C3 Headlamp / Wiper Door Problems

[Zachary K.]

1970 350/350 In need of a little help or advice. On initial start up headlamp and wiper doors open and close. As long as there is vacuum in the reserve tank this will not happen. I have been wondering if the acuators are not adjusted properly will this cause a vacuum leak to empty the tank. Running I have 14 - 15 inches of vacuum and when shut off with vacuum gauge in line i get a very slow drop which will empty the system in anywhere from 10 to 20 minutes. If the actuators need adjustment, a good starting point would be ?? turns from the start of the threads? Also, the wiper acutuator ?? turns from the start of the threads and of course the inter- link / nut which has left hand threads. I had some help from a fellow NCRS friend but over the past few days I haven't been able to reach him. Filter is new and not leaking also the check valve is new and not leaking. Thanks for any help and advice.

[Alan S.]

Re: C3 Headlamp / Wiper Door Problems

Hi Zach,
I think what you're seeing happens quite a bit.
I believe that on start-up the actuator side of the vacuum system (large hoses) is is attaining the necessary amount of vacuum before the control side of the system (small hoses). Have you been able to check that the relays are not leaking and allowing that to happen?
These symptoms have been talked about quite a bit over the years? Have you tried doing a search in the archives for "winking lights and wipers', or variations of those words?
Good Luck!
Regards,
Alan

[Zachary K.]

Re: C3 Headlamp / Wiper Door Problems

Yes I used the search, and although I didn't use your term "winking" which drew a blank, the many variations that I used also came up empty. I'm still trying, thanks for your suggestion.

[Alan S.]

Re: C3 Headlamp / Wiper Door Problems

Hi Zach,
Do you have a vacuum pump with a gauge like a Mity-Vac which will allow you isolate the various components and begin to test their 'open' and 'close' sides for slow leaks?
Having a trouble shooting guide like the one from Dr. R which contains info on testing each component is a big help too.
Some people have had sucess just cutting 1/3" to 1/2" off the end of each hose which will give new seal sufaces.
Again, Good Luck!
Regards,
Alan

[Bill C.]

Re: C3 Headlamp / Wiper Door Problems

check all the signal hoses to be sure there are no obstructions.

I had a hose get pinched under the dash one time.

[Zachary K.]

Re: C3 Headlamp / Wiper Door Problems

Yes I have, and have gone over the system completely, no idea how many hours invested. Hoses are fine vac filter is new as is check valve, relays have checked as per doc rebuilds check sheet as was the interlock and actuators themselves. Went as far as removing each hose and checking individually. My last resort was actuators and the rods they are moved by. Not sure if someone had fooled with them and can't find anywhere the correct way to check that if they were installed incorrectly.

On the previous thread, just a note. I searched the current board and forgot about the archive boards, which did show dancing headlight posts. Thanks for that term as it wasn't one of my thoughts last night a 1:00AM
Those posts although helpful posted things I've been through already. Looks like I have a tough one here. Trying to PV this car and just can't get past this problem. Again, thanks for your help and suggestions.

[Jim T.]

Re: C3 Headlamp / Wiper Door Problems

Zachary I believe it is going to take new parts to solve your problem. My 70 has a headlight up down feature now that was not there 40 years ago when I bought it. When I get on WOT or close to it my right headlight will come up and go back down when I come off the gas pedal.
I don't drive much at night, so I just disconnected vacuum to the headlights. To raise the headlights if I had to, it is so easy to lift them into position and it is about as easy to lower them when you know where to place your finger to bring them down.
Dr. Rebuild might be a place for you to check out for information on working on the vacuum system.
I have new relays I purchased over 20 years ago, but continue to keep my 70 original.

[Paul O.]

Re: C3 Headlamp / Wiper Door Problems

Zachary sounds like the leak may be at the control side source. The reason I say that is both your headlight and wiper doors move. Start at the engine check valve and move to the inside of the car at the override switches where the feed hose splits to the headlight and wiper override.

Usually if the leak is after that only one system will wink not always but most often. You can use a vacuum clamp pliers to isolate each system headlight/wiper this could make the troubleshooting go faster.

Also if you have another car you could park that car outside of your garage and use it as your vacuum score. Buy enough hose to to to get from the car to the Vette connect to a vacuum port close the garage door and work on your system. If the other car is not loud you also may be able to hear the leak.

Paul 18046

[Edward J.]

Re: C3 Headlamp / Wiper Door Problems

Zack, I Had a simialiar problem with my wiper door doing the same thing on start-up the wiper door would cycle up and down on start, The problem ended up being the vaccum switch that the pass. side wiper arm rests on, The button on top was broken and was totaly missing as was the protective boot. amazed the door still operated, The valve was stuck internally between the ports causing my problem.

[Roger O.]

Re: C3 Headlamp / Wiper Door Problems

When the system leaks down completely all the relays are sitting in the UP position. When the engine is started the vacuum builds and if everything works right the relay will be moved into the DOWN position before the actuators can react and the doors stay down.
The spring in the relays are pretty stiff so if the small hose side of the system has the tiniest leak the relay will tell the doors to go up before the vacuum builds enough to reverse the action.
Someone mentioned the vacuum switch under the wiper arm,this is a common place for a leak. If you have a min. try this, engine running , wiper switch to off ,(wiper door is down) pinch the small red hose going to the vac switch under the wiper arm and hold for 15 seconds. If the wiper door pops up you most likely have a leak in the vac switch.( could be in the relay or hoses but most likely the switch)

I think many of these cars are developing this up and down and in some case it has to do wiper doors that move faster than original.