93 K3500
 

Curious if anyone could tell me what the purpose of that gold diapram on the passinger side valve cover. It also has a tube from it to the intake tube. The reason I ask is I am building a intake tube and needed to know how important it is and if i need to reinstall it or I could bypass it. Thanks for any help.

its called a cdr valve. since diesels do not create vaccum they need some way of getting blowby out of the engine. this creates a pressure difference which sucks the blowby out and into the air intake so it can be burned again. you can vent it into the atomsphere but dont take it completely ouy

run a line to blow it out of the motor