84' Vacuum line help
Thread Starter
Pro
Joined: Jun 2013
Posts: 524
Likes: 8
84' Vacuum line help
So I'm trying to make sure all my vacuum lines are routed to the correct spots and I found the vacuum line in the harness behind the distributor which I read was the main vacuum source but over at the heater control valve there is two more lines. One goes to the valve the other has a long hose routed over towards the brake booster. From the diagrams in the FSM it looks like that is the main vacuum source that goes to the 3 way check valve and if it is what is the one behind the Distributor?
Pro
Joined: Jul 2023
Posts: 533
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From: Marysville WA
Post some pics so we can compare. Also check out this recent thread. Lots of diagrams and descriptions (and arguments haha).
https://www.corvetteforum.com/forums...uel-lines.html
https://www.corvetteforum.com/forums...uel-lines.html
Thread Starter
Pro
Joined: Jun 2013
Posts: 524
Likes: 8
I have most of the lines removed and disconnected from when I have the engine out but I was reading the other posts and my front port is plugged and everything feeds out the back. Main thing I’m wondering about is the line behind the distributor in the main harness.
Melting Slicks
Joined: May 2002
Posts: 2,263
Likes: 413
From: Muskogee OK
Cruise-In VI Veteran
The vac line behind the distributor in the main wiring harness feeds the HVAC system it's vacuum source for the control unit to operate the vacuum actuated dampeners.
If you've ever pulled your hair out chasing an idle or stumbling issue, (probably just a 4+3 issue vs autos having the torque converter keeping a little load on the engine vs a free spinning clutch) plug that vacuum source and see if it goes away, indicating a vacuum leak inside the cab
If you've ever pulled your hair out chasing an idle or stumbling issue, (probably just a 4+3 issue vs autos having the torque converter keeping a little load on the engine vs a free spinning clutch) plug that vacuum source and see if it goes away, indicating a vacuum leak inside the cab
Melting Slicks
Joined: May 2002
Posts: 2,263
Likes: 413
From: Muskogee OK
Cruise-In VI Veteran
Correct, I want to say it's fed off the check valve with the 2nd output on it off the drivers side but I haven't messed with anything under the hood in 2 years. Let me find another diagram or picture
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Thread Starter
Pro
Joined: Jun 2013
Posts: 524
Likes: 8
What vacuum source feeds that line? I have the two lines near the evaporator that seem to duck inside the wiring harness one goes to the water valve the other was conected to a hose routed towards the brake booster.
Melting Slicks
Joined: May 2002
Posts: 2,263
Likes: 413
From: Muskogee OK
Cruise-In VI Veteran
I want to say that it's off the check valve line that comes off the side of it at a 90 vs straight thru, as shown in the diagram on 18-4 , but I can't say for sure since it's been to long since I've had hands on it
Thread Starter
Pro
Joined: Jun 2013
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One diagram shows both lines on the pass. Side one to the heater valve and the other going to the vac tee. The other shows the ball and cruise getting the tee connections. Nothing mentioned about the hidden line behind the distributor. I assume some of those diagrams are not accurate. Need to find a intact 84’ and look at it.
Melting Slicks
Joined: May 2002
Posts: 2,263
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From: Muskogee OK
Cruise-In VI Veteran
If mine weren't in the garage at my house that my soon to be ex-wife had me removed from I'd just pop the hood and look. By the time this dang divorce ends and I have my pre relationship '84 back you will probably have gotten an answer though
Drifting
Joined: Nov 2018
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From: USA
Last edited by '78CorvetteS.A.; Today at 04:30 PM.