Question guys I have 2012 silverado and I've noticed that it leaks transmission fluid when it sits for about a week from front u joints area, again it only does it when I don't drive it, do replace them ?

 

Just thinking out loud here....

Transmission fluid leak from the rear of the transmission can be caused by a worn out U-joint. It causes vibration, and can damage the seals at the rear of the transmission, along with other things. Can you tell that it is worn?

Another thought would be that if the vehicle sits for a while, fluid drains slowly from the torque converter, building the level up above the normal level in the transmission pan, and that you have a leak at the rear that only shows once the fluid reaches a certain level.

 

So does that mean I need to replace the converter ?

 

No. I am saying that the seals on the rear of the transmission are leaking up above the shaft coming out to the U-joint. But it takes a while sitting with fluid SLOWLY draining from the torque converter, which holds a lot of the fluid, before it gets above the level of that seal. When running, the fluid is pumping and the level in the pan and bottom of the transmission goes up.

If you think the U-joint is worn, I would replace it, but I would also look at the pan gasket and the output shaft seals and/or bushings. Can you tell exactly where the fluid is leaking out? That's the real question.

 

Is it lifted? Is the driveshaft angle too steep? Could be a small tear in the lip of the seal where it contacts the shaft or a burr in the shaft tearing into the seal, check the seal against the shaft first, never overlook the obvious.