Where Does This Hose Go?

[Allen N.]

I have a small black hose coming out of the firewall in back of the distributor on my 70 LS5. It has blue painters tape on it in the picture below. It is 21 inches long sticking out of the firewall. Does anyone know where this hose is supposed to go?

Thanks,
Allen

Hose thru Firewall.jpg

[Gary S.]

Re: Where Does This Hose Go?

Probably not going to help but on my 72 LT-1 that hose goes along the firewall up to a T fitting just to the outboard side of the right hand vacuum actuator. Mine appears to be unmolested and probably original?

[Bill B.]

Re: Where Does This Hose Go?

Allen,

Mine sticks out approx 5" from the firewall and tucks behind the RH ignition shielding. Does not connect to anything.

It originates from the top connection of the Windshield wiper vacuum switch on the passenger wiper in the wiper cowl area.

It apparently is a vent hose to atmosphere for the wiper door vacuum system. I am surprised there is no filter at the end of that hose ...

[Bill B.]

Re: Where Does This Hose Go?

On a second look at your picture, it is unclear if your hose exits the firewall very close to your blue tape.

If it does, then ignore my previous post above. My 1970 does not have a hose exiting the firewall in that location.

If, however, it originates from the 3-hose grommet from the cowl, then OK.

Can't exactly tell from the pic ...

[Mark E.]

Re: Where Does This Hose Go?

Allen,

On my '70 LS5 with AC, the AC wiring harness (not vacuum lines) go through this hole. The diagram in AIM Section C60 isn't real clear but suggests the AC harness passes through the bulkhead in this area.

Your car does not have AC, so maybe this hole is used for another purpose?

To the left of this hole (as you're facing it) is another pass-through for the HVAC vacuum lines. I don't see that hole in your photo but it may be hidden by your harness and vacuum lines. Again, maybe for AC only?

Wish I could help more.

Have you tried applying vacuum to this line to see what it does? That may help figure out where to attach it.

BTW, your engine compartment looks great.

[Mark E.]

Re: Where Does This Hose Go?

Allen,

Mine sticks out approx 5" from the firewall and tucks behind the RH ignition shielding. Does not connect to anything.

It originates from the top connection of the Windshield wiper vacuum switch on the passenger wiper in the wiper cowl area.

It apparently is a vent hose to atmosphere for the wiper door vacuum system. I am surprised there is no filter at the end of that hose ...

Bill,

I think you're pointing out another nearby pass-thru hole for vacuum lines to the wiper door system.

[Ron G.]

Re: Where Does This Hose Go?

Allen,

I am not sure of the hose you are in question about, but there is a short black hose that comes out of the right-hand corner in the engine compartment that is a vent hose and does not connect to anything. Email me your email address and I will send you a pic of my original to see if it is the hose that you are concerned about. My email address is: RgodutiLT1@yahoo.com.

[Owen L.]

Re: Where Does This Hose Go?

My '72 LS-5 w/AC has two hoses coming out of that location on the firewall. One of the hoses goes back through the firewall near the wiper door switch and into the wiper arm area; the other hose connects to a very tiny Tee fitting in the large vacuum hoses by the right hood latch. The first looks like it's for a vent plenum in the cowl side drain. The second hose also has something to do with the climate control.

These illustrations are from the C60 A/C pages of the '72 AIM.
Screen Shot 2022-04-27 at 5.15.07 PM.jpgScreen Shot 2022-04-27 at 5.15.23 PM.jpg

[Allen N.]

Re: Where Does This Hose Go?

I was at an NCRS event today in Austin and found the hose I am talking about going into a "T" in the large yellow striped vacuum hose by the windshield wiper control valve. This was on a 70 small block car, but a master judge there said it was also typical for a big block. Below is a picture of the hose with a clip on the small hose. My line has an identical clip and the length of my hose is correct to go to this location.

IMG_20220611_112201881_HDR.jpg

[Owen L.]

Re: Where Does This Hose Go?

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[Allen N.]

Re: Where Does This Hose Go?

Thank you Owen. I will see if I can find the one that came on the car.