are you talking about the crankcase depression valve? there is no filter from stock. i pulled mine and stuck a filter in it.... thats how i discovered my cracked piston ring!

 

we know nothing about your truck.

put some truck info in your signature

 

forgot that i had changed trucks and hadnt changed signature
its a 1994 f250 super cab long bed 7.3 idi turbo 4x4 auto
using around two qts a week:ford:

 

I believe there is supposed to be a CDR on the side of the air box with a down tube into there? Don't have my turbo supplement handy

 

compression test

i feel like an idiot becuase ive owned 4 diesels and dont know, but how do you check the compression on this truck. does this sound normal to use a qt or so a week because of this relief valve?

 

It doesn't sound impossible, a lot of oil actually goes into that thing. They are not impossible to get but I forget what they call them now. If you want to do a custom install with a remote CDR and a different intake you want a GM 6.5 CDR, which has a bracket, a fitted hose, and most importantly, 1" nipples in AND out. The stock unit bolts up against the air box with a washer, and has a nipple on the in (bottom) side which goes to that breather hole.

The CDR functions as an oil separator and as a PCV valve, preventing your intake from drawing crankcase vacuum, which can happen on any diesel with a clogged filter, but especially on turbo diesels. It's not a very big oil sep for such a large engine but it seems to do the job.

You check compression with a diesel compression tester. They work like a gas one but they go into the glow plug hole and they measure higher pressure. Just bring it up to temp first, then it will have no trouble starting. You may have to bring it up to temp to get the glow plug out easily anyway. If you get stuck removing a glow plug, search for glow plug removal article.