Rear Differential FLuid Change

[dloldham]

Hi all, I'm planning on doing my own rear diff change for the first time, and wanted to run something by the experts before I got started. I have a 97 Mountaineer, with the 3.73 rear gears. After the fluid has been drained, and I'm ready to put the Diff cover back on, do I need to use RTV sealant AND a new gasket? My research has shown that some people use gasket only, some use RTV sealant only, and some use both. Any input on the preferable method?

Thanks in advance.

Don

 

[Maniak]

Its personal preference.. I haven't used the paper gasket in a long time.. I use "right stuff".. its black and comes in a chease wiz looking can (also comes in a small caulk gun looking tube)...

One tip.. Open the FILL plug first.. BEFORE you take the cover off.. There is nothing worse than getting everything done and then finding out you CAN'T get the fill plug out.

~Mark

 

[TrevoJreal429]

I also used " right stuff " on my explorer and bronco and it has been working great for a few years.
Just be sure to get quality sealant because the oil will break down the cheap stuff over time.

 

[HahnsB2]

I use RTV only, I also use the cheese whiz stuff, those cans are awesome.

 

[gavin]

I've always used only RTV

 

[aldive]

I've always used only RTV

Same here and never had any issues.

One other suggestion: be sure you can remove the fill hole plug prior to removing the over.

Good luck ....

 

[snoborder42]

Be sure you can remove the fill hole plug prior to removing the over.

X2!!!
No point in getting the fluid out if you can't get the new stuff back in.

I too only used RTV and haven't had any issues with it. Did the same thing on my dad's F150 with the same results.

 

[dloldham]

Thanks so much for the info. It seems the consensus is no gasket needed, RTV sealant should do the trick.

Did some poking around today and the fill plug seems like its in a tough spot. There is a shield protecting the gas tank that gets in the way of an easy plug removal.

 

[gavin]

it's not too hard getting the plug out; it's getting the new lube in
I think I used a 3" extension, and was easy enough to remove.

 

[Maniak]

it's not too hard getting the plug out; it's getting the new lube in
I think I used a 3" extension, and was easy enough to remove.

x2.. getting the fluid in is the hard part..

If you have a little extra cash around and wouldn't mind some bling (doesn't have to be shiny).. pick up a rockcrusher diff cover.. The fill plug is actually on the cover..

You pull the factory fill plug.. fill it through the new fill plug on the cover and when it comes out the factory plug your full..

I got mine from JTsmith here on the board.. powdercoated black and bright green..
EDIT: found pic of my cover..

~Mark

 

[dloldham]

Thanks!!

Thanks for all the help, definitely appreciate it! I changed the rear diff fluid yesterday, and the transfer case fluid, and couldnt have done it without the info from this board. Next up is trying to figure out the front diff, which is difficult on a gravel driveway with no way to lift it. May just use one of those fluid pumps and get out what i can that way.

Now im comfortable with getting the diff cover off, i think im going to throw a mag-hytec cover on my f150!

Thanks!!

 

[mountainerexpo97]

Hey i bet my trucks is due did u use any additives or special fluid i was thinking royal purple what weight di du use

 

[gavin]

Hey i bet my trucks is due did u use any additives or special fluid i was thinking royal purple what weight di du use

additive is not required unless you have a limited slip. Even then, it may not be necessary if you use a full synthetic, as they *generally* do not require the use of LSD additive.
Royal Purple does not need the additive. I used some 80w90 and 75w140 in my rear axle, which had the OEM LSD, and I used no extra LSD additive.

 

[explorernoobie]

sorry to take this topic but i too need to change the fluid in front and back. how do i do it? whay fluids do i use to refill and how do i refill?

 

[drdoom]

sorry to take this topic but i too need to change the fluid in front and back. how do i do it? whay fluids do i use to refill and how do i refill?

Check the stickies on the transmission/t-case/differential sub-forum page...many excellent how-to threads. Enjoy!