I noticed an oil leak after the truck had been sitting for 2 weeks. Looks like it is coming out the vent of the front differential. Some of the stuff on the web makes it just sound like "gear splash" pushes it out the vent.
I did drive with the hubs locked for about 500 miles this winter, not in 4x4. Just getting too old and lazy to lock and unlock them for short burst of 4x4 use.

Never have changed or added oil to the front. Not sure if I have ever pulled the plug to check the oil level.

So here is a photo... Can this be fixed?
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Well I recommend doing that now! Should there be a hose on that vent nipple?

If it was me, I would change the oil in it by sucking out the old. Then I would clean the vent nipple and all around it, and put a hose on the nipple. Then I would just keep an eye out for further leaking.

 

My only experience with differential vents is that the one on my 1986 2WD became blocked [dirt dobber?] and the pinion seal began to leak. Once the hose was replaced, the problem went away, thank goodness. However, the hose was much longer and was factory routed higher than the axle, so perhaps it allows for some expansion/vapors without loosing the lubricant?

 

A pic of Rusty's front diff is coming, as soon as I finish my second cup and discontinue my languishing in the sunlight coming through the back porch windows on this cold morn.

 

First thing I would do is take my finger and run it through that muck and then smell it. If it's not super stinky then it's not gear oil. It may be from a leak on the engine above, or it may just be leftovers from oil changes. The oil filter is right above that area on the v8's. And the oil pressure sending unit is also.

 

There IS supposed to be a vent hose. But, Rusty only has a stub, as shown below.

 

And if you're lucky, there's a stub of a hose still attached to the frame with the clip. Kind of doubt it though, as when the hose breaks by the nipple, the rest usually takes the clip with it down the road.

 

The oil on the outside does smell like stinky gear oil and does not seem to be coming from above, last oil change was done 4 months ago.

I did pull the the fill plug and did the finger check, oil was very clean and looked like new oil. I am sure the gear oil is 30 years old. The gear oil smell is less than I remember last time I filled the rear differential. The rear end has a intermittent pinion seal leak.
The front differential oil level was about .25 inch lower than the plug but the truck was on a slight up-slope, the front wheels are about 3 inches higher than the back wheels.

I did find the clamp where the vent hose was supposed to attach, it is on the frame just behind the top of the differential, see photo below.

Was the original vent hose smaller like vacuum line or more like 1/4" fuel line? Any thoughts on what to put in the end of the vent hose to act as an air filter?

Jim
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The vent hose is larger, not vacuum line. As for the end, I like to use a cheap fuel filter. That way no critters nor mud-dobbers get in.

 

JimsRebel, You still have part of the old hose with a clamp on the rear end nipple. Once the hose is off you will see what size hose will fit the nipple. 5/16 or 3/8 fuel hose and if you want to get fancy add a fuel filter to the end.


The hose is long and up high so when you go thru deep water & mud the rear end does not fill up with it.
You should have a vent w/hose on the rear axle also and the hose would be up high maybe tucked into a bed cross member?
Dave ----

 

JimsRebel - Good to see that clip is still there. And yep, larger hose, like fuel hose. Remember to keep a bunch of extra slack in it too.

FuzzFace2 - For the rear, there's a metal clip that holds the hose and clips onto the frame rail. Kinda looks like a "S" clip.