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Vacuum Leak

Posted: 10/23/08 6:55pmMessage 1 of 20

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tsmith1499

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mount airy, MD - USA

Joined: 8/27/2006

Posts: 71

Vette(s): 1981 Charcoal Met., Silver Interior, Gymkhana Suspension, 27K original miles. It's my daily driver.

Where is the best place to start looking for a vacuum leak that affects the heater and defroster door from changing? Once in awhile I can get the defroster to blow on the windshield, but mostly it blows on the floor and I just noticed today that I hear a vacuum sound through the defroster vent when it's on heat. The sound goes away when put on vent or defrost. What a time to start acting up, just when it starts to get cold. Thanks, Tom

1981 Corvette, 26K original miles, charcoal gray, gymkhana suspension, AM/FM/8 track.

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Vacuum Leak

Posted: 10/23/08 7:05pmMessage 2 of 20

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Ron 78

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BINGHAMTON, NY - USA

Joined: 7/19/2003

Posts: 3825

Vette(s): ......

Whats that?a vacuum leak on a Corvette,impossible

C3VR Lifetime Member #93

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Vacuum Leak

Posted: 10/23/08 7:14pmMessage 3 of 20

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acplus

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Orillia, Canada

Joined: 6/23/2008

Posts: 558

Vette(s): 1972, 1980

Remove the glove box door and inside box, screws are on the side for the box, this will give you access to the top vacumn lines, remove the side panels on the center shifter console, don't forget the screws at the back beside the seat bottom side, this will give you access to the lower lines, check to see if one of the modules hasn't been unplugged or cracked.

John

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Vacuum Leak

Posted: 10/24/08 5:32amMessage 4 of 20

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deeboy59

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visalia, CA - USA

Joined: 10/27/2006

Posts: 641

Vette(s): 1981 red with silver interior,350(L-81), 350TH, glass t-tops, aluminium rims, 1980 Black/ Black int., 350 GM crate engine/350TH, 1976 black/ saddle int., L-82 w/headers, holly carb, Hypertech ignition

I have the same problem on my '81. I found it to be the vac. actuator for the defroster door which is mounted up under the dash on the drivers side. On mine, the diaphram had actually ruptured and was leaking air. At first, it continued to work, but then it slowly got worse and worse and you could here more and more air wissling thrjough the vent. Beings I'm in California, I dont need the defroster that much, so I just disconected and pluged the line and put that on the repair list ....

HTH

Daniel

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Vacuum Leak

Posted: 10/24/08 9:23amMessage 5 of 20

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anips

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sonoma, CA - USA

Joined: 8/9/2002

Posts: 784

Vette(s): 72 LT-1 AC coupe,69 l-36 coupe

If you have access to a electric vac pump hook it to the hose that comes from the vac tank, that way you can check everything without starting the engine to build vac, a friend of mine had a vac pump he used to evacuate AC sys's

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Vacuum Leak

Posted: 10/24/08 5:10pmMessage 6 of 20

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acplus

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Orillia, Canada

Joined: 6/23/2008

Posts: 558

Vette(s): 1972, 1980

Any luck?

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Vacuum Leak

Posted: 10/24/08 7:32pmMessage 7 of 20

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tsmith1499

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mount airy, MD - USA

Joined: 8/27/2006

Posts: 71

Vette(s): 1981 Charcoal Met., Silver Interior, Gymkhana Suspension, 27K original miles. It's my daily driver.

Haven't had a chance to look at it yet. Hopefully this weekend. I will report on what I found. I had another problem crop up yesterday. Coolant leak under front drivers side. At least that's where it's dripping from. Need to check them both out. If it's not one thing it's another.

Thanks for all the ideas, Tom

1981 Corvette, 26K original miles, charcoal gray, gymkhana suspension, AM/FM/8 track.

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Vacuum Leak

Posted: 10/24/08 9:41pmMessage 8 of 20

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Gale Banks 80

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Joined: 9/8/2005

Posts: 241

Vette(s): 1980 with a Banks Twin Turbo 1969 Convert Big Block 1996 Grand Sport Convert

Go to Home depot and Buy a long Hose that You can run outside Your garage to another car. Plug in both cars and start the one outside. You will now be able to Here any Vacume leak and trace it down with out any Engine Noise.

My Car...PIC 1 PIC 2

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Vacuum Leak

Posted: 10/25/08 2:54amMessage 9 of 20

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terntes

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Little Rock, AR - USA

Joined: 7/10/2007

Posts: 123

Vette(s): 1982 Collector Edition

I have the same defroster problem with my '82. I've checked everything except the diaphragm, which I am sure is the culprit. I can hear a return spring over-riding the initial vacuum to the diaphragm and slowly the defroster turns to a heater. I haven't fixed mine yet either, but this year for sure. Don't give up, these fine cars need a lot of TLC, but they are worth it.

terntes

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