After about 1.5 hrs of reading threads about the front axle, I really haven't discovered anything but the fact that the vent tube on my 97 4x4 should be on the end of the axle tube. There is a good amount of gear oil coming out of the front axle vent tube. I have changed the gear oil and only achieved getting clean fluid out the vent tube.

Quick list of things (some maybe unrelated) leading up to vent tube leak:
- Got truck stuck in soft ground and I could not get 4wd to engage (after reading, this is probably a vacuum problem)
- Soon after, I started noticing fluid in passenger fender well, thought it might have been a ripped axle boot. After inspecting the the boots, I found it was the axle vent. At that point I started driving it on a limited basis.
- One day while using the truck to setup for a local SCCA event, I was in the bed while the truck was being driven and noticed gear on gear noise coming from up front (not whine, but more of old gears with little lube) I changed the fluid and found the drain plug was "caked" with material, but as old as the fluid looked, I figured it may have been the original fluid (with 150k on it!). As mentioned above, it's still leaking out the vent. Even to the point that is leaves spots all down the side of the passenger side after driving down the interstate.

My guess is that the R&P are toast now (by the gear on gear noise). Is there a write up on removing the front differential assembly? Where is a good place to get new, quality R&P and bearings? I will probably have a local off road shop or mechanic actually do the differential work. Is it worth just finding the axle assembly from another 4x4 and replacing it?

Thanks,

Andrew

 

andy, i have the same issue, i even revised the breather tube to the later years location and it still pukes. its speed and temp related. mine blows at 75+ mph and on trips over 2 hrs on the interstate.

if you want to just yank the front pig and replace it with a lower mileage with same ratio you could probably pull it off in a days time... but til i find a fix that actually works, it seems to be a casting issue with the 97's.

is your build date 6/96 or earlier?

 

I'll have to check on the build date. I was just surprised when this problem started recently. I've had the truck for 4 years and put almost 50K on it (much of it towing to and from SCCA races and daily interstate trips to work) with no signs of this problem until I finally tried to use the 4wd system.

 

yep same thing here. i got stuck in a river bed (silt) and the problem popped up then, or became noticeable.

 

My 97 (98000 miles right now) started leaking late this summer. The fluid was changed in late June. Doubled checked with the mechanic recently and he said there was probably too much fluid added when the change was done but that it wouldn't hurt to drive the truck. I plan to have it checked at the next oil change just to make sure the fluid is not too low now.
I don't know what started this. The truck is now being driven more since my son turned 16 last fall/winter but he is a careful driver and I know he has used the 4wd a couple of times when needed (as have I). The only other difference is that the truck no is longer parked in a level garage but on the street with the right front lower than the rest of the truck. I don't hear any noise from the front end.

 

sounds like all the front diff fluid is making its way on to the side with the vent tube, and not draining back to the front diff.
I kind of had the same problem, except for it was in my rear diff.
The problem was a casting issue. Where the carrier bearings sit in the housing, there appeared to be a small drain hole(a small groove), to allow gear oil to flow back into the center section from the axle tubes. One of those drains had a bit of excess cast onto it, therefore not allowing fluid to drain back into the center section. I also noticed that this side had a leaky axle seal, probally from all the fluid getting stuck in there and not finding its way back to the center section.
SO, I measured out how the opposite side looked and was machined out to allow the gear oil to drain from the axle tube, and i went at the other side with a cutoff wheel on my dremel and a small file. I mirrored the drain on the other side, and Voila! that side of the axle tube now has a drain to allow gear oil to flow back into the center section.
The front center diff on my 02 is pretty easy to unbolt. 3bolts hold it in, 15mm?and the cv joints have 6 bolts on each flange 12mm 12point. Driveshaft flange have 4 bolts which are the same size as the cv joint flange bolts. once you get the truck jacked up on stands, it took me about 30 minutes to drop the front diff.
Hope this is some helpfull info.

 

Interesting how something like this can take a while and certain conditions to show up. I'll have it checked at the next oil change (I'm not that mechanically inclined to try something like this). Thanks for the info.