Tapping a rear diff breather

[Catfish28]

Slowly rebuilding my 78 and realized my diff breather is MIA. Assume it's been welded shut and can't really even tell where it was. Question is should I try to tap it back in the same spot or move a few inches? Don't know if the metal is the same thickness throughout or if the particular spot had thicker metal or a "backer nut" or whatever to accommodate the 10mm breather. Maybe it got stripped out and plugged. Thanks in advance.

 

[65swb45]

You should have a threaded hole where your brake line junction attaches to the rear axle. The breather holds the junction down.

 

[cult45]

You should have a threaded hole where your brake line junction attaches to the rear axle. The breather holds the junction down.

I have that, but also another hole in the centre of the longer axle tube. It spits gear oil from time to time.

 

[Catfish28]

That's what I'm referring to. The threaded hole that the breather goes into is welded and the brake junction is flapping in the wind.

 

[65swb45]

Well, this is where I usually pull out my Sarah Palin ("drill, baby drill") but I'd be worried about the metal shavings.

What about draining the diff and rolling the truck upside down first, so the shavings fall away from the axle?

I feel for ya dude. If you don't vent it, you're on a short path to blowing the axle seals. Gotta love POs.

 

[SteveH]

The magnet on the drain plug should pick up the metal filings, and if you grease the drill bit and tap, you can minimize the intrusion. Also, change your diff oil fairly soon after this, and wipe the magnet clean on the drain plug. I would enlarge the PO's hole as a starting point, but if it it's a big mess, then JB Weld it shut (or weld it shut with a welder) and put the vent somewhere else.

 

[shipmag]

I had a friend who looked where the old one was suppose to be and found the vent had broken flesh with the axel carriage. Not sure if you drilled it out or used an easy out and backed the broken piece out. Look real close under the brake line tee and see if you can see under the gunk of road crime if the broken fitting is just covered with road crim and grease.