Jason R Swayden

Where does that little hollow tube go that sits on top of the heater hose water shut off valve? Its in like 3 pieces so I need to know where to route the new one to.

FAUEE

Theres a vacuum line that comes from inside the car, under the passenger dash.

Later years dont have anything from what I understand.

Jason R Swayden

hcbph

Have not looked at this one but something similar is my one Cutlass went to a vacuum port on the heater/ac control. I assume this one is the same.

JrRifleCoach

FWIW Rotting heater cores have been a problem with early C4s from the beginning. By shutting off coolant flow to the heater core causes corrosion and leaks. Later models had this valve removed. IMHO you might consider locking that valve open and forget searching and connecting the vacuum line. I did this in my 86 and didn't notice any temp differences in the cabin during the hot season.

Jason R Swayden

How would one lock the valve open? I'm thinking about wiring the stock vacuum line to wherever the hell it goes (still don't know). But it would be handy to know how to lock it open. Thanks

JrRifleCoach

Heres a pic of the valve with a black cleco I used for testing.
Later replaced with a bolt and nut.

Hot Rod Roy

Are you sure that's the "open" position? Mine works the other way. Vacuum closes the valve, and lack of vacuum opens the valve.



Try it. With the engine running (so you have vacuum), and heater off, what is the valve position? Turn on your heater, and what is the valve position?