Vacuum gurus needed
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Vacuum gurus needed
71 BB no air.
I've read every post on vacuum problems and am getting this headache narrowed down. Wiper door will neither open nor close. This happened all at once so I'm sure everything is hooked up properly. If I manually open door, wipers work normally on both low and high. Using info from this site I've confirmed that filter, checkvalve, tank, overides, actuator are all good.
Using info from Willcox, I performed a test on the "Wiper arm vacuum relay" (under pass side wiper with white button) it says "when car running should get vacuum to middle nipple" I do NOT get any vacuum here. It says about tach solenoid: "function of tach solenoid is to stop flow of vacuum from reaching wiper arm relay valve" so I'm assuming tach solenoid is working?? Any insight here would be greatly appreciated.
I've read every post on vacuum problems and am getting this headache narrowed down. Wiper door will neither open nor close. This happened all at once so I'm sure everything is hooked up properly. If I manually open door, wipers work normally on both low and high. Using info from this site I've confirmed that filter, checkvalve, tank, overides, actuator are all good.
Using info from Willcox, I performed a test on the "Wiper arm vacuum relay" (under pass side wiper with white button) it says "when car running should get vacuum to middle nipple" I do NOT get any vacuum here. It says about tach solenoid: "function of tach solenoid is to stop flow of vacuum from reaching wiper arm relay valve" so I'm assuming tach solenoid is working?? Any insight here would be greatly appreciated.
Team Owner
Joined: Sep 2006
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From: Westminster Maryland
Hi SS,
It seems to me it has to be the solenoid valve switch, since this solenoid is energized by the wiper switch and then sends the vacuum signal to the wiper relay valve to open the door.
Regards,
Alan
It seems to me it has to be the solenoid valve switch, since this solenoid is energized by the wiper switch and then sends the vacuum signal to the wiper relay valve to open the door.
Regards,
Alan
Former Vendor
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
It says about tach solenoid: "function of tach solenoid is to stop flow of vacuum from reaching wiper arm relay valve" so I'm assuming tach solenoid is working?? Any insight here would be greatly appreciated.
The function of the solenoid is to stop vacuum on this hose when the wipers are turned on.
So when the car is running you should have vacuum on the red hose between the over-ride switch and the wiper arm switch. You would also then have vacuum between the over-ride switch and the tach solenoid on the lt blue striped hose.
Willcox
The function of the solenoid is to stop vacuum on this hose when the wipers are turned on.
So when the car is running you should have vacuum on the red hose between the over-ride switch and the wiper arm switch. You would also then have vacuum between the over-ride switch and the tach solenoid on the lt blue striped hose.
Willcox
Team Owner
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From: Crossville TN
Have you measured the amount of vacuum coming off the manifold and at one of the bypass valves [under the steering wheel]? I'd guess that there is a vacuum hose loose under the dash somewhere...either at the solenoid/switch on the tach or at the headlight switch.
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It says about tach solenoid: "function of tach solenoid is to stop flow of vacuum from reaching wiper arm relay valve" so I'm assuming tach solenoid is working?? Any insight here would be greatly appreciated.
The function of the solenoid is to stop vacuum on this hose when the wipers are turned on.
So when the car is running you should have vacuum on the red hose between the over-ride switch and the wiper arm switch. You would also then have vacuum between the over-ride switch and the tach solenoid on the lt blue striped hose.
Willcox
The function of the solenoid is to stop vacuum on this hose when the wipers are turned on.
So when the car is running you should have vacuum on the red hose between the over-ride switch and the wiper arm switch. You would also then have vacuum between the over-ride switch and the tach solenoid on the lt blue striped hose.
Willcox
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Well, now headlights won't come up either. Does tach solenoid have anything to do with headlights?? If I apply vacuum to smaller hose coming off check valve that goes thru firewall to "T" by solenoid, it holds pressure. I'm really confused now...
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That's good. Now if I can figure out where vacuum is dissappearing... Willcox said "when car is running should have vacuum on red hose between overide and wiper arm switch" I removed molded double hose connector from wiper overide and get no vacuum on either hose. Now what?
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Le Mans Master
Joined: Jul 2006
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From: charlotte north carolina
check the vacuum filter for cracks, especially if it's a plastic after market style. mine split and suddenly lost wiper door movement. took me a while to see the small split where the two halves are glued together.
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I get 20.5 of vacuum both before and after filter, so I assume it's OK.
Race Director
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From: Dayton, Ohio
Have you tried pulling the small hose off at the wiper relay ? also at the headlight relay ?
Pulling this small hose off should "tell" the relay to make the headlights or the wiper door to go UP , "if" there is vacuum present on the large hose (yellow stripped) at the relay.
Pulling this small hose off should "tell" the relay to make the headlights or the wiper door to go UP , "if" there is vacuum present on the large hose (yellow stripped) at the relay.
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Have you tried pulling the small hose off at the wiper relay ? also at the headlight relay ?
Pulling this small hose off should "tell" the relay to make the headlights or the wiper door to go UP , "if" there is vacuum present on the large hose (yellow stripped) at the relay.
Pulling this small hose off should "tell" the relay to make the headlights or the wiper door to go UP , "if" there is vacuum present on the large hose (yellow stripped) at the relay.
Former Vendor
Joined: Aug 2006
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
The wiper relay and headlamp relay are actually the same part. Yes the one for the wipers is located on the inner fender and the one between the headlamps is for the headlamp actuators.
The relay controls the function. They tell the actuators to either stay closed or to pull open. On headlamps or on the wiper system.. to stay closed you must have vacuum on the small hose running to the top of the relay.
Willcox
The relay controls the function. They tell the actuators to either stay closed or to pull open. On headlamps or on the wiper system.. to stay closed you must have vacuum on the small hose running to the top of the relay.
Willcox
Last edited by Willcox Corvette; Jan 28, 2010 at 09:16 AM.
Safety Car
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From: Wichita KS
You might check the hose connections on the vacuum tank. There is one way back under the fender. You need a flashlight to see it.
Also, one of the nipples on the tank is smaller than the others so make sure you have the correct hose on it. It should have the large hose from the check valve on it. The opening on that hose is smaller than the feeders for the wipers and the headlights.
cc
Also, one of the nipples on the tank is smaller than the others so make sure you have the correct hose on it. It should have the large hose from the check valve on it. The opening on that hose is smaller than the feeders for the wipers and the headlights.
cc
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OK, I found I have NO vacuum on the middle (yellow) hose on wiper relay mounted to lower pass side fender. Remember that headlights stopped popping up also. No hoses can be routed wrong because everything worked fine a month ago and I haven't changed a thing. Any suggestions as what to do next?
Safety Car
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From: Wichita KS
Start at the intake manifold and work your way out checking the connections all the way. Be especially mindful of connections that would affect the entire system and only worry about the large hoses. The small ones should not do this type of thing.
I am still suspicious of the hose connections on your reservoir. There is also a "T" connector on the hose feeding the right headlight. One end goes to the reservoir while the other end goes to the wiper door metal cross tube.
cc
I am still suspicious of the hose connections on your reservoir. There is also a "T" connector on the hose feeding the right headlight. One end goes to the reservoir while the other end goes to the wiper door metal cross tube.
cc
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Start at the intake manifold and work your way out checking the connections all the way. Be especially mindful of connections that would affect the entire system and only worry about the large hoses. The small ones should not do this type of thing.
I am still suspicious of the hose connections on your reservoir. There is also a "T" connector on the hose feeding the right headlight. One end goes to the reservoir while the other end goes to the wiper door metal cross tube.
cc
I am still suspicious of the hose connections on your reservoir. There is also a "T" connector on the hose feeding the right headlight. One end goes to the reservoir while the other end goes to the wiper door metal cross tube.
cc
Safety Car
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From: Wichita KS
I'll certainly check. In the meantime I found another strange thing. I get 20.5 of vacuum coming out of large hose out of check valve and only 3 hg out of small hose. If I replace checkvalve with a "T", headlights will again open (slowly) but wiper door still will not operate.
The small hoses, AKA the control system, do not require as much vacuum because they are only moving light weight valves.
All the work of opening and closing the headlight and wiper doors is being done on the primary system which is why it has a reservoir and larger hoses to carry more vacuum.
The vacuum tank, or reservoir, is key to the headlight system. Without reserve vacuum they won't work or at best won't work very well.
In a tight system, if you forget to turn off the lights before you shut the engine off the reservoir will handle closing the headlight doors when you push the switch in.
cc
Last edited by CCrane65; Jan 25, 2010 at 06:36 PM.
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You definitely have a major leak in the primary, aka servo, system.
The small hoses, AKA the control system, do not require as much vacuum because they are only moving light weight valves.
All the work of opening and closing the headlight and wiper doors is being done on the primary system which is why it has a reservoir and larger hoses to carry more vacuum.
The vacuum tank, or reservoir, is key to the headlight system. Without reserve vacuum they won't work or at best won't work very well.
In a tight system, if you forget to turn off the lights before you shut the engine off the reservoir will handle closing the headlight doors when you push the switch in.
cc
The small hoses, AKA the control system, do not require as much vacuum because they are only moving light weight valves.
All the work of opening and closing the headlight and wiper doors is being done on the primary system which is why it has a reservoir and larger hoses to carry more vacuum.
The vacuum tank, or reservoir, is key to the headlight system. Without reserve vacuum they won't work or at best won't work very well.
In a tight system, if you forget to turn off the lights before you shut the engine off the reservoir will handle closing the headlight doors when you push the switch in.
cc
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Well, I've checked all the large hoses under the hood and they hold vacuum. I'm now thinking I have a major leak on the wiper side, causing the headlights to have little vacuum. Wiper door never budges at all. I need to get an outside source of vacuum so I can also hear something. Maybe a little electric vac pump.