Diff. Leaking

curt 5.7 · 04-07-2009, 05:00 PM

On my 93 gmc the rear diff. is leaking oil from the seal by where the drive shaft bolts to the diff. (forgot what the seal is called), anyway I changed it and it's still leaking but about half of what is was is there any additive I can put in the diff to stop it?Or should I change the seal and coat the edge with silicone or something.The diff was a posi. but I changed it to a limited slip (all I could get).

truckabuser · 04-07-2009, 06:29 PM

depends how bad it leaks i guess. if you gotta chase it down with a quart every 100 miles, i'd consider getting something done with it. that's my opinion.

oh, called a pinion seal...you know, ring and pinion....ring gear pinion gear...

curt 5.7 · 04-07-2009, 06:38 PM

I cleaned the vent tude and it seemed fine.Before I changed it, it used about a quart for 1000 miles.Now it will drip about a teaspoon for about 30 miles.But it should not be leaking if I changed it.Did a nice under coating to the box though, the oil is hard to get off.

leolkfrm · 04-07-2009, 07:17 PM

see if another brand seal runs on the shaft on a little different place, a hardened old seal will cut a light groove, and even a new seal at the same point will leak

curt 5.7 · 04-08-2009, 07:17 PM

I will check too see if there is a grove in the shaft, I was sure I seen one.If not I will get a new seal silcone it in and see what happens.

bradrhale · 04-08-2009, 07:53 PM

silicon on that seal is not going to do any good. the shaft has to turn in the seal. the silicon will rub off very quickly. if there is indeed a wear spot on the pinion, some seal manufacturers sell a wear ring that get shoved on there. other solution is to purchase a new pinion. again, if this is indeed the problem.

hotrodpc · 04-08-2009, 11:01 PM

Brad beat me to it. The silicone isn't gonna fix it. I think Leo has the best suggestion. Try a differant brand seal that may ride on the pinion yoke in a differant spot, either before the groove or after doesn't matter. It is also possible your pinion bearing is wore out, and wobbling around alot and chewing up your seal, or wobbling around enough to let there be a gap in the seal. If thats the case, just make sure you keep the oil level up until you get a new set of bearings installed. If not you can harm the gears then when you do rebuild it, you will have some howling gears.

bradrhale · 04-09-2009, 06:44 AM

SKG makes a seal that rides higher up on the pinion. stemco can give you a wear ring that gets pushed on there. check out a local parts shop and see what options they have that are available to you.

gmctrucks · 04-09-2009, 07:05 AM

Lucas .........................

leolkfrm · 04-10-2009, 05:55 PM

you should not need a new pinion, just the yoke end for the driveshaft

04-07-2009, 05:00 PM	#1
curt 5.7 Senior Member Join Date: Jun 2008 Posts: 52	Diff. Leaking On my 93 gmc the rear diff. is leaking oil from the seal by where the drive shaft bolts to the diff. (forgot what the seal is called), anyway I changed it and it's still leaking but about half of what is was is there any additive I can put in the diff to stop it?Or should I change the seal and coat the edge with silicone or something.The diff was a posi. but I changed it to a limited slip (all I could get).

04-07-2009, 07:17 PM	#4
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 4,300	see if another brand seal runs on the shaft on a little different place, a hardened old seal will cut a light groove, and even a new seal at the same point will leak __________________ 4 wheels move the body 2 wheels move the soul B.W.A.I

04-10-2009, 05:55 PM	#10
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 4,300	you should not need a new pinion, just the yoke end for the driveshaft __________________ 4 wheels move the body 2 wheels move the soul B.W.A.I

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04-07-2009, 06:29 PM	#2
truckabuser Full Member Join Date: Nov 2008 Posts: 24	depends how bad it leaks i guess. if you gotta chase it down with a quart every 100 miles, i'd consider getting something done with it. that's my opinion. oh, called a pinion seal...you know, ring and pinion....ring gear pinion gear...

04-07-2009, 06:38 PM	#3
curt 5.7 Senior Member Join Date: Jun 2008 Posts: 52	I cleaned the vent tude and it seemed fine.Before I changed it, it used about a quart for 1000 miles.Now it will drip about a teaspoon for about 30 miles.But it should not be leaking if I changed it.Did a nice under coating to the box though, the oil is hard to get off.

04-08-2009, 07:17 PM	#5
curt 5.7 Senior Member Join Date: Jun 2008 Posts: 52	I will check too see if there is a grove in the shaft, I was sure I seen one.If not I will get a new seal silcone it in and see what happens.

04-08-2009, 07:53 PM	#6
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 8,025	silicon on that seal is not going to do any good. the shaft has to turn in the seal. the silicon will rub off very quickly. if there is indeed a wear spot on the pinion, some seal manufacturers sell a wear ring that get shoved on there. other solution is to purchase a new pinion. again, if this is indeed the problem.

04-08-2009, 11:01 PM	#7
hotrodpc Senior Member Join Date: Jul 2008 Location: OKC, OK Posts: 3,149	Brad beat me to it. The silicone isn't gonna fix it. I think Leo has the best suggestion. Try a differant brand seal that may ride on the pinion yoke in a differant spot, either before the groove or after doesn't matter. It is also possible your pinion bearing is wore out, and wobbling around alot and chewing up your seal, or wobbling around enough to let there be a gap in the seal. If thats the case, just make sure you keep the oil level up until you get a new set of bearings installed. If not you can harm the gears then when you do rebuild it, you will have some howling gears.

04-09-2009, 06:44 AM	#8
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 8,025	SKG makes a seal that rides higher up on the pinion. stemco can give you a wear ring that gets pushed on there. check out a local parts shop and see what options they have that are available to you.

04-09-2009, 07:05 AM	#9
gmctrucks Senior Member Join Date: Nov 2006 Location: Houston,Texas Posts: 4,033	Lucas .........................