Just picked up my 72' so bare with me. Trying to knock out some simple things up front and get parts on the way...

When I start the car the wiper door pops open and never closes. When the engine is shut off the door stays open with no attempt to close. I can force it closed by hand with the motor off, but even then it seems it doesn't close all the way.

I checked the override switch. Interestingly the owner told me that the "wipers used to work...??" Well that center **** under the wheel was turned CCW, I turned it and the wipers sprung to life. I can't really tell if the ORide switch is pulled out or in, but I can't seem to get them to move in either direction to try the other position.

I have consulted the Wilcox diagrams but don't really know where to start. I checked for vacuum on what Wilcox calls the Wiper Arm Vacuum Relay (located under the passenger fender, engine compartment). Vacuum was a little weak but present into the middle nipple, and strong out of the outboard nipple.

Appreciate any help. Thanks!

 

Do you have vacuum at the small port on the wiper relay ?

 

Checked the relay under the passenger side fender again. The forward most port in the row of three does NOT have any vacuum, I see that it is running to the diaphram attached on the passenger side rail just forward of the windsheild. Also, fourth vacuum hose and smallest of the 4 connected to the disc does not have vacuum either.

 

When the 4th or smallest hose receives vacuum the valve will move and close the door. Start back tracing and see why the small hose has no vacuum.

 

Ok, so that vacuum is suppose to come from a relay located under the passenger side grill located right at the wiper arm pivot. This relay has three vacuum lines running to it, none of them having vacuum.

The one that appears to be a source runs forward through the firewall and immediately connects to a metal vacuum line. Tracing this vacuum line I see that it runs over to the driver's side and disappears into a hole in the firewall on that side. That hole accommodates three vacuum lines, one off of the intake and another that is heading down to the headlights. Both of those have vacuum.

So my guess is I need to figure out where this line is disappearing to in the driver's side firewall.

 

Is the wiper arm making contact with the wiper arm shut off valve? If not the door will not close. Located under the wipe arm on the passenger side.

 

Opps, I see that this has already been discussed, sorry!

 

This might help to find where your losing your vacuum. ( Ignore the Pinch line )

 

I don't know if I'm just reading that diagram wrong, but I've tried and it doesn't seem to agree with my setup. I believe the upper left most component is the wiper relay we've been discussing. This diagram only shows three connections, mine has 4 as we've discussed. I'll keep looking at it to try and make it make sense.

On a separate note, Apocolips brought up something I had meant to mention. With the engine off the wiper door is capable of closing when pushed on... BUT it seems something is physically interfering preventing it from closing. With enough force there's a faint snap (like the wiper is adjusting out of the way under the force or something else) and the door closes flush. Without the extra force, it will close about halfway with light pressure and then just stop...

 

The upper left component is the control valve under the passenger wiper arm.
The relay is lower and to the right of the control valve and has green,yellow,red and a small black hose.

 

The wiper control valve or wiper interlock switch as some call it, what you were calling the relay, has 2 active hoses, one with a red stripe, one with a white stripe. The third hose is a solid black vent hose.

There should be vacuum at the red striped hose at all times. That hose gets it's vacuum from the small hose on the check valve indirectly through the wiper solenoid and the wiper door over ride switch.

The relay is under the fender and gets it's control vacuum from the interlock switch when the wiper switch is turned on. The interlock switch moves the valve from the red striped hose to the white striped hose which then forces the relay to move it's switch from it's large red striped hose to the large green striped hose thereby opening the door.

If the door is staying open, the relay is not receiving a signal that it is safe to close the door. In other words, the mechanism for ensuring the door doesn't close on the wipers is in fail safe mode.

The most likely culprit is the interlock switch button, which as stated above, is probably not making full contact with the wiper arm.

If it were, the internal valve would move from the white striped hose to the red striped hose and the vacuum from the white striped hose would be vented off which in turn would signal the relay to change it's valve back to the large red striped hose from the large green striped hose and thereby closing the door.

You can test that by pressing the button on top of the interlock switch with a long screwdriver and see if the door closes.

cc

 

By the way, the over ride switches under the steering column are a two way switch. When pushed up, vacuum is allowed to flow through to the interlock switch and the rest of the wiper vacuum system.

When it is pulled down, the vacuum system is sealed off so that shutting off the engine does not shut the wiper door.

The same principle applies to the headlight over ride switch.

cc

 

Ok, great info guys. Thank you. I am understanding the diagram now. I checked the control valve. First, with the engine running I tried depressing the safety switch further, the door did not move. The washer is touching the switch but it has quite a bit of further displacement it can depress in... still no movement with the screw driver method...

So I checked the vacuum on the control valve again. There is clearly input vacuum going through the red hose to the control valve. However, there is no vacuum coming off the white outlet hose to the relay (the one under the fender).

If I am understanding correctly, the way it is suppose to work is that when the control valve wants the door to remain open it is suppose to pass vacuum out to the relay, from there I'm not sure I understand what's suppose to happen. But it would appear to me the control valve and switch are not the culprit...

EDIT: BTW my override switches are both IN. So that shouldn't be a factor.

 

Just the opposite. The control valve shuts off the vacuum going to the relay to keep the door open.
If you have vacuum on the red hose to the control valve you need to adjust the valve so it will pass vacuum to the white hose when its depressed.

 

Nomar116, if you have access to a vacuum pump you could remove the white striped hose from the wiper valve and connect it to the pump and see if the door shuts when you supply vacuum to the relay.

cc

 

Ok, so I don't own a vacuum pump but maybe I'll have to invest. For the time being I disconnected the control switch input and output, and connected the output (white) directly to the hard vacuum line for the input(red) thereby bypassing the control switch. By providing vacuum in this way the door should close, correct? Well it did not.

In other news, I have noticed two others. First the passenger side washer blade is bent up, which is what is causing an interference I mentioned previously when I close the door manually. Secondly, when opening and closing the door manually I notice a hissss coming from the actuator.

 

Before I go bending this wiper back thinking it could be the problem, I thought I'd share some pics. Looking at the drivers side wiper it looks bent up for sure, but then again the two have different shapes and designs.

Passenger side wiper, looking very bent



Closeup of the passenger side wiper, slight chip in the paint near where this bend is. Possibly from interference with the wiper door?



Drivers side wiper, very straight.

 

I'll just keep up the play by play...

I discovered a capped "vacuum hose" lying just underneath that passenger side wiper. Reading on the forum this is my understanding... That capped line is for the windshield washer system. It is connected to a box on the centerline of the firewall with three hoses fitted to the 10 oclock position (looking aft). Two of the hoses go to each base of the wiper arm...

Which is when I noticed that my driver's side wiper arm has a washer nozzle and all the fittings. The passenger's side does not have the nozzle or the thin line that runs along the arm carrying the fluid.

Another reason this drew my attention was this. The vent line off of the wiper control valve has been connected to the third line into the washer fluid box. I assume this is the input for washer fluid, and not where this vent line goes.

So do I just disconnect this and leave the vent line connected to nothing? Mine passes forward through the firewall by about 3 inches, so do I disconnect it and leave it to just chill there in the open?

 

Yes, the vent line for the wiper control valve just vents into the ether. It's odd that someone would have connected it to the washer system. Obviously by someone who really has no idea what so ever how this system works nor how any other washer system works.

This is why I love this forum. I can't wait to see what Bubba has done next.

cc

 

So any idea whether connecting the white hose directly to the red input, bypassing the control valve, should have closed the door..? I'm stuck..