So I pulled the CDR valve on my 91 and found out there is NO diaphragm left in it at all. How bad is this and what are the repercussions? I can't afford a new valve right now, should I install a road draft tube for now or just leave it be until I can get a new one?

 

It'll probably just use more oil than otherwise... about what you are using now.
Why? Because it's sucking in oil vapor and burning it(which it does to some extent with a working CDR), but it'll do it worse because it won't close down at higher RPMs where there is more suction.

 

Which is kind of what I expected. So it sounds like it's no big deal to leave it in place until I can afford a new one then. Thank you!

 

Are you sure the diaphragm is gone? It rests against the back of the valve and the default position it wide open both ways:

 

No I guess I'm not sure then. I looked as best as I could and couldn't see the diaphragm but I figured since I could blow through it freely it was probably bad. I expected it to default to closed.

 

the CDR only works well with stock like filter assembles, as the engine operates unburnt fuel and combustion gases leak passed the rings, when not removed they condense on internal surfaces and break down the oil, good venting is always a plus, road draft tubes are a alternative when modified intake systems are used, some persons believe that the gases returned buy the CDR will hurt combustion as they have a lower oxygen content, IMO that it does not. the CDR was also installed to keep oil smell and fumes, from stinking up the vehicle