How can I test the input shaft seal?

[MR_Loyale]

I have my Loyale transmission (TM70F) completely out of the car and it is nicely clean. And it wasn't removed simply to clean it up. I wanted it out and clean because I have the engine out and if you are going to potentially screw things up, well I believe one should try to be thorough about it, right? Besides my hourly rate for messing things up is much less than a professional mechanic would charge so really I am saving money.

 

Seriously though, I question the integrity of the input shaft seal because upon removal of the engine, I noticed the transmission half of the bell housing was all greasy. In fact it had become so greasy that a black greasy fluid was seeping through the joint there where the transmission case meets the engine bell housing. I imaging it was being thrown off by the input shaft or the clutch release bearing.

 

Despite the excellent writeup by GLoyale on front seal replacement, if not absolutely necessary I would rather not crack open the transmission.  I have nightmares of lifting open one half of the case and springs and retainers exploding out all over the ground never to be located and thus rendering the transmission suitable only for recycling, a conversational floor lamp or a homemade spit roaster for a side of beef. And while I love a good barbecue just as much as the next fellow, I still need this transmission to haul my carcass from the West Coast to the East and back again.

 

What I need is a proof positive method to test the input shaft seal while the transmission is out of the car. The gear oil is still in the transmission. The nearest "test" I have come up with is to stand the transmission vertically and spin the input shaft by hand. Of course I plugged the dip stick tube so that the oil would not run out. No oil came out if the input shaft. It passes my dumb test but that is probably not saying much.

 

Does this test seem reasonable or is there another clever way someone can tell me?  Any transmission specialists out there?