Front wheel well covered in smelly oil/fluid

[wagslick]

I stop at a parking lot yesterday and from around my 99 Z71 and notice a potent spell coming from my truck. I look under the truck and notice the drivers side front wheel well is dripping with some sort of oily fluid. I check the master cylinder and pump the brakes a few times and the brake lines are doing fine. I think the issue is a bad seal with the axle.

What should I do to fix this and what parts should I be getting at the auto store?

[j cAT]

Originally Posted by wagslick

I stop at a parking lot yesterday and from around my 99 Z71 and notice a potent spell coming from my truck. I look under the truck and notice the drivers side front wheel well is dripping with some sort of oily fluid. I check the master cylinder and pump the brakes a few times and the brake lines are doing fine. I think the issue is a bad seal with the axle.

What should I do to fix this and what parts should I be getting at the auto store?

this may be the front diff gear box oil vent. If this is not secure or possibly over heating of the front diff may have caused this . check the box fluid level. cold should be 1/2 inch below the hole.

remember do not operate on dry pavement in any 4WD position.


the brake lines also run in this area , this is the other brake line failure area which is common.

the power steering hoses run not to far away so check this also..

[wagslick]

This makes sense as I did throw it in 4WD for a moment or two because of slick pavement from rain the same day. Checked brake and power steering fluid, its all good. Here's my next question: I've been inside a differential a time or two but what is a differential gear box oil vent? Shouldn't the oil be leaking out from the middle of the truck? Why so close to the wheel? It seemed to completely coat the inside of the wheel.

[j cAT]

Originally Posted by wagslick

This makes sense as I did throw it in 4WD for a moment or two because of slick pavement from rain the same day. Checked brake and power steering fluid, its all good. Here's my next question: I've been inside a differential a time or two but what is a differential gear box oil vent? Shouldn't the oil be leaking out from the middle of the truck? Why so close to the wheel? It seemed to completely coat the inside of the wheel.

because the vent hose opening is mounted on the inner plastic fender at the shock top area...dripping on wheel it will throw the oil around

[wagslick]

Originally Posted by j cAT

this may be the front diff gear box oil vent. If this is not secure or possibly over heating of the front diff may have caused this . check the box fluid level. cold should be 1/2 inch below the hole.

remember do not operate on dry pavement in any 4WD position.


the brake lines also run in this area , this is the other brake line failure area which is common.

the power steering hoses run not to far away so check this also..

Originally Posted by j cAT

because the vent hose opening is mounted on the inner plastic fender at the shock top area...dripping on wheel it will throw the oil around

Ahh, you speak truth. After a while of searching I did find the front differential overflow vent. It's mounted on the engine side of the plastic wheel well but spill out right onto the wheel. I traced it from the differential itself. I thought it was an electrical wire at first.

Next question. Is there anyway for me to know if I blew an axleshaft oil seal or just caused my differential to overflow due to 4wd turns in a parking lot. Which seal would I have wrecked, the "output shaft seal", "pinion seal", or "axleshaft oil seal" or are they all the same thing?

[j cAT]

Originally Posted by wagslick

Ahh, you speak truth. After a while of searching I did find the front differential overflow vent. It's mounted on the engine side of the plastic wheel well but spill out right onto the wheel. I traced it from the differential itself. I thought it was an electrical wire at first.

Next question. Is there anyway for me to know if I blew an axleshaft oil seal or just caused my differential to overflow due to 4wd turns in a parking lot. Which seal would I have wrecked, the "output shaft seal", "pinion seal", or "axleshaft oil seal" or are they all the same thing?

like I stated before , if it is from this vent , check the fluid level. it should be 1/2 inch below the fill hole cold.

the oil should be yellow , if black/gray replace oil with 80-90 wt non synthetic as the OEM fluid requirements state , at the level I mentioned.

with the vehicle in 4wd of any position the front axle is locked as one. avoid any sharp turns , this does put great stress on the front diff.

if the diff did overheat this oil will expand and vent out.

[wagslick]

Originally Posted by j cAT

like I stated before , if it is from this vent , check the fluid level. it should be 1/2 inch below the fill hole cold.

the oil should be yellow , if black/gray replace oil with 80-90 wt non synthetic as the OEM fluid requirements state , at the level I mentioned.

with the vehicle in 4wd of any position the front axle is locked as one. avoid any sharp turns , this does put great stress on the front diff.

if the diff did overheat this oil will expand and vent out.

Sweet. You're the best jcat. I think the diff oil venting is what had occurred. Only deal I can't figure out is that I only had the 4wd on for about 4 minutes and then parked in parking lot and I lost 1/4 cup of differential oil all at once (1/4 cup is my best guess judging from the amount of oil in the wheel well and drips on the ground). Not sure how it could or would have overheated by that time. Weird.

Here's my plan (let me know if I'm going about this the wrong way): I'm going to top off the front differential (i can't detect any oil in there with my finger) then degrease the entire wheel well area and clean it up. Then I'll check for leaks after a bit of driving.

[j cAT]

Originally Posted by wagslick

Sweet. You're the best jcat. I think the diff oil venting is what had occurred. Only deal I can't figure out is that I only had the 4wd on for about 4 minutes and then parked in parking lot and I lost 1/4 cup of differential oil all at once (1/4 cup is my best guess judging from the amount of oil in the wheel well and drips on the ground). Not sure how it could or would have overheated by that time. Weird.

Here's my plan (let me know if I'm going about this the wrong way): I'm going to top off the front differential (i can't detect any oil in there with my finger) then degrease the entire wheel well area and clean it up. Then I'll check for leaks after a bit of driving.

if this were my truck the oil will be drained the drain plug cleaned and I would install the correct fluid to the correct level. buy a hand pump to pump in the gear oil from the container ..

check for metal larger than dust size.