C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Where's the vacuum?

Thread Tools
 
Search this Thread
 
Old Jun 4, 2011 | 02:52 PM
  #1  
luvchevs's Avatar
luvchevs
Thread Starter
Melting Slicks
15 Year Member
 
Joined: Oct 2007
Posts: 2,334
Likes: 8
From: Ontario
Default Where's the vacuum?

My 94 coupe is not blowing cold air out the dash vents.
Base on suggestions from forum members I looked at the check valve that is located on the passenger side of the intake manifold.
I replaced it although the original appears to work. I get vacuum past the check valve.
Went to the vacuum programmer under the dash and don't appear to have vacuum there. The line is almost impossible to follow it runs along the firewall and is buried in wire looms. When we blow compressed air in the vacuum line past the check valve when can feel it come out the connecter that goes into the programmer. This makes us think there isn't an issue with the line?
Why is the vacuum disappearing?
The line that goes into the programmer seems more flexible than the line coming off the check valve, is there a connection somewhere between the check valve and the programmer?
Anyone have a vacuum diagram that might help?

Dave
Reply
Old Jun 4, 2011 | 06:54 PM
  #2  
rodj's Avatar
rodj
Le Mans Master
25 Year Member
 
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Default

If the LT1 is plumbed the same as a L98 ;
downside of the valve is a T (L98 valve is a T as well as check valve ) that supplies vac to the cruise control and the line ultimately ends up at the vac storage ball under the drv side headlight
Reply




All times are GMT -4. The time now is 11:45 AM.

story-0
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years

Slideshow: 10 reasons why the C6 Z06 is still a performance benchmark after 20 years.

By Joe Kucinski | 2026-05-27 17:20:09


VIEW MORE
story-1
How Much Horsepower Every Corvette Engine "LOST" in 1972

Slideshow: How much horsepower every Corvette engine lost in 1972.

By Joe Kucinski | 2026-05-27 16:54:53


VIEW MORE
story-2
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!

Slideshow: How to Protect A Convertible Top: 10 DOs & DON'Ts

By Michael S. Palmer | 2026-04-03 00:00:00


VIEW MORE
story-3
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!

Slideshow: The 10 most explosive Corvettes ever built based on power-to-weight ratio.

By Joe Kucinski | 2026-05-20 07:23:03


VIEW MORE
story-4
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter

Slideshow: From C1 to C8 we compare every Corvette generation by the numbers.

By Joe Kucinski | 2026-05-12 16:54:12


VIEW MORE
story-5
8 Coolest Corvette Pace Cars (and Replicas) of All Time

Slideshow: Some Corvette pace cars became collectible legends, while others perfectly captured the look and attitude of their era.

By Verdad Gallardo | 2026-05-11 09:50:51


VIEW MORE
story-6
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)

Slideshow: Ranking the top 10 Corvette engines by torque output.

By Joe Kucinski | 2026-05-05 11:58:09


VIEW MORE
story-7
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!

Slideshow: A Corvette pace car nearly matching IndyCar speeds sounds exaggerated, until you look at the numbers.

By Verdad Gallardo | 2026-05-04 20:03:36


VIEW MORE
story-8
Top 10 Corvettes Coming to Mecum Indy 2026!

Among a rather large group of them.

By Brett Foote | 2026-05-04 13:56:44


VIEW MORE
story-9
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!

Slideshow: the top 10 things Corvette owners want in the C9 Corvette

By Michael S. Palmer | 2026-04-30 12:41:15


VIEW MORE