The Stovebolt Site Forums The Shop Area Engine Shop Rear axle vented?

While cleaning up my rear axle I found a hole. There is a hole in the top of the axle on the drivers side. Is this a vent?
Should I just leave it alone or should there be a tube attached? Or should it be plugged?
It is threaded.
My truck is a 48 1/2 chevy
TIA

There should be a vent there. It is a pipe nipple with a piece of sheet metal crimped over the end, keeps the dirt and water out. If the hole is plugged, you will blow out the axle seals when the oil gets hot.

I learned that the vent on my 69 uses a piece of rubber tube that is attached to a crossmember and ends near the bed, but it has the same function.

I just lost mine,. The threads in the hole were not in good shape. I found a replacement, retapped the hole with a 1/8 pipe thread tap and threaded in the new one... I added some Locktite as well..

I still have the vent and cap on my (newly) cleaned rear axle. Can I just carefully pry off the sheet metal cap that is crimped on to remove and clean the vent and then crimp the cap back on?

Thanks.

ttt8,

I think that the axle vent hollow bolt also secures the brass brake line junction block to the axle tube....

(Might have this confused with another vehicle, but most cars/trucks vented their axles this way.)

Should be a gizmo that looks like an 1/8" pipe nipple with a thing hex on it for a wrench, more nipple, then a little cap crimped on top, loose enough to vent, but tight enough not to come off.
The vent hose deal came along in the '60s.

The vent on a 48 Chevy stands alone, it is not attached to a brake junction block..

The hose which goes up to the frame helps keep water out if you happen to go through deep water.
We had to install lines from the vent fitting on the axle housing up to the upper part of the firewall on a few fleets of trucks(per company request)
Couldn`t hurt to add a little length Tony M

Can someone please post a picture?
This might help me when looking for an original.
TIA

Soak it overnight in solvent or something that will cut grease and scrub it. Mine was plugged and I was able to clean it without taking it apart.

My vent cap/nipple was rusted solid. Couldn't open it up or find a new one anywhere. Made my own out of a 1/8 threaded by 1/4 barb brass fitting. Then crimped closed one end of a 1/4 brass insert bushing for plastic pipe. Left the other end open and made a slight crimp in the bushing body. Put this over the barb fitting. The brass bushing rises and falls over the barb fitting but the small crimp in the body prevents the bushing from rising over the barb end of the fitting. Works fine.

Couldn't figure out what the heck you guys were talking about until I went "down under". Sure enough on top of my rear axle housing (drivers side) sits this little cap. It's loose yet doesn't want to come off by hand, so I assume it is in working order. What one learns from the bolt.... I can take a pic if people are interested.

cmayna, Would sure appreciate a picture. Mine is missing and I would like to know what I'm looking for. Thanks

Will take a couple shots when I get home. Stay tuned.....

Here it is. Almost looks like it was hand made but it spins freely and won't come off accidentally. Almost looks like something just pulled off the ocean floor next to that Florida bound Cuban AD.

[img]http://www.cmaynard.com/Truck/rearaxlevent.jpg[/img]

Boy, that is an ugly thing.....thanks for the pix..Fred

Cmayna,,,,, If that piece in the front of the pic is your brakeline, I suggest replacing it soon,,,
Man, that thing is rusty

Replace me brakeline???? I just pulled the nipple off the USS Titanic and just knocked off the barnicles...Yes I agree that it needs to be replaced but question before or after my wife drives my truck to her work?