Cross Member Bracket "Cap Popped Off and Can't Get It Back On"

[Dino1956]

I have a slight oil pan leak. My Left Crossmember Cap Popped Off and won't go back on because of Oil I guess. If I try to pop it in it just pops back out. Guess I need a new one.
Is it bad to drive around without the Cap on? I'm afraid debris will get inside. Thanks in advance.

CAP, MEMBER BRACKET
Part Number: B25D34819A