Vacuum wipers and headights trouble

[L88 crazy]

Hey!

I got a 72 Vette that has vacuum system problems. That's no surprise. First my headlights come up slowly and I hear a hissing noise. I believe it's vacuum leaking from the left front light canister, I'm not sure. Also the wiper door on my vette doesn't work right either. I haven't used the wipers for a long time because of this problem. I think it only opened and didn't close, or it closed but didn't open up. It only works one way that's all I remember. Since almost every Corvette owner has dealt with this problem, I need help with it. Thanks to all!

 

[ernie d]

Hi L88.......do you really have an L88? AWESOME motor.

First things first, you gotta find that vacuum leak. Get your self a vac gauge (mandatory for C3 owners), put on intake manifold port. Healthy system should get 17-20 inches. Then one at a time, begin disconnecting vacuum lines with motor idling, the disconnected lines that made no change to your vacuum quality are leaking. Trace em down from there.

For the lazy wiper door, try cleaning the wiper door solenoid. Here's easy instructions.

http://www.71corvette.com/wiper.html

Good luck!

Ernie
:cool

 

[jonstr]

The vacuum system on your car is actually two almost entirely separate circuits that split just off of the intake manifold. There should be a check valve that takes the single feed from the manifold and splits it into one large and one small vacuum line.

The small line is your control circuit. This tells the various relay valves (wiper door and headlight) whether the doors should be open or closed, depending on the switch positions. The larger line is your servo circuit. This is the one that actually does the work of opening and closing the doors. It goes from the check valve to the vacuum tank and then to the actuators. The two circuits are pretty much separate from each other, but note that the control circuit controls both headlines and wiper door, and the servo circuit opens/close both headlights and wiper door, so even a single leak can affect both systems.

The whole system is biased so that, when you start the car, the control circuit should build vacuum first and set the relay valves to the correct positions before the servo circuit builds enough vacuum to pop a door open.

In general, that's how the system works. The best way to look for leaks is to park a car outside your garage, then run a LONG vacuum line into the garage and hook it up to your car. Start the car outside and close the garage door. You should now be able to hear the vacuum leaks that you can't hear with your engine running. Note that I said 'leaks'. There will be more than one, almost guaranteed. This "second car" trick wouldn't work for me, so I built a little vacuum pump out of a vacuum food sealer instead. It's not quite as effective or fast, but it works.

Dr. Rebuild sells a great (and cheap) troubleshooting guide and vacuum hose routing diagrams that helped me out tremendously when I was troubleshooting my '69.

 

[bob_robert]

Great Web Site for info

Go to www.corvette-101.com for an excellant how to for trouble shooting vacuum problems.

 

[Piet]

Shameless plug for Chris' Killer Lights...

Ditch the vacuum... every vehicle I've owned with vacuum appliances, I have replaced them cause they required too much maintenance and are not that reliable.

Chris (69myway) replaced the headlight canisters on his '69

Chris wanted to eliminate the stock vacuum and upgrade to a reliable late model OEM style system. He is now offering conversion kits. The kit comes with the brackets and hardware needed to install 1993-1997 Firebird headlight actuators in place of the stock vacuum system. The conversion kit is available for $125.

Killer Lights... 'cause Vacuum Sucks!