Leaking Front Axle Seal (With Pictures)

[wagslick]

I have a 1999 Chevy Silverado Z71 with 5.3 L Engine. I noticed a small puddle of very light oil under my truck yesterday in the driveway. After crawling under the truck I think I identified the location of my leak. It seems to be coming from a seal on the passenger side of the axle not far from the accordion looking thing. What is the name of that seal and how should I go about fixing it?

I don't know the name of every part (as you can tell) but i've replaced fuel pumps, rotors and pads, and window regulators. I'm kind of handy but I'm not sure if this project is over my head. Here is a picture of my leak

[j cAT]

Originally Posted by wagslick

I have a 1999 Chevy Silverado Z71 with 5.3 L Engine. I noticed a small puddle of very light oil under my truck yesterday in the driveway. After crawling under the truck I think I identified the location of my leak. It seems to be coming from a seal on the passenger side of the axle not far from the accordion looking thing. What is the name of that seal and how should I go about fixing it?

I don't know the name of every part (as you can tell) but i've replaced fuel pumps, rotors and pads, and window regulators. I'm kind of handy but I'm not sure if this project is over my head. Here is a picture of my leak

this looks like the front gear box axle seal.

the gear oil to use is 80-90wt GL5 ..did you replace this oil lately or did someone else ? this gear oil is a heavy oil...could be engine oil spilled down from fill spout ..check the gear box oil level should be 1/2 inch below the fill hole when cold...when hot at the top of fill hole.....

some times these will weep when temps change then stop leaking...

[wagslick]

Originally Posted by j cAT

this looks like the front gear box axle seal.

the gear oil to use is 80-90wt GL5 ..did you replace this oil lately or did someone else ? this gear oil is a heavy oil...could be engine oil spilled down from fill spout ..check the gear box oil level should be 1/2 inch below the fill hole when cold...when hot at the top of fill hole.....

some times these will weep when temps change then stop leaking...

Sorry, I didn't mention that this pic is from the passenger side of the truck, the opposite side of the front differential (is that what you meant by "gear box"?).

I did however recently (2 months ago) top off my differential oil. I think I had a plug in my differential overflow valve because a bunch of stinky differential fluid gushed out onto my drivers side wheel well. I topped off the fluid and all was well.

Here's what I'm wondering: If in fact the differential overflow valve is clogged that would break one of the CV joint-to-axle seals/gasket.

[j cAT]

Originally Posted by wagslick

Sorry, I didn't mention that this pic is from the passenger side of the truck, the opposite side of the front differential (is that what you meant by "gear box"?).

I did however recently (2 months ago) top off my differential oil. I think I had a plug in my differential overflow valve because a bunch of stinky differential fluid gushed out onto my drivers side wheel well. I topped off the fluid and all was well.

Here's what I'm wondering: If in fact the differential overflow valve is clogged that would break one of the CV joint-to-axle seals/gasket.

the seals are the gear box seals...these are where the axles enter the gear box..

the gear box vent is mounted on the driverside inner fender. this must be cleaned and tested for no restrictions..this plugs into the gear box..with the fill plug removed using a small hand air pump make sure its clear and open..


with the oil cold fill to the bottom of the fill hole..on level ground....

what oil did you install 2 months ago ? if not 80-90 gl5 drain this all out and refill with the correct oil...


IF the box can not vent , the oil will leak out at the seals..with the age of this vehicle most likely this did no damage ...

slight leaking here is common...if the leak is minor just a drop from time to time...monitor the level at the oil change time and check condition of oil should be yellow , not gray yellow...

[wagslick]

Originally Posted by j cAT

the seals are the gear box seals...these are where the axles enter the gear box..

the gear box vent is mounted on the driverside inner fender. this must be cleaned and tested for no restrictions..this plugs into the gear box..with the fill plug removed using a small hand air pump make sure its clear and open..


with the oil cold fill to the bottom of the fill hole..on level ground....

what oil did you install 2 months ago ? if not 80-90 gl5 drain this all out and refill with the correct oil...


IF the box can not vent , the oil will leak out at the seals..with the age of this vehicle most likely this did no damage ...

slight leaking here is common...if the leak is minor just a drop from time to time...monitor the level at the oil change time and check condition of oil should be yellow , not gray yellow...

Thanks for the tips. Actually I think around 1/4 cup of this fluid has spilled out onto the driveway while it was parked.

[j cAT]

Originally Posted by wagslick

Thanks for the tips. Actually I think around 1/4 cup of this fluid has spilled out onto the driveway while it was parked.

measure the amount to fill to the bottom of the fill hole when cold... then you will know for sure how bad..most containers have ounce marks on the side of the containers. using a bottle hand pump /,,,pump to the point where the oil flows out..

If you are loosing a few ounces over 3-4,000mi I would consider replacing BOTH seals , not just the one...

this may be the vent is restricted causing all this..as this oil does expand quite a bit when it gets hot....gets real hot when working in any 4wd position and if you have tires of different wear on the front will damage the gear box.........the front tires must be matched ...tire rotation is very important with these vehicles then 4X4 issues are reduced..

[jdmccright]

Changing the differential oil seal will require removal of the passenger side CV joint/half shaft. This means disconnecting the wheel knuckle/bearing hub from the ball joints, which means having to remove tension in the front torsion bar. You'll need some good jacks, stands, and a big ass cheater bar to remove the hub axle nut, ball joint separator (I don't like the pickle fork kind), and a torque wrench capable of at least 220 ft-lbs to get that nut back on tight.

It is not a light undertaking, but it can be done in a long afternoon for a first timer, but plan on going to the parts store a time or two to get the right size socket for the hub nut, other tools, etc.

I got a 4-ft length of iron pipe from the hardware store to use as a cheater bar over my 1-ft 1/2" breaker bar. I also bought a shorter, larger inner diameter piece and an adapter to screw together to fit over my torque wrench's handle...absolutely recommended as a time and back saver.

I also like the jaw-type pitman arm puller to dislodge ball joints rather than pickle forks which can tear the grease boots of joints you want to reuse.

Good luck!

[kahjdh]

I found that if you disconnect the upper bj there is enough room to tilt out the knuckle to get the axle out. These seals are not too bad to replace. The last one I did at work was abot 45min but that was with a lift and box full of tools. Driveway though might be alittle tricky-er but shouldn't take more than an afternoon.

[weo38]

You don't have to take the cv shaft out. There is enough room if you move it to the side. On the passenger side like in the picture you take that whole assembly off. By that I mean the tube where it bolts to the diff case. Then you can work on getting the drive shaft out on the bench. Grab a Haynes manual, very helpful for this type of job. Well worth the 20 bucks or so imo.

[wagslick]

I tell ya, this is why i love automotiveforums. Thanks for all the tips guys. It's rainy today but i'll probably tackle this problem pretty soon. Thanks again!

[jdmccright]

I think weo is right...can't believe I didn't register the bolted flange in the photo; I saw it but I didn't SEE it. Anyhow, you should be able to unbolt the half shaft support bearing bracket (shown) and undo the flange bolts to move it out of the way. You might turn the wheels one way or the other to reduce the bending angle at the outer boot joint. Just don't let it flop down loose...support it with a jackstand or use wire to tie it up against something else.

Good luck!