% of a sucessful job is in the prep work. Make sure that all the sealing surfaces are clean and oil free. I have used the Valvoline syn for over a year now without any problems.
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Posting Guru
Joined: Aug 2005
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From: Central Alabama
Everyone has their own proceedures when doing things, here is mine: Make sure to use a rag to soak up the remaining fluid in the bottom of the diff. otherwise it will dribble (is seems)forever. Clean all mating surfaces with acetone, put a good solid bead of black rtv on the surface. Then wait 10 minutes or until the rtv becomes tacky, then install the cover (with the proper torque). I then wait about 30 minutes before I add fluid to insure the rtv is set-up properly. I have never had a leak doing it this way.
Elder User
Joined: Sep 2004
Posts: 780
Likes: 1
From: Chicago suburbs
Originally Posted by RAMPAGE_F350
Everyone has their own proceedures when doing things, here is mine: Make sure to use a rag to soak up the remaining fluid in the bottom of the diff. otherwise it will dribble (is seems)forever. Clean all mating surfaces with acetone, put a good solid bead of black rtv on the surface. Then wait 10 minutes or until the rtv becomes tacky, then install the cover (with the proper torque). I then wait about 30 minutes before I add fluid to insure the rtv is set-up properly. I have never had a leak doing it this way.
Now's the time to clean your cover of all the rust and paint it.
Dave
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Tuned
Joined: Aug 2003
Posts: 366
Likes: 6
From: Webster, Texas
Vent?
Originally Posted by kawika
Did you make sure the RTV went around the holes? Also is your vent clogged? With the vent clogged, you can build up some good pressure in there.
Dave
Dave
Elder User
Joined: Mar 2003
Posts: 699
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From: northern Michigan
While you are redoing the seal on the diff cover, inspect it real close, they are notorius for the OEM ones rusting through. I am on my second cover now and the truck was only 5 years old when it rusted through.
Elder User
Joined: Sep 2004
Posts: 780
Likes: 1
From: Chicago suburbs
Originally Posted by PSDLOVER
I did follow the guidelines when I did it but I am not aware of a vent. I frequently drive thru alot of dirt, mud, water you name it. We also have wasps here who's sole purpose in life is to plug every orifice possible with a mixture of dirt and saliva. Where is the vent located?
Dave
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