Slick 60's

What would cause fluid to leak in small amounts from the vent tube on a 9" Ford rear? The leaking has been occuring for some time and happens while the vehicle is driven, not when it is sitting overnight. I checked the oil level, and it seems ok (not overfilled).

How long is your vent tube? Originally, they clipped onto the frame near the bottom side of the bed, with a little extra slack beyond that. If your tube is shorter than about 30", that could be your problem.

We usually ran vent tube hoses to a place on the frame where it could be tied off. You need slack in the hose to compensate for the rear axle movement.

It leaks uphill 12-18" into the frame rail?

You must have some enormous pressure build up in there... better check for it being plugged

The vent is directly on the axle, very short, and has a cap on it that slides up and down. It is much like you would see on a front axle on a 4x4 slick. I can move the cap up and down easily. When I got the truck, the vent cap and the area surrounding it was caked with rear end oil and dirt. It must have been leaking for some time. I thought a clogged vent may have caused the leak. I cleaned it up, but I still get a little drip after I drive it 10 or more miles and park.

The truck may have pulled heavy loads by the PO, I do not know it's history. Is it even something to worry about?

Do note, the truck is a 76 f150 4x4. I was hoping a 9" rear is fairly universal through the years. Please don't yell at me for posting on this forum. I have always gotten acurate advise here. Yes I did try the other place! :wink:

I'm thinkin' a PO has probably done away with the original vent tube for whatever reason...even though it's a '76, it still should have had one originally. My '78 Bronco did, with it's 9" rear end.

Here Mud Dobbers move in and block the tube causing it to leak fluid otherplaces when it is hot.

FBp

We used to remove the factory vent pipe. We then installed a fitting like a fuel fitting for 3/8" fuel line. The race cars got two vents, in the axle tubes on each side of the chunk. As I said before, the hoses went to a convenient place on the frame to be tied off.

ok, so it leaks when it get hot. I do not think it would get hot enough during normal driving. I am just drivin around town, like an old lady i might add due to the gas prices. The temp should be in spec..unless something is wrong? maybe the oil is old and needs changing or something like a bearing going bad?

should i just blow it off and makeup a mod vent tube as suggested?

BTW the vent is stock according to the pic in the Chiltons manual.

did you check the fluid level? everytime I have had a leak from a customers vehicle it was usually because it was overfilled, shouldnt be up to the fill plug but about half inch below it

that explains the leak. I took the filler plug out and some oil leaked out. The level was up to the plug, not half an half an inch below. I thought that was where it should be. The repair manual I have is not specific on the level. I will drain some out and see how it goes.

Thanks for the tip!

use allen wrench to measure

Also, check the pinion seal. Its an easy fix with some silicone but it usually is the one to leak.
I second the idea of a fuel fitting and a rubber fuel line run up to the top of the frame.
U@ss

I'm guessing it's an older axle that the PO swapped in. Sounds just like the one in my 63. A hose and filter would be a good idea, to keep it cleaner in there, but I've had no trouble with it. Surprised it has never dribbled from there... Keep the juice down a little and you should be sweet.

blackagatha wrote:I'm guessing it's an older axle that the PO swapped in. Sounds just like the one in my 63. A hose and filter would be a good idea, to keep it cleaner in there, but I've had no trouble with it. Surprised it has never dribbled from there... Keep the juice down a little and you should be sweet.

my 63 also has the capped breather, both front and rear axles, so its probably an older unit....