headlight vacuum problem found, still have a ?
Thread Starter
Burning Brakes
Joined: Nov 2000
Posts: 896
Likes: 0
From: Lafayette, Indiana
St. Jude Donor '05-'08
headlight vacuum problem found, still have a ?
I have been working on the vacuum system for months now, and I just found the problem tonight. I have already installed all new vacuum hoses and was about to spen $160 on new relay valves. But then, with the engine running, I unplugged all the hoses and felt them, to check for vacuum. I noticed I was getting extremely poor vacuum from the hose coming from the vacuum reserve tank. (in the 77, its practically to whole front bumper). Then I unplugged the source hose going into the tank and I had great vacuum. So I hooked the source line directly to the relay valve and my headlights worked!!!!!
This is my question. Would it be ok if I were to split the source line and connect it directly to my relay valves, completely ignoring the reserve tank? If I remember right, the reserve tank is only there to supply vacuum to the system with the engine is off. Could I just ignore it?
This is my question. Would it be ok if I were to split the source line and connect it directly to my relay valves, completely ignoring the reserve tank? If I remember right, the reserve tank is only there to supply vacuum to the system with the engine is off. Could I just ignore it?
Thread Starter
Burning Brakes
Joined: Nov 2000
Posts: 896
Likes: 0
From: Lafayette, Indiana
St. Jude Donor '05-'08
Re: headlight vacuum problem found, still have a ? (Graemeinvette)
because you cant. it is incorporated into the bumper. to fix or replace it you have to remove the whole front clip. Or you can but two '80 replacement canisters. But I'm a freshman at Rose-Hulman and am a little short on money. So I see the easy fix out...for now. Do I really need the vacuum tank if I dont use everything while the engine is running?
Melting Slicks
Joined: Aug 2000
Posts: 2,310
Likes: 1
Re: headlight vacuum problem found, still have a ? (jonny4523)
From what I've read in the past, the answer to your question is YES.
When you have the opportunity, you may want to check the "tank" for pin holes or cracks that may be able to be welded.
[Modified by jerryp58, 6:45 AM 6/20/2003]
When you have the opportunity, you may want to check the "tank" for pin holes or cracks that may be able to be welded.
[Modified by jerryp58, 6:45 AM 6/20/2003]
Melting Slicks
Joined: Nov 2001
Posts: 2,668
Likes: 43
From: Eastern US XX
Re: headlight vacuum problem found, still have a ? (jonny4523)
Do I really need the vacuum tank if I dont use everything while the engine is running?
You should fix or replace the vacuum reservoir!
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Re: headlight vacuum problem found, still have a ? (jonny4523)
jonny, given your financial circumstances, either find the leaks in the rusty tank/frame member, repair with some epoxy, OR, simpler yet, just run it directly and forget about the tank completely, i'ts not all THAT critical to the system...the lack of holding ability IS though, what happens is a continuous vacuum leak, bad for engine operation.....
GENE
GENE
Thread Starter
Burning Brakes
Joined: Nov 2000
Posts: 896
Likes: 0
From: Lafayette, Indiana
St. Jude Donor '05-'08
Re: headlight vacuum problem found, still have a ? (pws69)
Do I really need the vacuum tank if I dont use everything while the engine is running?
The problem is that you ARE using everything when the engine is running. In a total vacuum system (like we have), "vacuum device on or off" has nothing to do with using or not using vacuum - both conditions use vacuum. Stated simpler, vacuum opens, vacuum closes, AND vacuum CONTROLS.
The problem is that you ARE using everything when the engine is running. In a total vacuum system (like we have), "vacuum device on or off" has nothing to do with using or not using vacuum - both conditions use vacuum. Stated simpler, vacuum opens, vacuum closes, AND vacuum CONTROLS.
I'm sorry. You misunderstood me. I meant that I do not use anything while the engine is off. I am always using stuff (the headlights) while the engine is on. I thought that the only reason the tank was there was to supply vacuum so that the lights while still move up and down while the engine was off.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
You can bypass the vacuum tank!
After you shut off the engine you will not be able to raise (or lower) your headlights. I believe the vacuum tank is supposed to give you one cycle of opening/shutting the headlights with the engine off. The only really practical use for this is to lower your lights if you forget to shut them off BEFORE you shut your engine off..... no big deal, right?
With the engine running, you may find the headlights rise very slowly if you are at WOT :lol: . I think you will be hard pressed to notice any difference with the tank bypassed. I dont think your headlights will be popping up and down... try it and let us know. :) MJ
After you shut off the engine you will not be able to raise (or lower) your headlights. I believe the vacuum tank is supposed to give you one cycle of opening/shutting the headlights with the engine off. The only really practical use for this is to lower your lights if you forget to shut them off BEFORE you shut your engine off..... no big deal, right?
With the engine running, you may find the headlights rise very slowly if you are at WOT :lol: . I think you will be hard pressed to notice any difference with the tank bypassed. I dont think your headlights will be popping up and down... try it and let us know. :) MJ
Le Mans Master
Joined: Jun 2002
Posts: 8,339
Likes: 24
From: I can walk to MA
Re: (MNJack)
You should be fine - T-ing it off. There should be an inline check valve
somewhere. If this is in place, then variations of vacuum pressure should go
unnoticed. Unless - like MJ says, you want to raise/lower the headlights while
under WOT .
:seeya
somewhere. If this is in place, then variations of vacuum pressure should go
unnoticed. Unless - like MJ says, you want to raise/lower the headlights while
under WOT .
:seeya