'68 vacuum system

[Brian W.]

Having trouble with my vacuum system. Is there a service manual available to trouble shoot this system. Thanks

[David J.]

Re: '68 vacuum system

What is the issue with your system? Headlights, wiper door, or both? Do you have access to a vacuum pump like a Mityvac or similar?

[David H.]

Re: '68 vacuum system

Having trouble with my vacuum system. Is there a service manual available to trouble shoot this system. Thanks

Brian,

Several of the larger vendors have trouble shooting guides. Below is a sample page from one vendor:

http://www.docrebuild.com/dr-r-web/TROUBLE1.HTML

Is this the kind of information you are looking for?

Dave

[Brian W.]

Re: '68 vacuum system

Here's what happens...when I first start the car the headlight doors open and then close, after that they perform normal. Now the wiper door opens and stays open and wipers don't work. The door will close when I shut off the battery kill switch.

[Gene M.]

Re: '68 vacuum system

Brian,
Using a hand held vacuum pump test each piece separate from everything else. Also check out the vacuum tank that there is no pin hole leaks. The vacuum valve off the vacuum line from the engine is a one way, check it out separately too. Also make sure all hoses fit tight on connections and no leaks. The routing of hoses is well documented. Those routings color charts are well defined as to source and routing. The 68 is very different from 69 and later. The over ride switch is functional when the knobs are pulled down. Verify that all hose routing is correct. My opinion is the 68 system is simpler to diagnose than later c3.

[Brian W.]

Re: '68 vacuum system

Thanks Gene I will try all test next week.

[Patrick H.]

Re: '68 vacuum system

Especially test the silver check valve which is usually stationed near the left side of the intake manifold, and the wiper door closing valve which is on the far right side of the wiper trough under the removable grill. I would suggest that one of those is part of the problem.

In addition, the relays that control the headlight opening as well as the wiper door opening (the ones with 3-4 vacuum lines entering them, not the big canisters) tend to leak over time. When they get bad the whole system has issues.

Doc Rebuild's guide is a good one to use.