Suspected lower unit leak please explain what is happening

" This week end, i fond out th

" This week end, i fond out that some creamy looking water was comming out of the lower unit when i took the motor out of the water. I was comming out from were the water usually comes out when you remove the motor from the water. I decided to remove the lower unit and i found out that the ousing was full of this creamy stuff. I did check the seals. They look OK, I pressurise the unit and it did not seams to leak with 18 psi. Is it possible that the seals are good when the engine is not running and then fail when in operation?
For the moment i can't see what else could be the problem. Could the problem be somewere else?
If someone could tell me how i could be sure of it i would apreciate it a lot.
Regards

Luc "

"Luc.... Drain the unit, then

"Luc.... Drain the unit, then pressurize with 7 to 12 pounds (no more than that). Move the propshaft and driveshaft around, back and forth etc. Listen and look carefully. The leak should show up.

Joe "

" i dont know what kind of mot

" i dont know what kind of motor you have, but on some mercury you might also want to check your -shift-shaft seals too. while you have it under pressure go from forward to reverse, in some cases the shift shaft itself could be worn down until it wont hold a seal leaving you with replacement or building up and machining the shaft. "