rear axle leaking again!

[71 SPORT]

third time i replaced the rear driver side seal and continues to leak, along with a grabbing feeling and noise when i turn.
i had my mechanic remove the pumpkin and inspect the gears and inspect the outer bearing which are both fine so he replaced the outer seal and it still leaks and same grabbing feeling and rubbing noise when i turn.I have the big bearing axle with posi (stock) any input would be greatly appreciated.

 

[DirtDonk]

Well, your grabbing feeling is about a 95% chance that it's the limited-slip differential's clutches. If it's relatively new and tight and you didn't add enough friction modifier fluid to the gear lube when it was installed, you're going to get a rear growl/grab/grunt from the back end.
Especially when going in reverse and hooking it tight.

The leaky seal could be the axle housing itself. Is your '71 still stock back there? If so, then it would have the seal inside the housing and a sealed bearing outside of it. Later models had a tapered bearing with the seal on the outside of it so the bearing would get lubed by the gear oil.
When I did mine many years ago the housing had a nick in it and allowed oil to get past the outside of the seal. I had to clean up the surface the best I could and still use a glop-o-gloop (silicone sealer) around the outside to stop it.
What condition were your axle's seal surfaces in? If they were rough or worn or pitted or rusty they may need some freshening up before running a new seal on them. Your mechanic would normally have looked at that area first, but I mention it just in case.

Good luck.

Paul

 

[71 SPORT]

Thanks for the reply,I dont know anything about diffs. It is stock with the bearing outside of the seal.I will look at the housing and check for imperfections.As far as the clutches go are they ruined now or do i just have to put in some more additive,how much is too much? The grabbing has always been there ever since i had the posi reinstalled (po had a limited slip put in) but seems to be worse now.Also we inspected the axle before the seal was installed and he said it looked to be in great shape with no seal surface wear or pitting.
I also read about installing 2 seals might try that also.

 

[DirtDonk]

Nah. Not likely ruined at all. Hardly extra wear I'd think, unless you've been driving it for a long time. In which case, yeah, some extra wear perhaps, but certainly not hopeless!
Just add a single tube/container of the stuff to begin with. 1 dose is supposed to do it, but when I had mine I had to use two tubes to get it to settle down. Just assumed that because it was a Ford Motorsport version with heavier spring preload that it needed more juice.
Later, when I switched to synthetic lube, I didn't need any additonal stuff.

Just a warning: Don't let that crap get on anything you own. It STINKS for days!!!!! So use disposable gloves and don't let any long-sleeve shirt get in the way either.
Oh, and don't breathe either, if you can help it. The taste sticks in your throat for hours. Yich!

Paul

 

[DirtDonk]

In other words... Fix the leaky seal first. Then add the Stinky Stuff.

Paul

 

[70_Steve]

Ask your mechanic if he added the limited slip additive.

From what I remember it took a couple days for the rear end to calm down after I put in the additive.

 

[Mill KNOB]

My axle seal on the driver side started leaking after 2 Months after I replace it. Then after I pull the Axles out and looking in my axle tube there was about 1/4 inch of mud and gunk in the axle tubes. So after I clean out the Axle tubes the leaks have went away. Just my 2 cents....

 

[jpopsbronco]

also possible, your housing could be tweaked.. as in bent, it depends how you drive and what you do. you said 3 new seals.. How long has it leaked for? Its plausible p.o. did something stupid and bent the housing, although its strange that its only leaking from drivers side, but mine leaks from passenger side so i guess its not so strange haha. Joe

 

[71 SPORT]

Its leaked for years finally got tired of cleaning diff fluid off the inside of my inside rim and tire
so I done it myself the first time and second.thought I wasn't doing it right so I took it to my mechanic
My 71 hasn't seen much hard core wheeling I am the 2nd owner. I am going to install this one again myself
And use some of the tips mentioned above

 

[72Sport]

Make sure the seal area on the axle has no pits in the surface. It only takes one very small one to cause a problem. Emery cloth will remove them if they are not too deep. A weld with a pit in it will cause a leak. The ends are welded onto the ends of the housings. Mine leaked where the axle tube was welded to the pumpkin.

Add another tube or bottle of friction modifier as stated above. Mine took 2 also. It took quite awhile to quit chattering.

Make sure the vent is clear. Pull the hose off and make sure it isn't plugged or kinked. Check the fitting on the pumpkin that the hose hooks up to. It is the funny bolt that holds the brake lines on the rear end. If the housing builds up pressure when it gets warm you will never stop it from leaking. I had one that was plugged so bad I had to drill the dirt/oil out of the fitting.

 

[blubuckaroo]

I've had the same reoccuring leak. One as we speak. It always seems to happen when the weather gets hot. Could I be overfilling? I fill to the bottom of the fill hole but was told that when the diff is cold to fill one knuckle deep for expansion.

 

[recoiljunky]

Make sure the seal area on the axle has no pits in the surface. It only takes one very small one to cause a problem. Emery cloth will remove them if they are not too deep. A weld with a pit in it will cause a leak. The ends are welded onto the ends of the housings. Mine leaked where the axle tube was welded to the pumpkin.

Add another tube or bottle of friction modifier as stated above. Mine took 2 also. It took quite awhile to quit chattering.

Make sure the vent is clear. Pull the hose off and make sure it isn't plugged or kinked. Check the fitting on the pumpkin that the hose hooks up to. It is the funny bolt that holds the brake lines on the rear end. If the housing builds up pressure when it gets warm you will never stop it from leaking. I had one that was plugged so bad I had to drill the dirt/oil out of the fitting.

That's good advice. The axle definitely has to vent somewhere.

 

[av bronco]

Also on mine there was a retaner tack welded to the stock axle by the bearing and the slag from the weld ate the seal.

 

[noreasteb]

Make sure the seal area on the axle has no pits in the surface. It only takes one very small one to cause a problem. Emery cloth will remove them if they are not too deep. A weld with a pit in it will cause a leak. The ends are welded onto the ends of the housings. Mine leaked where the axle tube was welded to the pumpkin.

Add another tube or bottle of friction modifier as stated above. Mine took 2 also. It took quite awhile to quit chattering.

Make sure the vent is clear. Pull the hose off and make sure it isn't plugged or kinked. Check the fitting on the pumpkin that the hose hooks up to. It is the funny bolt that holds the brake lines on the rear end. If the housing builds up pressure when it gets warm you will never stop it from leaking. I had one that was plugged so bad I had to drill the dirt/oil out of the fitting.

To this end, check the axle where the seal ride on it. My axles are both groved pretty deep from where the axle seal meets the axle after 150,000 mi or so. I've been told this could lead to leaks. Luckily nothing was leaking before I took it apart, but now I need to reassemble (finger crossed).

 

[71 SPORT]

The vent tube is clear and the seal is in good shape.
Before I remove it do you think I could get away with putting a bead of
Rtv around the edge where the housing meets the seal.

 

[malcolmzilla]

When I did my 35 spline tapered bearing conversion, I pulled the old seals, plugged the axle tubes, gently cleaned up the surface rust with some emery cloth.

Cleaned all that off with air , brake clean, cloth and more air... and then put a decent wipe of RTV silicone all throught the cup, in addtion to the integral seal on the outside of the bearing, as the cups were in bad shape, pits, holes, etc.

A bit of RTV squeezed out as I seated the new axles and bearings, let it dry overnight and filled it. No leaks so far.

 

[71 SPORT]

after further inspection of the riding surface for the seal on my axle its not grooved but is polished where the seal rides (im pretty sure they are the original axles) .Tomorrow i think i am going to leave the existing seal in, run a bead of rtv around the area where the existing seal meets the housing (on the outside),and install a second seal on top of that one so the second seal has a new riding surface.Does anybody disagree with my plan.Thanks for all the input thus far.

 

[DirtDonk]

Don't know how well the RTV will work unless you clean and dry the surrounding areas very well. Maybe lean the side you're working on up a bit to make sure any standing oil goes back into the center section.
As for the second seal, sounds good as long as you have plenty of room for it. Been awhile since I've been in mine and I don't remember just how much space is available.
Good luck.

Paul

 

[blubuckaroo]

It had been a while since I had been under there and didn't realize I was slinging oil. Slid under the other day to see why it felt out of balance on the hwy. Oil had soaked under the sticky weights and they fell off! I'll oil the road till I have time to fix it.

 

[71 SPORT]

Used rtv on first seal and installed 2nd seal on top of that one.added a tube
Of additive to the gear oil drove around for a couple of hours.
No leak no more binding (so far) don't know what worked , don't really care
Thanks for all the input guys.