I pulled the 427 motor out of my car for rebuilding, and while the engine was out I installed a new vacuum hose kit. Now that I have the car running and driving I'm having a problem when starting the car the wiper door slowly opens and slowly closes.I have all the new hoses in their correct location as I have gone over the diagram time an time again. Headlights open and close fine. Wiper door stays closed when engine is off.Where do I look ?
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Re: 1969 corvette vacuum system
There are several vacuum troubleshooting booklets available from several vendors. I have never used any of them, but others on this board recommend the one from Dr Rebuild. YMMV Where did you source your replacement hoses?
If you intend to trouble shoot the C3 vacuum system you are best off getting the resource material and exploring for your problems (note the plural. There are almost always more than one) yourself. Each car is unique and will present unique issues and you have to find them yourself. Throwing parts at a vacuum problem will become verry frustrating.
All that said you must understand the basics of the systems. There are really two systems -- the control circuit (small hoses) and the power circuit (big hoses). The clever engineers who designed the system (stop cursing them) designed it so that the control system, being smaller in volume (remember small hoses) than the power circuit will build up vacuum first and thus the items operated will remain in their previous positions as vacuum builds.
If you understand the above then you know you have a leak in the control circuit for the wiper door. Now go find it. Don't rule out the vacuum control valve for the wiper door. The diaphragm may be leaking, but your new hoses may not fit tightly either.
I like to T' a vacuum gauge into the vacuum system and begin to pinch off various parts of the system until I see the vacuum gauge begin to notch up. Following that circuit all the way will show the leak. Obviously this is far easier if one has a source of vacuum other than the engine.
Good luck. Also check out the last thread listed below under 'similar threads'. There are other and better threads on this board, including entire troubleshooting directions. Carry on.Terry -
Re: 1969 corvette vacuum system
Gary, I just went through the same troubleshooting of the wiper door action. I found that the four port rubber connector at the wiper door override switch had split causing a leak on the control side. I wasn't able to find a replacement after searching many vendors. Finally found a used one. The seller has another one and I can send you his contact info if you need it.
As Terry stated the are many troubleshooting guides available. I found a very helpful schematic diagram for my late 69 at willcoxcorvette.com. At their site search "1969 vacuum" then click "Tech Pictures" in the two results. The first of the four diagrams was for my car. The third diagram is for the "early" 69.
Good luck!
MikeComment
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Re: 1969 corvette vacuum system
Hi Gary,
I agree that there are some good trouble shooting posts on this board.
Jack Humphrey has written some of them. Search his name and/or winking headlights/dancing wiper door. (That last one is how he describes your situation).
Regards,
Alan
Searching just 'winking' brings up a good list of helpful threads and posts.Last edited by Alan S.; April 21, 2014, 02:10 PM.71 Coupe, 350/270, 4 speed
Mason Dixon Chapter
Chapter Top Flight October 2011Comment
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Re: 1969 corvette vacuum system
Michael, Thanks for taking time to respond. Yes I would like your contact on the override switch. G HobbsComment
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Re: 1969 corvette vacuum system
Gary, I just sent you a PM with his info.
MikeComment
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