Rear Brake vent line(?) leaking

[Chehalem_ME]

Hi all, I have a 1995 Bronco XLT and this morning noticed a puddle of fluid under the drivers side rear axle. Crawling under I found what appears to be a vent tube (open-ended tube) slowly dripping oil. The tube comes off of a small module that is fixed to the rear axle and has two metal lines that appear to be going to the rear drums and a pipe that runs up in the frame to the front of the vehicle. The tube that is leaking goes up to the inside frame rail and is just open. I assume it's some kind of vent for the brake system? The brake fluid level up front looks ok. Any ideas on (a) why it's leaking and ( B) how to fix it? I searched the forums but haven't been able to find anything... Many thanks in advance! Mike.

 

[Roadkill]

That hose is a vent for the rear axle. It is routed through the same metal block that the brake line runs through. (not sure why its designed that way) It should be gear oil from your axle, not brake fluid coming out of the hose. If you've got fluid coming out of it you may want to check the condition of the oil in the differential.

 

[Chehalem_ME]

Thanks for the reply Roadkill - I'll check the diff this morning. Any ideas on why it would just start pushing oil out the vent tube? The Bronco hadn't been driven for 3 or 4 days and was just parked when it started dripping oil.

 

[Roadkill]

I cant really think of why any significant amount of oil would come out there. The vent is to relieve pressure inside the axle as the oil heats up when driving. If there were no way to vent (or if it were clogged up) the pressure would seek the weekest spot to relieve itself. Most likely by blowing through the axle seals into your brake drums. The hose is there to make the opening higher off the ground so that water does not get into the axle when driving through water. A drop or two would probably just be vapors condensing but your description sounds like you have more than that. Is it parked on level ground or is it parked with the passenger side significantly higher than the drivers side?

 

[Chehalem_ME]

Parked on dead-level ground. It was driven about 12 hours previous to when I noticed the oil dripping. The truck hasn't been worked on in a few months (and that was just an oil/filter change). Temperature was only about 75 degrees (nice and cool up here in the NW /emoticons/[email protected] 2x" width="20" height="20" /> ). There was at least a drip every 30 seconds or so. It stopped after I drove the truck about 1/4 mile but I haven't checked this morning yet...

Since the tube is higher than the axle then I'm guessing there had to be some kind of pressure build-up in the differential. Not sure what would cause that all of a sudden (especially with the mild temperature and just parked). I'll check the oil this morning and see what Ford says on Monday -- I'll post what I find.

Thanks for the replies - Mike.

 

[miesk5]

yo;

clean it out, change the fluid; normal maint sched calls ffor 8.8 Differential drain & fill (80W/90 for non limited slip version) @ 100k miles.

also, found this, for an Explorer tho,

"Front axle leak. Some 1995-2001 Explorers and 1997-2001 Mountaineers and Ranger pickups may leak fluid from the area of the front axle vent tube. According to Ford, the most likely scenario here is that the **** in the diff is being thrown toward the axle vent upon rotation of the gears during normal vehicle operation.

A new-design front housing cover with a built-in splash baffle should eliminate the problem. You'll find the new cover packaged in a special kit (Part No. F6TZ-4033-BA), which also includes a new vent hose, plug, connector and clip, as well as a tube of sealant and installation instructions. Since most of the nuts and bolts in the front differential are of a torque prevailing design, and thus can't be reused, you'll also need to order up a new axle bolt and washer (Part No. N80B403-S426), pinion bolt and washer (Part No. N811242-S426), nut and retainer (Part No. 811623-S426) and wheel end nut and washer (Part No. N808985-S100) to complete the repair. In case you're interested, Ford allows 1.7 hours to swap in the new parts."

heard of this happening to other Broncos; just have it serviced for now.

and on later year Super Duties