Liverpool will face English champions Chelsea in the semi-finals after the latter overcame Spanish giants Valencia.
The Reds' boss Rafael Benitez opted to rest skipper Steven Gerrard and right-back Steve Finnan as their progress was almost guaranteed following the 3-0 first-leg victory in Holland.
The visitors produced an early scare after three minutes through Jefferson Farfan, whose header from Philip Cocu's cross was tipped over by Liverpool keeper Jose Reina.
Liverpool's Welsh striker Craig Bellamy had to be replaced shortly after due to an injury, making a way for veteran frontman Robbie Fowler.
In the 26th minute, Crouch connected with Jermaine Pennant's cross to send a bouncing shot that was blocked by PSV keeper Gomes.
PSV defender Dirk Marcellis was sent-off four minutes past the hour mark for a challenge on Boudewijn Zenden.
England international Crouch capitalized four minutes later when he tapped-in from close-range after connecting with Fowler's cross.