engine help ( ml320 w164 )

[MakinaCore]

was looking for the glowplug modual and have found what looks like hoses that connect some were but not sure what they are for or if there should be some sort of clips for them to hold in place
i have left pictures if anyone could help me out thanks

ml320 w164 2006

 

[BlackC55]

Air intake pipes. They just push together with no clips.

 

[MakinaCore]

thanks

 

[MakinaCore]

Air intake pipes. They just push together with no clips.

is it normal for it to have oil in they pipes ?