Bagpype

I am replacing every vacuum hose for my headlight system on my 1978. On the pic you can see where some degenerate idiot PO decided that he would make a little loopty loop with the small vacuum line that is attached to the small side of the 3 way connector going into the vacuum check valve. What is this line supposed to attach to and where is it located? any help will be really greatly appreciated.

oldalaskaman

on the right of your picture, is that a vacuum plug? right next to the dist shield.

Easy Mike

Cruise control vacuum relay would be my guess, but that's only a guess. Do you have the assembly instruction manual (AIM)? If the "loop" is supposed to be there, the AIM would show it.

I won't be able to check the AIM until this evening.

Bagpype

Mike if you could check your aim that would be awesome. I don't have one yet. That hose on the top right was cut by a previous owner, I think I know where that one goes. I don't have cruise control. It may be some heater control thing but I still don't know where it goes.

Camivette

I'll check when I get home if you haven't gotten an answer

Easy Mike

I'll check. I tend to agree with you: looks like a PO fix. The two lines from the check valve appear to be correct. The big one is for headlight vacuum; small one routes through the firewall to the headlight override switch and might tee to the HVAC controls.

KLUTZ

http://fedbizoppssearches.com/CFImag...uumDiagram.jpg


I agree that it may be for the climate control system. I just looked at my '79 and it appears such, but the hose on mine seems smaller then the one in your picture...

Easy Mike

That gets my vote. Should run toward the distributor and grommet in the firewall. (Heat Cont Hose Asm on the AIM page)


Through the firewall and should connect to the HVAC hoses (callout #6).


The optional cruise control used a separate vacuum line and a different fitting on the manifold.

Bagpype

Mike that rocks! Thank you so much. Does the hose go through the firewall through the same grommet that the headlight vacuum hoses go through?

KLUTZ

The one on the left. Two of the tubes go through it.

BKarol

like my 78. The hose also appears much smaller than your loopty loop. Good luck.

Bagpype

Yeah thanks to klutzs pic i see what happened. That hose was loose in my engine compartment and i removed it. I have it still, small white hose kind of plasticy material no?

pwcheenie

I just finished replacing the heater core in my 1980 vette. I traced all the vacume hoses to be sure they were installed correctly. That hose is the supply for the heater and ac control selector. It supplies vacume to open various dampers in the system. It also supplies vacume to close the valve that supplies water for the heater core. I would guess that your heating system does not work and the car blows out hot air all the time.

Bagpype

Lol, i wish it blew hot air all the time. I cant get the blower to turn on at all! But that is a problem i havent looked deeply into yet. Btw, where does the hose attach to inside the car?

pwcheenie

The hose should be a small diameter solid black plastic hose with no color stripe on it. This is the vacume supply to the distribution valve that is located on the back of the heat control selector, that is mounted on the consol. You will have to take the carpered side panels off the center consol to see it. It has 5 hoses attached to it. 4 have colored stripes on them. If you have a piece of this black hose, it may have been cut off. I woud find the other end coming from the valve and try to reattach it with a sleeve.
Look on the engine side of the firewall first. 3 hoses go thru the firewall. Trace the solid black hose that goes behind the distributor to this looped
hose configuration that you show.