Windshield Door Vacuum Problem

[Mark H.]

Good morning,

I was hoping someone could help me trouble shoot a probem I am having with my 1970 coupe door. I replaced all the vacuum hoses with the molded kit from Dr. Rebuild. After replacing all hoses my windshield wiper door is not closing. I have observed the following while trouble shooting:

1. If I put my finger over the wiper switch vent line and plug the hole the door closes, but as soon as I take my finger off the vent line the door opens;

2. When I shut the engine down I hear a lot of vacuum escaping form an area behind the distributor cap

3. Head lights operate the way they were intended.

I was hoping that someone could help me troublesoot where I have a problem.



I was wondering if there is a way to test the operation of the wiper relay valvue to determime is function properly?

Thanks for your help and assistance.

Mark

[Roger O.]

Re: Windshield Door Vacuum Problem

Sounds like the wiper door safety switch (valve under pass. arm)is leaking or not adjusted correctly. When the wipers are turned to off the passenger side wiper arm must come down all the way and also push the plunger in the safety switch to the bottom of its travel to allow vacuum to pass through to the relay.

Vacuum on the small hose at the wiper door relay tells the door to go DOWN.
No vacuum on the same small hose tells the door to go UP.

[Alan S.]

Re: Windshield Door Vacuum Problem

Hi Mark,
While I can't offer any help I'd like to suggest you think about buying the Trouble Shooting Guide from Dr. Rebuild. The information the guide contains allows you to test each vacuum system component individually. It's only a few $ and I found it very useful.
Good Luck!
Regards,
Alan

[Mark H.]

Re: Windshield Door Vacuum Problem

Thanks Alan,

I bought a Troubleshooting guide from COrvette Central. Do you know if the one from Dr. Rebuild is more detailed for troubleshooting?

Mark

[Edward J.]

Re: Windshield Door Vacuum Problem

Mark, I had a problem with the vaccum switch that roger is talkng about, there plastic and will break easily, on my car the button on the top broke off and left the switch stuck betweeen the ports, this caused my door to cycle up and down when starting the car.

[Mark H.]

Re: Windshield Door Vacuum Problem

Thanks Ed,

I have replaced the plastic saftey switch that bumps up against the wiper arm....like you said they are plactic and I might have gotten a defective switch. I ordered it through Corvette Central...thinking about getting a new switch again from Dr. Rebuild.

Mark

[Edward J.]

Re: Windshield Door Vacuum Problem

Mark this would'nt be the first time I've heard this, the board has discussed this before and the concenus was to buy two, because of the problems.

Also recheck the vaccum hoses to make sure there routed correctly on thay switch.

[Mark H.]

Re: Windshield Door Vacuum Problem

Thanks Roger,

WHen you say adjusting the saftey switch, I assuming you mean positioning the switch via angling the bolts that secure it. If so how do I know when it is properly seated?

Thanks

[Jack H.]

Re: Windshield Door Vacuum Problem

WHen you say adjusting the saftey switch, I assuming you mean positioning the switch via angling the bolts that secure it. If so how do I know when it is properly seated?

No, I believe he meant just what he said...adjusting it.

Look at the switch and you'll see the holes for mounting screws are slightly enlongated. That allows you to make minor switch position changes with respect to the rest position of the wiper arm against the switch before you finally tighten the switch down.

This adjustment process is called out in your copy of the Chassis Service Manual where the operation of the wiper door is documented.

[Roger O.]

Re: Windshield Door Vacuum Problem

Thanks Roger,

WHen you say adjusting the saftey switch, I assuming you mean positioning the switch via angling the bolts that secure it. If so how do I know when it is properly seated?

Thanks

Mark,
Just as Jack said and try to make sure the plunger on the top of the switch is resting squarely under the wiper arm or the top can break off. The 2 bolts will give you some leeway in respect to squareness also.
Also make sure the passenger arm is fully down in the park position.

[Mark H.]

Re: Windshield Door Vacuum Problem

Thanks to all.

After some adjusting of the windshield door swithch, the wiper door is closing again as it was intended!

Thanks again for your assistance.

Mark

[Alan S.]

Re: Windshield Door Vacuum Problem

Hi Mark,
The Dr. Rebuild info is a bit different than the others. Since you've had success with your problem you should buy it to insure you'll NEVER need it!!!!
Regards,
Alan