I found the brake booster was leaking I could feel the air leak as my wife pushed the pedal) so I replaced it and the master cylinder and now the headlights won't go up. The car sat in my mom's pole barn for 18 years after my dad passed away. I got it running and the headlights worked but now they don't. I'm thinking it needs to run for a while to build up pressure but I'm not sure. Any advice will help. I checked the hoses and they seem fine.

 

Seeming fine and being fine are two different things. Get a Mityvac and test each hose individually. Then get the vacuum write-up from the Tech/Performance section in the stickys under FAQ. Use that in conjunction with the corvette101 vacuum write-up and the vacuum information from Willcox Corvette’s site and start troubleshooting.

Be advised that there are a lot of cheap Chinese replacement vacuum parts out there that aren’t worth a tinker’s damn, so buy quality replacement parts or rebuild what you can yourself. And of course, come back here and ask lots of questions!

Happy hunting!

 

theres a bypass under the dash. Make sure that isnt pulled. If they worked then suddenly dont it may just be an unpluggged hose. And yes you do have to build vacuum for a few minutes if its just idling

What year is your car

 

It's a 1981.

 

Vacuum hoses can test fine with but still leak. How? The ends gets stretched out a bit and they no longer seal at the connections most of which do not use (or need) clamps. If the hose tests fine--it should hold vacuum indefinitely--like days I suggest you trim the ends about an inch. Many are long enough to do this--once--but others aren't.

When replacement hoses are needed know that those sold at basic stores like Autozone or Advance will NOT work. Presuming they're still available I suggest complete hose kits from Doc Rebuild--they come with everything you need--hoses, fittings, clamps (in the few places used) and instructions. They are the correctinside and outside diameter (outside diameter really matters at the vacuum relays) and are striped just like the originals.

The BEST engine performance thing I did to my low-mileage, highly original and reasonably maintained '79 was to replace ALL of the vacuum hoses! I suspect you should do the same. Again I suggest Doc Rebuild for the hose kits. You'll need headlamps, emissions, pcv/vapor recovery and cruise (if equipped). The HVAC vacuum hoses use a different connection method and tube material and are extremely long-lived. This will take care of nearly all of the vacuum hoses in the car. Do not forget the little rubber hose at the vacuum modulator valve on the automatic transmission.

I'm not trying to put the cart before the horse when saying you replace vacuum hoses. Actually for the age and length of time it has sat I suggest you replace EVERY rubber hose and belt in the car! There are a LOT of them. If anything like mine they WILL all start leaking/break with only light use of the car.