Home page
SPONSOR AD SPONSOR AD

Topic: wiper door cycles open-close

in Forum: C3 Body


wiper door cycles open-close

Posted: 8/13/04 4:22am Message 1 of 9
Former Member
Send PM
Cincinnati, OH - USA
Joined: 1/25/2004
Posts: 39
Vette(s): 70 Coupe 350/350 4 spd
I have a 1970 350/350.
Each time I start the car the wiper door opens and closes. Only once, but every time.

Also, if I really put my foot into the motor, the wiper door will open and close.

Why? Is it normal? Does every car do this? If not, what needs to be done to fix this?

Thanks
Mickey


SPONSOR AD:: (Our Sponsors help support C3VR)

wiper door cycles open-close

Posted: 8/13/04 4:51am Message 2 of 9
Profile Pic
Former Member
Send PM
Frederick, MD - USA
Joined: 9/8/2003
Posts: 3398
Vette(s): 1969 convertible L71 427/435 4-speed black interior
My '69 L71 does the same thing, and the headlights usually open and close as well.

It's not normal. There is likely a vacuum leak in a relay that controls this system. When vacuum is built back up the access door (and headlights on my car) close.

On my car, they stay closed, they don't open when I get into the throttle.

I haven't been able to take the time to find the problem on my car, but in my case at least, it will be in a part where vacuum is shared by the headlights and wiper door. Yours sounds like a vacuum relay that affects just the wiper door.

|UPDATED|8/13/2004 4:51:26 AM (AZT)|/UPDATED|



wiper door cycles open-close

Posted: 8/13/04 9:53am Message 3 of 9
Former Member
Send PM
Wayne, NJ - USA
Joined: 5/31/2002
Posts: 973
Vette(s): White 1975 L48 Stingray 129,000 Miles, daily driver.
My neighbor's 75 w/a ZZ-502 will pop the headlights up when he punches the throttle...he says the system is leak free, but the motor does not produce enough vacuum. I'm no expert but if you're running a very hi-perf motor that might have an affect. ?

Scot |wavey|


wiper door cycles open-close

Posted: 8/13/04 10:23am Message 4 of 9
Profile Pic
Lifetime MemberLifetime Member
Send PM
Hot Springs, AR - USA
Joined: 4/24/2004
Posts: 3236
Vette(s): 69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans
 Paragon75Ray said: I'm no expert but if you're running a very hi-perf motor that might have an affect. ?

Scot |wavey|
 


yeah thats why you make sure you have the vac canister..

sometimes even this isnt enough


wiper door cycles open-close

Posted: 8/13/04 10:42am Message 5 of 9
Profile Pic
Former Member
Send PM
Frederick, MD - USA
Joined: 9/8/2003
Posts: 3398
Vette(s): 1969 convertible L71 427/435 4-speed black interior
Maybe having a high performance motor does have something to do with this problem. My 427/435 has a more radical cam installed ('67 L88 grind), and the engine has very little vacuum. It definitely takes a strong leg to push on the "power" brakes to bring the car down. There could certainly be a leak somewhere in the headlight/windshield wiper door system, but maybe the low engine vacuum is related. I don't even try to say I'm well versed enough in these matters to know.

I'm interested in anyone else's ideas on this.


wiper door cycles open-close

Posted: 8/13/04 10:54am Message 6 of 9
Former Member
Send PM
KERNERSVILLE, NC - USA
Joined: 1/13/2004
Posts: 1355
Vette(s): 1968 L-71 convertible
Bruce, I'm going with your first response, a weak or leaking relay. I would think that with the high perf engines, you would get a sluggish response on wiper and headlight doors, but not an erratic operation.


wiper door cycles open-close

Posted: 8/13/04 11:04am Message 7 of 9
Profile Pic
Former Member
Send PM
Frederick, MD - USA
Joined: 9/8/2003
Posts: 3398
Vette(s): 1969 convertible L71 427/435 4-speed black interior
A weak or leaking relay does make the most sense. I just don't have enough knowledge about the system to do more than make guesses. Makes you wish Chevrolet never installed the windshield wiper door and made the headlight rotating system electrical. Then again...we would be suffering with a whole different set of problems. Such is life.


wiper door cycles open-close

Posted: 8/13/04 11:20am Message 8 of 9
Profile Pic
Lifetime MemberLifetime Member
Send PM
Hot Springs, AR - USA
Joined: 4/24/2004
Posts: 3236
Vette(s): 69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans
 Gunslinger said: Then again...we would be suffering with a whole different set of problems. Such is life. 


well starting at one end and checking every vaccum component for leak with your hand pump is the test method.. but you will very likely have vac problems with such a beastly engine..

with my fairly radical cam small block vette... I checked and rechecked for leaks.. had a canister.. yet when i was really getting on it the accessories opened.

i didnt really care too much.. but eventually I connected the vaccum relays backwards and left the override valves pulled out.. this made them stay closed..

but there was a slight hissing inside the car.. (radio covered it up)

what you can do is add a shut off valve to the system.. run your accessory line into the car first and put a brass shutoff valve under the dash.. if it rains or your driving at night turn it on..

odds are you wont be driving that hard at night or in the rain and the vac wont be a problem..

also.. you may want to connected a vaccum gauge inside the car temporarily to test with.. this way you can see if the component fails at 7 psi but not 9 psi..

find out where the vac system goes haywire.. then see what component doesnt behave correctly at that vac.


wiper door cycles open-close

Posted: 8/14/04 8:34am Message 9 of 9
Profile Pic
Lifetime MemberLifetime Member
Moderator
Send PM
CUYAHOGA FALLS, OH - USA
Joined: 12/2/2003
Posts: 6424
Vette(s): 1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!
It can be much easier. Just get a one way vacuum check valve. Connect it in the supply line from the engine. When engine vacuum drops, you keep vacuum, unless you have a leak. If the check valve is not enough, you can add a T after the check valve, and install a vacuum cannister for reserve supply. Many cars do this from the factory.


in Forum: C3 Body


SPONSOR AD: (Our Sponsors help support C3VR)