WASHINGTON -- The launch of space shuttle Endeavour has been postponed 24 hours because of unexpected work to fix a leak in the crew cabin, NASA announced Friday.

Endeavour is originally scheduled to launch on August 7, and now the new launch is targeted for Wednesday, August 8, at 6:36 p.m. EDT (2236 GMT).

An earlier leak in Endeavour's crew cabin has been fully resolved. The problem was traced to one of two positive pressure- relief valves that ensure the cabin does not become over- pressurized.

The suspect valve was removed and replaced with a valve from shuttle Atlantis. Another round of testing was successfully completed Thursday night, with no leakage detected, said NASA.

The additional day will provide the shuttle processing team more time to complete routine work before liftoff and allow the countdown to begin at 8:00 p.m. EDT on Sunday.

Led by Commander Scott Kelly, the sever-member flight crew of Endeavour is set to arrive late Friday at Kennedy Space Center in Florida. They will spend the remaining days until launch undergoing final prelaunch preparations.