I hopped a curb the other day, and then noticed this tube dangling from my truck. For the life of me I can't figure out where it was supposed to connect. It doesn't seem to do anything, nothing has come out of it, and everything still works. Anybody know what this is or where it goes?

 

It's athe vent for the rear end. Look higher up on the frame and you will see a clip the holds it up.

 

I was hoping it was something like that, so attaching it any old place should be fine then I'm guessing. Thanks a bunch.

 

If you look right up above it on the frame, there should be a clip that it attaches to. However, make sure the hose is long enough so after its clipped into that bracket,,, the open end hangs down so no water is splashed into it. ALSO, take into account for the length of travel that will be needed when the truck frame is lifted away from the housing.
If it were me, I'd get new hose. Those hoses can get old and brittle.

 

Also make sure the tube is clear of any obstruction (mud, bugs etc.) soas to allow the air to escape when the axle heats up. If this vent is blocked it could lead to a leaking seal and oil in your brake drum!
Ulfie

 

AU yes, why I suggested a new one.

 

What year is your truck?
Where did the rear end housing come out of?
I don't recall a '66 F100 rear housing having a fill plug in the rear like that one has........ ??

BarnieTrk

 

It's a '66. Standard 9" rear end as far as I can tell. Though a quick google search tells me you're right, that's a non standard drain location. It would not surprise me if this was a DIY repair from the previous owner, the more I drive this truck the more of these "fun" surprises I keep finding. Looks like I'm ripping apart my rear end this weekend to make sure there's nothing else to see here.

 

IT IS NOT A DRAIN. It is a vent tube to allow pressure variants.
If you have never worked on final drive systems before, I might suggest seeking out someone's help before just jumping into it or you might do something you really don’t want to do. I've set up a few pumpkins in my life, and that is an education on its own. Gears are not cheap to replace but they are easy to screw up if they are not set up correctly.

But than again, I'm just a crazy old fart and most likely have no idea what I'm talking about.

 

I think the "drain" in question is the leaky plug on rear of the differential housing. I think that's a Ford 9 inch but I didn't now they had fill plugs there...might be a home made deal.

Anyway, while the OP is replacing the vent hose, I like to remove the fitting and clean it. Good time to replace that faded brake hose too.

 

That is a 'FILL' plug. With the truck setting on 'level' ground, you fill the housing to just below the bottom plug hole thread line. Remember, if you have a LS pumpkin, you need to use FMC additive.

 

There isn't much meat on the rear where that plug is located....so if it was a home-made deal, it likely only has 1.5 threads worth of material to hold the plug. if that is the case, it's probably the reason why it's leaking. I seem to recall some 9" housings had them, I just don't think they were OEM in a '61-'66 Slicks. I recall being warned if swapping carriers to get a different ratio, be aware that some rear ends had the fill plugs located in the front carrier and some had the fill plug on the rear of the housing. It wouldn't be hard to install a carrier without a fill plug into a housing that didn't have a fill plug in the rear, then you'd not have a way to add gear lube!

BarnieTrk

 

 

 

Easy to check. Take the plug out and see if there is a threaded ring insert welded in. I've seen housings with a fill plug in the back and they were flush. BUT, pull the plug and see. Now I'm curious.
Is there a fill plug on the drive shaft side?
If ya don't tell us, I will never be able to sleep. :-)