Incontinent Transmission
 

:mad: 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?

:gmc:

gasket around the tail shaft???

I had that same problem. This fixed it.

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

Slonaker

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.

It never made sense to me why they needed those seals to start with :bs: 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. :bowtie:

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

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.

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.

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.

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

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.

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

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.