1972 Corvette with Vacuum leak at the headlight switch

[Christopher R.]

After completing the installation of entirely new wiring for my entire corvette project and getting all of the electrics to work, I now have to chase Vacuum issues. I have a new headlight switch and when I switch on the headlights, the headlights work, dash lights work and dim properly, but there appears to be a vacuum leak (quite noticeable noise wise) at the switch when fully engaged. Along with the replacing the electrics (and being the car has been restored) all of the vacuum components (hoses and actuators) have been replaced as well.

Any suggestions (aside from a potentially cheap switch) that would trigger a large vacuum leak at the switch even when the hoses are new and appear to be tight? Maybe the hoses are backwards at the switch????

[Gary S.]

Re: 1972 Corvette with Vacuum leak at the headlight switch

If this is a duplicate, ignore it. My first reply vanished, it seems.

Try this

http://www.corvette-101.com/vacuum.htm

And this

https://www.youtube.com/watch?v=_pLFkwZ2We8

[Christopher R.]

Re: 1972 Corvette with Vacuum leak at the headlight switch

thanks, I printed that and will watch the video tonight. This next question may sound crazy, but if you cannot get a good seal around a fitting even after cutting the hose to get to attempt a tight seal does a small amount of adhesive aid that situation.

[Patrick H.]

Re: 1972 Corvette with Vacuum leak at the headlight switch

Sometimes I will wrap a small amount of self-adhesive tape around the port before trying to attach the hose. The tape makes the port effectively larger so it will seal.

Of course, the cause is the cheap switch, which is why originals are much nicer.

[Michael W.]

Re: 1972 Corvette with Vacuum leak at the headlight switch

Are you sure you're hearing a leak at the switch and it's not actually the sound of air flowing through the switch? If there's a serious leak elsewhere in the system, the switch will sound quite noisy.

[Alan S.]

Re: 1972 Corvette with Vacuum leak at the headlight switch

Hi Chris,
Do you have the hoses connected to the proper port?
The 71 AIM is known to be incorrect and leads to a constant hiss at the switch. (Was it corrected for the 72 AIM?)
The blue striped hose should be connected to the forward nipple on the switch as installed.
On original hoses sometimes cutting about 3/8"-1/2" off the end of the hose improves it's ability to seal.
Maybe?
Regards,
Alan

[Christopher R.]

Re: 1972 Corvette with Vacuum leak at the headlight switch

thanks I will try check those suggestions and let you know.