Vacuum Test
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Joined: Jun 2013
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Vacuum Test
A while ago I read that a simple vacuum test was to shut the engine down and turn on the headlights. If they opened and closed the system had no leaks. I tried it today and the headlights opened fully but would not close. Does this mean I have a leak? The car seems to run fine - no apparent problems. Could someone else try this and see what their results are. Thanks.
Team Owner
Joined: Jan 2007
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From: Southern Cal Ca
St. Jude Donor '22
A while ago I read that a simple vacuum test was to shut the engine down and turn on the headlights. If they opened and closed the system had no leaks. I tried it today and the headlights opened fully but would not close. Does this mean I have a leak? The car seems to run fine - no apparent problems. Could someone else try this and see what their results are. Thanks.
will be enough to open lights,
if no leaks.
to close depends on amount of reserve and amount of vac needed.
when perfect i could get a half close
i will repeat that a good vac gauge and hand held vac pump is a must when owning a vette with vac systems.
plus the benefit of a gauge to diagnose engine running.
Team Owner
Joined: Sep 2006
Posts: 31,202
Likes: 4,287
From: Westminster Maryland
Hi T,
Did you use the headlight switch to test the headlight doors?
You might consider using the headlight door vacuum override switch mounted below the steering column to test the vacuum supply for the headlights.
With the engine shut off there should typically be enough vacuum in the storage tank to open and close the doors at least once.
Pulling the **** down opens the doors and pushing it back up closes them.
The same thing can be done to test the wiper door using the wiper door vacuum override switch.
Regards,
Alan
Did you use the headlight switch to test the headlight doors?
You might consider using the headlight door vacuum override switch mounted below the steering column to test the vacuum supply for the headlights.
With the engine shut off there should typically be enough vacuum in the storage tank to open and close the doors at least once.
Pulling the **** down opens the doors and pushing it back up closes them.
The same thing can be done to test the wiper door using the wiper door vacuum override switch.
Regards,
Alan
Last edited by Alan 71; Mar 18, 2018 at 02:00 PM.
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
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Stop doing that before you break it!
Pop the hood and do some investigating.
Cut the ends off a half inch or so of each line to assure a good no leak fit.
Your results are typical for an old Corvette.
If you are into it use this guide to check each part.
http://www.corvette-101.com/vacuum.htm
The heat controls also use vacuum and that is the next area to check.
Cut the ends off a half inch or so of each line to assure a good no leak fit.
Your results are typical for an old Corvette.
If you are into it use this guide to check each part.
http://www.corvette-101.com/vacuum.htm
The heat controls also use vacuum and that is the next area to check.
Thread Starter
Advanced
Joined: Jun 2013
Posts: 87
Likes: 12
Hi T,
Did you use the headlight switch to test the headlight doors?
You might consider using the headlight door vacuum override switch mounted below the steering column to test the vacuum supply for the headlights.
With the engine shut off there should typically be enough vacuum in the storage tank to open and close the doors at least once.
Pulling the **** down opens the doors and pushing it back up closes them.
The same thing can be done to test the wiper door using the wiper door vacuum override switch.
Regards,
Alan
Did you use the headlight switch to test the headlight doors?
You might consider using the headlight door vacuum override switch mounted below the steering column to test the vacuum supply for the headlights.
With the engine shut off there should typically be enough vacuum in the storage tank to open and close the doors at least once.
Pulling the **** down opens the doors and pushing it back up closes them.
The same thing can be done to test the wiper door using the wiper door vacuum override switch.
Regards,
Alan
Team Owner
Joined: Sep 2006
Posts: 31,202
Likes: 4,287
From: Westminster Maryland
Hi t,
If the hoses are all the original hoses you might try clipping about 3/8" off each end of each hose.
There's USUALLY enough length to do this, AND, it gives the hose a NEW sealing surface on the nipple or pipe it slips on to.
MIGHT stop a slow leak down!
Regards,
Alan
If the hoses are all the original hoses you might try clipping about 3/8" off each end of each hose.
There's USUALLY enough length to do this, AND, it gives the hose a NEW sealing surface on the nipple or pipe it slips on to.
MIGHT stop a slow leak down!
Regards,
Alan
Last edited by Alan 71; Mar 19, 2018 at 02:21 PM.
