corvette427

Hey Gang - can someone tell me what I should be looking at replacing? I have a 72 and since I got her, the wiper door always had a little mind of her own - opening and closing erratically while I drove. It always worked correctly when I flipped on the wiper switch and still does currently. The problem while driving has gotten worse, however, as now, the wiper door will open while I'm warming up the car and will stay that way throughout the ride, or sometimes, it will close back up while I'm driving - sometimes staying shut, other times opening back up a few minutes later.

I know there is an actuator for the wiper door that can be replaced, but while looking for one, I also came across a wiper door vaccuum actuator relay. Based on my description above, do I need to replace the actuator:

http://www.ecklers.com/product.asp?p...dept%5Fid=1318

or this relay switch?

http://www.ecklers.com/product.asp?p...dept%5Fid=1477

By the way, if it makes any difference, my headlights work fine.

Thanks in advance for your help!!

c69vete

I have a similar condition now. As I have recently replaced the relay I am fairly sure it is the actuator. Mine will open when I start the car and then close, and will open under hard acceleration and close when I let up. MIne will work when I use the switch or the override control. If you have a vacuum guage try hooking up to one side of the actuator while the car is running. If you are hooked up to the pull open side when the wiper door is shut, there should be no vacuum reading on the guage. If there is it means that there is a leak on the internal seal of the actuator. a new actuator from Ecklers is about 104.00 depending on the year. If you replace the relay, it can be had from GMparts direct for about 45.00. Good Luck

Gage

i just went through this. You more than likely need this part.


http://www.ecklers.com/product.asp?p...dept%5Fid=1326

yukon988

My first guess would be the relay. The smaller line going to it is the control. If vacuum is supplied in the small line, the relay should send vacuum to the actuator to close the door. If there is no vacuum, it should open the door. The actuator does not need vacuum to hold the door either open or closed, it only needs vacuum to move the door.

If the wiper arm control valve (mentioned by Gage) is partially clogged or not adjusted right, I could see this being the problem also. Make sure when the wiper is down, it is pushing the top of that valve all the way down. If it is not fully down, it could shut off vacuum to the control end of the relay I talked about above and cause the door to open.

Another possibility is the solenoid behind the tach under the dash. If it is partially clogged, it could do that also.

If the door opens while idling, here is what you can do:

1. take off the control line on the relay (the relay is attached to the wheel well) and see if there is vacuum there (you can tell just by putting a finger over the hose). If yes -- the relay is bad because vacuum should make it switch to close the door. If no, put that hose back on and go to step 2:

2. There is a small diameter solid line that runs the width of the firewall (there is actually one small one and one larger one). Remove the vacuum hose that connects to this small solid line and see if there is vacuum on the solid line. If yes -- go to step 3. If no, go to step 4.

3. Plug the hose back in. Remove the grill between the hood and the wiper door. You should see the wiper arm control valve being pushed closed by the passenger side wiper arm. If it looks like it is not all the way depressed -- try pushing it and seeing if that makes the door close. If so, you need to adjust your wiper arm to fully depress it when the wipers are off. If depressing the end of the valve doesn't do anything -- it probably needs replaced. By the way, what I am talking about depressing is the big white button on the end in the picture in Gage's link.

4. OK -- so you don't have any vacuum in the solid line. Put the hose back on and go over to the driver's side. Unplug the hose going into the solid line there. Still no vacuum? Then the solenoid behind the tach must be getting plugged up (this is a common problem, though one of many for these systems). If you do have vacuum on this end then there is something wrong with the solid tube -- either a hole or plugged up.

Don't be surprised if you have multiple problems. To get my wiper door to work I had to:

buy an actuator (there was none on there when I bought it)
replace the relay
replace the wiper arm control valve
unclog the small solid vacuum line
rebuild the solenoid (you can't buy new ones)

By the way, the fact that your headlights work fine tells me that the problem is somewhere from the solenoid to the relay because there is a "T" in the vacuum line just before the solenoid and one side controls the headlights while the other side controls the wiper door.

Oh, and one more thing I just thought of -- if the manual override siwtch has a vacuum leak, this might cause the problem also. This is the one that you pull down under the steering column to manually open the door.

wombvette

Before you do anything else check the check valve at the rear of the manifold. If it does not work properly the vaccum is not steady to the system. Thats the pot metal one with one hose in and two out.

IDOXLR8

Thinking your problem over it sounds like a break in a ground somewhere. I would give the whole system a real good check over for opens in the grounding curcuit and opens on one of the many connections. AL.

Easy Mike

corvette427

Thanks for all the great advice guys, I appreciate it!!

Now the next challenge becomes finding the time to get under the hood and check all this out!

Tampa Jerry

No disrespect, but the lights and wiper door system(s) do not operate on an electrical ground. They operate on vacuum only. When energized, the lights come on and the wiper motor works. Different systems. Please check your vacuum lines. I had the same problem of the wiper door and headlights opening and closing as the engine speed changed. After going crazy replacing the actuator(s), I found that rodents had eaten a few of the vacuum lines in the system. My 68 is in storage and not driven on a regular basis. I corrected the problem and added copious amounts of rat poison around the car. You may not have a problem with rodents, but a 30+ year old car's rubber lines may not be in the greatest shape. Best of luck, Jerry

amcom6

The wiper switch does use an electrical ground. I had an erratic operation problem with my wiper door that was caused by a broken bezel. (not getting a good ground all the time) There is a week spot on the instrument bezel that is susceptible to cracking. It’s something that is easy to check

Hammerhead Fred

Before you go to alot of trouble you should verify that the above mentioned check valve is functioning correctly FIRST!
Your original post describes EXACTLY what happens when this check valve is weak. It's also cheap, easy to replace, and easy to check.

To check it simply pull it out of the vacuum line and, using your choice of hygienic method, attempt to blow through the single port side of the valve. If you cannot blow through the single port side but can blow through the valve from the dual port side then your valve is functioning correctly. Alternatively, you should be able to suck air through the valve from the single port side.

Its basic function is to allow the engine to draw down/store vacuum in the vacuum reservoir AND prevent that build up of vacuum from being lost when engine vacuum is less than what has been stored in the vacuum reservoir. Your wiper door and/or headlights rise due to vacuum loss. This is a safety feature of your car which allows your headlights to operate should your vehicle lose vacuum. In other words, your vacuum system holds those doors closed under normal operating conditions. When you activate either the headlights or wipers the vacuum holding the door closed is released and the door is allowed to pop open. Intuitive eh?

Here's the part!

corvette427

Thanks Hammerhead and Wombvette - I figured let me start where it could be the easiest. I went ahead and located the valve and removed the single side and one of the dual side lines (the second one was pretty well on there, but I figured I only needed one). I then proceeded to blow and suck (go ahead, I'm ready for the comments! ) and all checked out as you described it, so it appears the valve is OK. Funny thing is that I saw what looks like another check valve (single on each side) sitting between the connection to the manifold and the single line entry to the check valve. Not sure if this should be there or if it's part of a visit from Bubba. Haven't had time to check it fully, but I'll see if I can also take a picture and post later. Just kinda strange as I would have expected a line straight from the manifold to the check valve and nothing in between. Thoughts?

yukon988

That's a filter. It should be there and you should be able to blow and suck it with no problem.

Hammerhead Fred

Yukon is correct. The other part you describe is a filter. After so many years there is usually no filter material left in it though.
If your check valve is functioning correctly (it only needs to leak a little to exhibit your described symptoms) then you should next check that your vacuum reservoir tank is not leaking. It should be located just behind the front drivers wheel well. If it will not hold a vacuum due to holes, unattached lines, etc. then you'll not have enough "system vacuum" to operate your wiper/headlight doors.

theandies

Since your check valve checked out your symptoms point me towards the wiper door solenoid located behind the tach. This component gets dirt in it and if the little rubber needle valves don't seat properly there is an internal vacuum leak and causes your wiper door to open and close when the car is started and you may also see the door open when you shut down your engine among other strange operations. Take this out (remember to mark where the vacuum hoses go, there are three ports but only two are used, one port is an exhaust and should have a small fiber filter on it). Taking this baby out and reinstalling it is the hardest part of the job. Drill out the two rivets that hold the can together and disassemble. Note the way everything comes apart. Clean up the needle valve seats (you'll see what I mean when you take it apart). I used rubbing alcohol. After everything is clean, reassemble and get some 1/8 inch pop rivets and put it back together. I am almost 100% sure this will cure your problem. I chased this ghost wiper door operation for a while until I was informed about this little fix. Did this and all my wiper door problems went away.
Good luck. This procedure was on 1971registry.com but it's not there anymore.