opdsgt

Earlier this year, I experienced enough articulation to pull the front diff vent off. So I extended the vent w/a longer piece of tubing. I left a good deal of slack (think of a big, droopy "J" coming off the diff) and added a hose clamp too. Figured I was good to go.

Enter Chinaman Gulch last week. If you don't take bypasses, it's gnarly. We spent nearly the whole day climbing up and down the trail's considerable boulders and waterfalls.

Turns out, spending so much time with my nose in the air (trying multiple lines, mugging for the camera, etc.) allowed gear oil to fill the "J" in my vent and spill out. Ounce by ounce it went.

The next day (with diminished oil level) I got on the slab and ran 75-80 mph back to Omaha. The end of my vent sits out in the open behind the radiator, a high airflow area. Fast moving air running across the top of the breather may have created negative air pressure, further draining my front diff during the ten hour journey back to Nebraska.

Once home and slowed down, I immediately detected the nauseating sound of pinion bearing failure and found my vent line shiny and dripping with gear oil. My gear man confirmed my fears. I've got a master overhaul kit coming from Northridge.

Lessons learned:

1. If you find the need to extend your front axle vent for off-road purposes, be careful not to allow too much slack in the tube; have the excess in a vertical rather than horizontal plane.
2. Likewise, make sure the end (breather) isn't in a high airflow location.

PITA! But alas, this sort of thing kinda comes with the territory.

UPDATE: photos of failed bearing - see Post No. 14

kd5zwf

Man that sucks! Were they the stock pinions?

opdsgt

Yukon 4.88s from David.

Looks like my gear set is fine.

bigbluejk

Man that sucks!!! Thanks for the heads up. That could have been much worse tha just a bearing, glad it wasnt. I love the jeep!

Sorry for the hijack but are those mtr's 35x12.50R17? If so what load range are they? How they ride on the pavement? they look insane under there.

opdsgt

Indeed, 35x12.50 MTRs, C-range, much better pavement ride @ street pressures than my old KM2s (D-range, stiffer sidewalls).

Glad too it was only the pinion bearing. Drive long enough like that and you can compromise the gear set. Spooky.

bigbluejk

no doubt... I read that whole post the whole time thinking your gears were toast till you said it was just the bearing. it doesn't take long at 75-80mph.

Thanks for the info about the tires. great jeep!

sm_rubi

I extended mine into the engine bay in a horizontal position, but, haven't had issues. I'll have to take a look and make sure the levels are good. Thanks for the heads up!

jeepmedic

Did you get the whine noise from the front during acceleration ?

opdsgt

No. Like I said, the gear set is unharmed.

bigbluejk

hey I am no mechanic or anything but I have had a couple regears over the years and had friends with some etc... anyway are you having a noise during acceleration? Is is during the take of or mostly when you let off the throttle. if it is off throttle is may be a crush sleeve issue. If it is under throttle over like 15-20mph I would wonder about the bearings and if you reused the old or replaced them during the setup. Could be the gear alignment is off too.

Sorry for the hijack, just wanted to make sure no one has noisy gears. It is bad news and needs to go back to the installer for checking.

Leaking out oil like that likely wouldnt have made much noise until it was too late. Good think it wasnt a long trip home!