Leaking Rear Question

nuwave · Post by **nuwave** » May 25, 2007, 10:21 am

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).

Slick Fan · Post by **Slick Fan** » May 25, 2007, 10:35 am

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.

jakdad · Post by **jakdad** » May 25, 2007, 11:36 am

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.

Johnny Canuck · Post by **Johnny Canuck** » May 25, 2007, 11:44 am

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

nuwave · Post by **nuwave** » May 25, 2007, 12:36 pm

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:

Slick Fan · Post by **Slick Fan** » May 25, 2007, 1:37 pm

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.

FORDBOYpete · Post by **FORDBOYpete** » May 25, 2007, 2:32 pm

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

FBp

jakdad · Post by **jakdad** » May 25, 2007, 4:21 pm

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.

nuwave · Post by **nuwave** » May 25, 2007, 5:29 pm

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.

shawns fords · Post by **shawns fords** » May 25, 2007, 5:58 pm

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

nuwave · Post by **nuwave** » May 25, 2007, 6:11 pm

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!

shawns fords · Post by **shawns fords** » May 25, 2007, 6:12 pm

use allen wrench to measure

Uncle Skip · Post by **Uncle Skip** » May 25, 2007, 6:20 pm

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

blackagatha · Post by **blackagatha** » May 29, 2007, 11:45 am

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.

NJ2000R · Post by **NJ2000R** » May 29, 2007, 12:00 pm

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....