Oil leak on the diff
Thread Starter
Burning Brakes
Joined: May 1999
Posts: 1,132
Likes: 1
From: Bradford,Mass.,USA
Oil leak on the diff
The pinion oil seal, where the drive shaft enters the diff, is leaking on the 70. Can I fix it with the differential in place, by just removing the drive shaft and putting in a new seal, or do I need to drop the differential?
Thanks, Chris
Thanks, Chris
Tech Contributor
Joined: Aug 1999
Posts: 15,175
Likes: 3,986
From: Connecticut, USA
Re: Oil leak on the diff (Mag Red Man)
This can be done on the car but you must mark the position of the pinion nut to the pinion end so that you put in back in the same position. That way you should lose the preload on the bearings. The drive shaft should be removed so mark the position relative to the tranny yoke.
When installing the new seal put #2 permatex around the seal OD and the the yoke splines to preven the oil from seaping out. the seal is not meant to be driven in flush with the housing, the depth of the counterbore is shorter then the seal thickness. GM made a gage for the dealers to install the seal, it's nothing more then a 1/8" piece of sheet metal the has a radius to fit around the seal. You can use a piece of 1/8" metal and tap the seal in uniformly until the 1/8 metal fit evenly and snugly around it. Don't forget to put some grease on the seal before sliding the yoke in. You may need an impact wrench to break the nut or a pipe wrench top hold the yoke and a 1/2" breaker bar. Buy the GM seal it looks like a better made one then some of the aftermarket ones I've seen.
Good luck,
Gary
When installing the new seal put #2 permatex around the seal OD and the the yoke splines to preven the oil from seaping out. the seal is not meant to be driven in flush with the housing, the depth of the counterbore is shorter then the seal thickness. GM made a gage for the dealers to install the seal, it's nothing more then a 1/8" piece of sheet metal the has a radius to fit around the seal. You can use a piece of 1/8" metal and tap the seal in uniformly until the 1/8 metal fit evenly and snugly around it. Don't forget to put some grease on the seal before sliding the yoke in. You may need an impact wrench to break the nut or a pipe wrench top hold the yoke and a 1/2" breaker bar. Buy the GM seal it looks like a better made one then some of the aftermarket ones I've seen.
Good luck,
Gary
Melting Slicks
Joined: May 1999
Posts: 2,897
Likes: 0
From: Moon Township PA
Re: Oil leak on the diff (Mag Red Man)
Beacuse of the load and the "crush" that is put on the pinion collar, some folks say that this is not for the average guy. My pinion seal was leaking and I just checked the level a couple of times a year. Call me lazy or call me scared, but I chose to live with the slight leak.
Others over at the NCRS discussion board at: http://216.122.167.32/forum/tech.cgi are having a discussion about this right now. Look for the thread labeled "Oil leak on the 70 differential". They discuss it in better detail than I can
Gary
Others over at the NCRS discussion board at: http://216.122.167.32/forum/tech.cgi are having a discussion about this right now. Look for the thread labeled "Oil leak on the 70 differential". They discuss it in better detail than I can
Gary
