Had to put the vette into service this week and found I have no vacuum for headlight doors or wipers. All else appears fine, the car is running ok. I am away from my manuals and was hoping somebody may have an idea. All vac lines appear to be ok, could not find anything disconnected. Help please!

 

No vacuum with the engine running? Can you hear a vacuum leak?

 

Can not hear any leaks

 

Hi 156,
What sort of 'service' was performed? What area of the car was the tech working on?
Did the over-ride switches under the steering column get pulled by mistake?
Regards,
Alan

 

Where are you checking the vacuum? I have a '74 and I don't know what year you have so if your tank is different this may not be quite the same. The small vacuum hose that comes out of the firewall and goes to the control valves should have vacuum with the headlights off and no vacuum with the headlights on. I would check at the input line to the vacuum tank next. If you have it there I would reconnect it to the tank and check the tank by plugging one hose that goes to the control valve and using the other hose to make sure the tank is holding vacuum. If that's OK then I would connect one side and test it while the other fitting from the tank is still plugged. . The control unit should have vacuum at the red striped hose that goes to the top fitting on the actuator to LOWER the headlight (in other words with the headlights off) and vacuum at the green striped hose that connects to the bottom fitting on the actuator to RAISE the headlight (headlights on). If you have the vacuum at both of those fittings at the proper time attach the actuator and see if that side works. If that side works with the other side still plugged at the tank fitting or hose, then you can leave it connected and go through the same process on the other side. By the time you do all those checks, you should know where the problem is.

Good Luck.

 

Thanks for the responses. This is on my 72. The over-ride switch did nothing by the way. I finished my front end rebuild a few months back, but lights and wipers have worked ok since then. I will start the search for the culprit.

 

Issue Found! After searching the vac system, I found the problem at the stainless tubing where it connects to the plastic tubing. This was in a bundle under the drivers side hood latch. Very hard to see unless you seperate all the wires and tubing. Thanks guys for the help!!!

 

Glad you found it.

 

The internal combustion engine is just an "air pump". And, as such, there must be a 'negative pressure' [vacuum] on the input side of that pump (intake manifold) when it is running.

If you are measuring "0" vacuum on the engine, either there is a big leak before the measurement point...or the gauge is stuck on "0"...or both.