1968 corvette wiper door troubleshooting

Get a vacuum gauge and check the vacuum to the module that controls the door movement. I had a 69 and played around with these vacuum systems. Didn't really have a problem with them but did need to get a new check valve. That was if you do not get enough vacuum. There is a cannister that 'stores' vacuum so you do not get your headlights closing when you step on the gas and drop vacuum. Likely applies when you shut the engine off too. You possibly need a new check valve so there is enough vacuum to close the door after the engine is off. I believe the check valve is located in line with the vacuum line where it goes into the base of the carb.

Thanks, I will give the check valve a shot. Could that also cause the door to open when I start the car? I understand how it can keep the door from closing, What about the safety over ride solenoid on the back of the tack? Ken

That may be a solenoid that guarantees there is vacuum to the open side when the wipers are turned on. But my guess is that there would be a switch that would not allow the wipers to come on unless the door was sensed to be open. I sold my car years ago and I am going by memory. There is also a rubber seal on the actuator shaft that can be replaced. When that seal wears out vacuum leaks for the action in that direction. If that direction is to close the door, that could explain why the door doesn't always stay closed. The closing action is weak due to a vacuum leak at the seal where the shaft slides.

If when the engine starts, you get weak vacuum on either side of the actuator, it could move the actuator to open the door since one side has less vacuum due to a shaft seal leak. When vacuum builds, the effect of the valving take over and the actuator takes its proper position which is closed. Check the shaft seal and replace the seal if worn.

Thanks, I will check out the seal this morning. Ken