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Gear oil in LF wheel well?

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Old November 14th, 2022, 3:40 PM
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Default Gear oil in LF wheel well?

Hey All,
I recently bought a 2003 2500HD. Walked out this morning and saw a splash of oil in the drivers wheel well. Huh..?? Has a gear oil smell to it. Lower control arm, cv boot, sway bar, etc. all wet. Got under the truck and for the life of me couldn't figure out where it is coming from.

Finally I found what I believe is the breather tube attached to the engine compartment side of the driver's wheel well. The little plastic vent in the end was wet with oil. It looks like it vented oil which dripped down to the bottom of the wheel well and then got blown back across the lca, cv boot etc.

Anyone ever heard of this? If so, a cause?

I'm at a loss. Thanks for any ideas/info.

CE
Old November 14th, 2022, 6:28 PM
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That should be the vent tube for the front differential.

The vent valve in the diff is known to stick and allow gear oil to build up and get pushed out the vent.

The fix is to remove and clean the valve. Use a 7/8” socket to unscrew the vent and clean it until the metal baffle on the inside spins freely. Brake cleaner and compressed air are the most efficient way to clean it.

Replace the O-ring if the old one is damaged or deformed. Apply oil or grease to the o-ring and screw the valve back in until it’s just snug.

While the vent hose is detached, give it a quick shot of compressed air to help clear dirt build up inside it. If it’s clogged bad enough and/or deteriorating, I recommend replacing it with emissions grade tubing (bulk/off the shelf is fine). The vent cap can be transferred to the new hose.

I’d also recommend checking both axle seals for leaks. What oftentimes happens is the restricted vent allows enough pressure to build and take out the axle seals.

Note that if the right (passenger) axle seal needs replacement, it requires removing the R side axle housing as an assembly.

All parts are typically available at any average parts store or dealership.
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cdevrard (November 16th, 2022)
Old November 16th, 2022, 6:49 AM
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Originally Posted by Gumby22
That should be the vent tube for the front differential.

The vent valve in the diff is known to stick and allow gear oil to build up and get pushed out the vent.

The fix is to remove and clean the valve. Use a 7/8” socket to unscrew the vent and clean it until the metal baffle on the inside spins freely. Brake cleaner and compressed air are the most efficient way to clean it.

Replace the O-ring if the old one is damaged or deformed. Apply oil or grease to the o-ring and screw the valve back in until it’s just snug.

While the vent hose is detached, give it a quick shot of compressed air to help clear dirt build up inside it. If it’s clogged bad enough and/or deteriorating, I recommend replacing it with emissions grade tubing (bulk/off the shelf is fine). The vent cap can be transferred to the new hose.

I’d also recommend checking both axle seals for leaks. What oftentimes happens is the restricted vent allows enough pressure to build and take out the axle seals.

Note that if the right (passenger) axle seal needs replacement, it requires removing the R side axle housing as an assembly.

All parts are typically available at any average parts store or dealership.
Thank you ! Gonna try this. Best CE
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