The Stovebolt Site Forums The Shop Area General Truck Talk Breather tube on rear axle housing

I have a ’53 3600 with the original rear end. On the top of the rear axle housing on the driver side, there is a small tube with a loose fitting top that I take to be a breather tube and cap (the cap appears to be simply crimped on to the tube but spins). Recently the rear end seemed to be leaking (never before) so I changed the gear oil in the rear end up to the fill plug on the back of the housing. After some driving, I see that it is dripping a little gear oil again. I wiped the casing with dry paper towels and have determined that it is coming from the “breather cap”. Should this breather have some felt or other suitable packing inside to allow for air to escape and enter but prevent the oil from “blowing out”? There appears to be nothing under the cap as it turns freely and is loose. There is nothing that I can find in the shop manual that mentions this.
John

I have pulled a few of these and never seen any packing in them. If it continues there are several improved "street rod" applications that have check valves to prevent the spilling of fluid.

You are right it is a breather. If the cap is loose the breather is generally not stopped up & the fact that oil comes out is another factor that it is not pluged up. Oil should not come out of it though. You may be getting it too full or it is not the proper grease & is foaming. Sometimes the cover gets put on upside down causing the fill level hole to be up way too high. The level of the grease should be about even with the lower part of the axle tubes.

Even new Gm trucks specify to fill the rear axle about full to the hole or about 3/4" low.