Incontinent Transmission - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bluec10 · 11-13-2004, 11:18 PM

I've got problems with my transmission wetting itself. Ever since I put a new motor in my '76, the transmission leaves a pool of fluid on the garage floor. When I park the truck facing down the driveway, it doesn't leak, so I know the fluid is coming out the back. I put new seals in the speedo gear and a new seal at the end of the transmission. Maybe I bumped something when I was removing/installing the transmission?

So I've done the obvious stuff. What is the next level to attack?

rolson1039 · 11-13-2004, 11:27 PM

gasket around the tail shaft???

Slonaker · 11-14-2004, 12:16 AM

I had that same problem. This fixed it.

http://www.73-87.com/7387garage/drivetrain/yokeleak.htm

Slonaker

piecesparts · 11-14-2004, 12:25 AM

The transmission tailshaft housings have a bushing/seal assembly on the output shaft in front of the rear seal on the outlet. If that is worn, it will leak out the shaft end. In most cases the oil will run down the splines and weep out of the pinhole that is at the end of the yoke (where the u-joint crossmember is). Some people fill the splines with wheel bearing grease to stop this, then there are those of us that will replace the seal and bushing inside to help the leak problem.

86k10 · 11-14-2004, 01:52 AM

It never made sense to me why they needed those seals to start with

and they were only used in the 9" tailshaft version. So my remedy has always been to clean that little weep hole area good and seal it with RTV and never mind that stupid worthless o ring inside. And it doesn't evern require taking out the drive shaft to do it if you have patience.

SanitysBane · 11-14-2004, 01:57 AM

all the 700R4s i've worked on had that too

hotrodhomi · 11-14-2004, 12:40 PM

I had this problem and I took it to a tranny shop. They said my seal was good in the tail shaft but to plug the hole thats in the end of the drive shaft behind the front u-joint. I put a little dab of RTV in there and it stopped.

bluec10 · 11-15-2004, 03:44 AM

Thanks guys. I've spend enough time on the cold, hard garage floor to give the RTV solution a try. I'm just so sick of this stupid thing leaving a mess wherever I park it.

piecesparts · 11-15-2004, 12:31 PM

The principal of the weep hole is to allow for air to move in and out of the tube of the splined part of the yoke. This allows for an easier movement, when the driveline moves with the action of the rear suspension. This way a vacuum is not created on a withdrawal of the shaft and also pressure is not created on an insertion of the shaft. The relatively safe answer to all problems is to plug the hole, or replace the seals and bushing- like it should be. Your Choice.

Slonaker · 11-15-2004, 02:09 PM

Plugging the weep hole is fixing the symptom, not fixing the problem. I did that, but only until I could fix it right. The parts are inexpensive, and it is not difficult to do, why not fix it right?

Slonaker

bluec10 · 11-15-2004, 03:00 PM

If the weep hole is there to prevent a vacuum from forming, what is the role of the vent hole on the top of the transmission? I assume that the weep hole is ventilating just the tail housing if the weep hole is that important for ventilation.

SanitysBane · 11-15-2004, 06:43 PM

correct, just the tail housing, the vent tube on top is for the pump actually

piecesparts · 11-15-2004, 10:34 PM

Think of the output shaft and the splined yoke as athe same thing as a shock absorber. If you restrict the flow of air into and out of the weep hole you will have to get the air that is in the tube out of it some way. If you are pulling the splined yoke off of the shaft it will act like a shock that is resisting the removal of the outer shaft housing.

11-13-2004, 11:18 PM	#1
bluec10 Registered User Join Date: Apr 2002 Location: Manitoba, Canada Posts: 663	Incontinent Transmission I've got problems with my transmission wetting itself. Ever since I put a new motor in my '76, the transmission leaves a pool of fluid on the garage floor. When I park the truck facing down the driveway, it doesn't leak, so I know the fluid is coming out the back. I put new seals in the speedo gear and a new seal at the end of the transmission. Maybe I bumped something when I was removing/installing the transmission? So I've done the obvious stuff. What is the next level to attack? __________________ Present: 2015 Tacoma. Yeah, not a GM, but I love it. 1969 GMC 32,000 - fix, drive, relax, fix... 2019 BMW R1250 GSA - Yahoooooooo 1979 Honda GL 1000 - retro touring at its best. Past: '05 Sierra 4x4 - Had 270,000 KM and running well when it was written-off by a stop sign runner. '94 F-150 from the "F word" company. I'll admit it...good truck. Sold what was left of it for $800 to a guy who came to pick it up at 11:00 PM with cash in hand. Hmm. '79 Sierra Grande (Black) organ donor - perfect rebuildable 4-bolt 350 and a good TH350. '76 Sierra Grande (Orange) - hate isn't too strong a word. Kid who bought it turned it into a hot rod. '68 C-10 R.I.P. - Dad's old truck...too far gone to resurrect. '59 C-50 - with hoist. Truck is gone, wife isn't. Nuff said. Last edited by bluec10; 11-13-2004 at 11:20 PM. Reason: Unclear wording

11-13-2004, 11:27 PM	#2
rolson1039 Registered User Join Date: Oct 2002 Location: NJ Posts: 404	gasket around the tail shaft??? __________________ so many trucks so little time!!!

11-14-2004, 12:16 AM	#3
Slonaker Insert Witty Text Here Join Date: Oct 2002 Location: San Antonio, TX Posts: 3,415	I had that same problem. This fixed it. http://www.73-87.com/7387garage/drivetrain/yokeleak.htm Slonaker __________________ '86 Chevy C10 (Sold 04/19/13 ) Stock '01 Silverado

11-14-2004, 01:52 AM	#5
86k10 Registered User Join Date: Feb 2003 Location: Bertrand, Nebraska Posts: 355	It never made sense to me why they needed those seals to start with and they were only used in the 9" tailshaft version. So my remedy has always been to clean that little weep hole area good and seal it with RTV and never mind that stupid worthless o ring inside. And it doesn't evern require taking out the drive shaft to do it if you have patience. __________________ 98 Neon 97 Grand Prix GT 02 Grand Prix 40th Anniv. 86 GMC 5.0 77 Olds 98 6.6 REAL AMERICANS, DRIVE AMERICAN

11-14-2004, 01:57 AM	#6
SanitysBane Registered User Join Date: May 2004 Location: Lubbock, Texas Posts: 2,121	all the 700R4s i've worked on had that too __________________ '96 Nissan Pathfinder '02 Firebird Trans Am. '88 K5 Blazer

11-14-2004, 12:25 AM	#4
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	The transmission tailshaft housings have a bushing/seal assembly on the output shaft in front of the rear seal on the outlet. If that is worn, it will leak out the shaft end. In most cases the oil will run down the splines and weep out of the pinhole that is at the end of the yoke (where the u-joint crossmember is). Some people fill the splines with wheel bearing grease to stop this, then there are those of us that will replace the seal and bushing inside to help the leak problem.

11-14-2004, 12:40 PM	#7
hotrodhomi Registered User Join Date: Apr 2004 Location: Sacramento Posts: 3,737	I had this problem and I took it to a tranny shop. They said my seal was good in the tail shaft but to plug the hole thats in the end of the drive shaft behind the front u-joint. I put a little dab of RTV in there and it stopped.

11-15-2004, 03:44 AM	#8
bluec10 Registered User Join Date: Apr 2002 Location: Manitoba, Canada Posts: 663	Thanks guys. I've spend enough time on the cold, hard garage floor to give the RTV solution a try. I'm just so sick of this stupid thing leaving a mess wherever I park it. __________________ Present: 2015 Tacoma. Yeah, not a GM, but I love it. 1969 GMC 32,000 - fix, drive, relax, fix... 2019 BMW R1250 GSA - Yahoooooooo 1979 Honda GL 1000 - retro touring at its best. Past: '05 Sierra 4x4 - Had 270,000 KM and running well when it was written-off by a stop sign runner. '94 F-150 from the "F word" company. I'll admit it...good truck. Sold what was left of it for $800 to a guy who came to pick it up at 11:00 PM with cash in hand. Hmm. '79 Sierra Grande (Black) organ donor - perfect rebuildable 4-bolt 350 and a good TH350. '76 Sierra Grande (Orange) - hate isn't too strong a word. Kid who bought it turned it into a hot rod. '68 C-10 R.I.P. - Dad's old truck...too far gone to resurrect. '59 C-50 - with hoist. Truck is gone, wife isn't. Nuff said.

11-15-2004, 12:31 PM	#9
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	The principal of the weep hole is to allow for air to move in and out of the tube of the splined part of the yoke. This allows for an easier movement, when the driveline moves with the action of the rear suspension. This way a vacuum is not created on a withdrawal of the shaft and also pressure is not created on an insertion of the shaft. The relatively safe answer to all problems is to plug the hole, or replace the seals and bushing- like it should be. Your Choice.

11-15-2004, 02:09 PM	#10
Slonaker Insert Witty Text Here Join Date: Oct 2002 Location: San Antonio, TX Posts: 3,415	Plugging the weep hole is fixing the symptom, not fixing the problem. I did that, but only until I could fix it right. The parts are inexpensive, and it is not difficult to do, why not fix it right? Slonaker __________________ '86 Chevy C10 (Sold 04/19/13 ) Stock '01 Silverado

11-15-2004, 03:00 PM	#11
bluec10 Registered User Join Date: Apr 2002 Location: Manitoba, Canada Posts: 663	If the weep hole is there to prevent a vacuum from forming, what is the role of the vent hole on the top of the transmission? I assume that the weep hole is ventilating just the tail housing if the weep hole is that important for ventilation. __________________ Present: 2015 Tacoma. Yeah, not a GM, but I love it. 1969 GMC 32,000 - fix, drive, relax, fix... 2019 BMW R1250 GSA - Yahoooooooo 1979 Honda GL 1000 - retro touring at its best. Past: '05 Sierra 4x4 - Had 270,000 KM and running well when it was written-off by a stop sign runner. '94 F-150 from the "F word" company. I'll admit it...good truck. Sold what was left of it for $800 to a guy who came to pick it up at 11:00 PM with cash in hand. Hmm. '79 Sierra Grande (Black) organ donor - perfect rebuildable 4-bolt 350 and a good TH350. '76 Sierra Grande (Orange) - hate isn't too strong a word. Kid who bought it turned it into a hot rod. '68 C-10 R.I.P. - Dad's old truck...too far gone to resurrect. '59 C-50 - with hoist. Truck is gone, wife isn't. Nuff said.

11-15-2004, 06:43 PM	#12
SanitysBane Registered User Join Date: May 2004 Location: Lubbock, Texas Posts: 2,121	correct, just the tail housing, the vent tube on top is for the pump actually __________________ '96 Nissan Pathfinder '02 Firebird Trans Am. '88 K5 Blazer

11-15-2004, 10:34 PM	#13
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Think of the output shaft and the splined yoke as athe same thing as a shock absorber. If you restrict the flow of air into and out of the weep hole you will have to get the air that is in the tube out of it some way. If you are pulling the splined yoke off of the shaft it will act like a shock that is resisting the removal of the outer shaft housing.

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