flynhi

My wiper door opens and then closes at startup. Stays down during normal ops. Works properly with wiper switch and override switch.

Any idea as to what causes this?

dewcustom

the wiper door uses vacuum to stay closed not open and when you first start the car you do not have the vacuum to keep it closed for maybe a sec or two this could be becuase of the cam you are using if not than you mostlikely have a small vacuum leak

mrvette

OK, mine still makes a feeble attempt to open on start up, but then slams closed again after ~1/4 inch of movement....I do not have a vacuum storage tank, and the vacuum diode....one way valve....is functional...but I don't have operating headlights anymore either....

I know the problem is related to too much spring pressure in the diaphram of the vacuum relay...meaning the thing takes a lot of suck to change the state of the routing plunger in it....

so I cut mine apart and very significantly weakened the spring, and lubed up the plunger and rubber port seals with silicone gel....

put it back together with the original clamping band, and some RTV, my favorite usual stuff, and it's working fine for about 5 years now....door hardly flips at all, like I said surges for 1/4 inch and then settles down...I can live with that...vs the other more expensive less reliable options....

GENE

Robert N

I have working lights (right side slow) and the wiper door operates with the override but not from the switch. I should have a bad switch.

Now, I screwed up my timing and before getting it corrected, the wiper door would open and close when started. Once the timing was reset, wiper door functions. (That is when the switch went bad.) I am assuming the problem was related to vac advance??

Larry B.

I think it is caused by leaking vacuum relays and actuator seals. I have had cars that did that and in all cases a new relay fixed it. All of mine work perfect and the parts are all original except for a new wiper door relay which I replace because one of the plastic nipples broke off.

theandies

That is a tell tale sign of a dirty wiper door selenoid behind the tach. Take it our and clean it and it will be good as new. Here is a link on how to do it. http://www.71corvette.com/wiper.html