kjbuster1

1972 BB, A/C, pb, ps, pb. Haven't driven in rain for a while.
Everything used to be normal. This morning got caught in the rain. Turned lites on-normal. Turned wipers on low- normal ( door opens, arms move ). After a few minutes wiper door shuts on wipers trapping them partially down. Headlites stay normal. Later, turned lites off and they shut. Shut engine down in garage, gently lifted headlite door by hand and wipers retracted to park. Tried to get wipers to operate but no result for door or wipers.

Any ideas where to start looking?

Thanks.

Mashman

For the wiper door to close, then there needs to be vacuum on the control line to the relay. When there is vacuum on the control line, then the relay directs the source vacuum to the down side of the actuator, then there is no vacuum on the relay, then the relay should direct the source vacuum to the up side of the actuator.

In the wiper bay there is a vacuum safety switch, it's purpose it to stop vacuum on the control line from reaching the relay unless the wipers are parked. When the wipers are parked, and the plunger on the safety valve is pushed, the valve allows vacuum on the control line. If the plunger is not pushed, the vavle will not allow vacuum on the control line, and the wiper door should stay open.

If the wiper door is closing when the wipers are still going, then there needs to be something wrong with either the safety valve, or the relay. My guess is that the spring in the relay has given out and it's not properly directing the source vacuum to the up side of the actuator.

Alan 71

Hi k,
Here's the safety switch mash described.
When the plunger is pushed in by the lever on the wiper transmission the door can close.
When the the plunger is out the door can't close because the vacuum signal is interrupted.
I'd agree that the operation of this valve is the first thing to check.
Good Luck!
Regards,
Alan

Plunger pushed in by lever… door can close.


Plunger out …. wipers can operate until they park again and the lever pushes the plunger in which signals the wiper door relay to close the door.

0Willcox Corvette

I have to agree with both post above... Either the safety valve is not working properly or the relay is failing.

Easy to check.

69-72 Wiper Arm Vacuum Relay testing.



Headlamp/Windshield Wiper Actuator Relay testing. 68-72 for wipers.. 68-82 for headlamp.

kjbuster1

Mashman, Alan 71 and Willcox- Thanks for all the tips. The final result was a failed Wiper Door Actuator.

0Willcox Corvette

I'm glad you found the issue.. these cars will drive you nuts sometimes..

Willcox

530planeman

Just fired up my 68 after years sitting and wiper doors won't open .tested motor as per your video and its fine ,if I put vacuum direct to canister they will open .It looks as some has removed the override system under the dash and there is a solenoid with a black and brown wire and one small vacuum line on each side .one side of the solenoid has two ports ,does one need to be caped to work ?
Thanks Wes

tracdogg2

No, the one port is just a vent. It should have a foam filter on it.

530planeman

Thanks For the help back to the drawing board .
Wes

0Willcox Corvette

And remember.. 68 didn't use the wiper arm relay..

530planeman

on my 68 the vacuum relay in the pass. side fender ,when I use a hand vacuum pump. bleeds off is this normal ?

Dave J

In a word, no. Which port are you checking? The small top port should hold vacuum with NO bleed off. On the three large ports, connect to the middle port and block off the bottom port with your finger or a blocked hose. It should also hold vacuum.

530planeman

Dave J
Thanks much
This 68 wiper system is just a barrel of fun to sort out .I will get a new one and I hope that will help.
Wes

Dave J

If your relay is original to your '68, hang on to it. It may be able to be rebuilt. '68 relays are another one year only part.

530planeman

Dave J
How do I tell if my relay is original ? I believe it says AC spark plug on the side of it ?
Wes

Dave J

The top metal "can" tells the story. If yours looks like the picture below, and the relay has the "spark plug" script, it's a '68. You should have 2, one for the headlights, and one for the wiper door.