Front Diff Leak - From Lock Actuator? (1 Viewer)

Joined
Mar 16, 2020
Messages
7
Location
Glendale, AZ
Hello all. I’ve read a number of posts on leaking front diff housings. I’ve got a ‘94 factory triple locked with just shy of 408,000 miles. I’ve confirmed torque is good on all of the bolts.

After parking I get a few drops over several hours from the bottom of the front diff housing which will form a 2” diameter mark on concrete. It will then stop until the vehicle is driven again. This leads me to believe the origin is above the standing level of the fluid. After cleaning and observing, the leak seems to come from the top area of the lock actuator, about 2 o’clock when looking from rear towards front of car. I can’t tell if it’s a bad diff cover gasket right in that area or if it is simply leaking at the actuator interface.

I’m hoping there is a chance it is just the seal between the actuator and housing.....
I‘m currently awaiting the front actuator rebuild kit from Wits’ End. The actuator works ok and I’m debating whether I want to open it up for a rebuild or just pull it and replace the o ring at the interface. I suppose when I get it off I may get more insight into where the leak is originating.

Can a failed seal on the actuator cause leaking diff fluid?? Anyone have success just changing the interface seal?

If that seal is in similar condition to other rubber seals on this rig (oils level sender, distributor o ring, etc) I imagine it could be a simple fix. I want to avoid having to pull the third member until I’m ready to do a complete brif rebuild and there are no indications that is currently in my immediate future.
Thanks
 

fjfodee

At a Medium Pace
SILVER Star
Joined
Dec 20, 2006
Messages
1,434
Location
Lower Left AR.
Could be the 3rd member gasket, or the o-ring on the actuator. The o-ring is the easiest to check first. Do a search on how to remove the actuator. It’s a fairly simple process.
 
Joined
May 26, 2005
Messages
7,919
Location
Phoenix
I had a cracked housing that started as a leak from the locker actuator area. I assumed it was a bad seal between the diff and the housing, as I had pulled the actuator and knew the seal was good there. I could not see the crack on the top easily, and didn't figure it out until the leak got bad. Eventually, over several months, the crack, which started at about 2 o'clock when viewing from the diff side, worked it's way to the diff mounting flange, worked its way down along the edge of that, and then moved away from the flange at about 4 o'clock. It went from a slight drip and spots on the floor to a steady drip that dumped a 3 foot circle of fluid on the floor overnight. I ground out the crack thoroughly and welded it with three passes, adding a bunch of material around the locker cutout at the same time. I had to fill, then re-drill and tap the corner stud holes. Here's some pics, note that this housing was converted from open diff to locked so there are extra stud holes.

Front housing crack cleaned.jpg
front housing crack top cleaned.jpg
Front housing bottom cleaned.jpg
Front housing crack welded.jpg
Front housing welded and machined.jpg
 
Joined
Feb 7, 2015
Messages
691
Location
Eastern Washington
If you pull the actuator assembly off the differential there will be an o-ring on the outside of the stub that goes into the diff. That o-ring is in the rebuild kit you ordered. I just replaced mine and it was pretty hard and rotted. There is also another o-ring on the inside of the actuator but I cannot find a replacement for it and it does not come in the kit. It's some kind of special shape. You'll see it on the shaft just behind the small gear on the end.

You could just replace the seal, should only take about 15 minutes. I just rebuilt my actuators last weekend. Even though they worked well the seals and grease inside needed replacing after 23 years and 290k miles. The front took me about an hour to remove, clean and reinstall.
 
Joined
Mar 16, 2020
Messages
7
Location
Glendale, AZ
Thanks for all the insights. I’m hopeful it is not a crack but appreciate the repair pics. I am generally a “while I’m in there” mentality so I’ll rebuild the front lock actuator while it’s off and do my best to inspect for cracks and or pinpoint the leak on the diff cover gasket. Hopefully the actuator o ring will fix it.
 

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