VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 41 Vacuum Wiper Motor Troubles

I have a 1941 Town Sedan that I am restoring original. I installed new wiper transmissions, new wiper arms, new blades, and an NOS vaccum wiper motor. I also installed a new fuel pump that has a vacuum pump on it to provide vacuum to the wiper motor. The only problem, it doesn't work! The wiper motor works with the wiper transmissions disconnected from the wiper motor. But, once I hook all the arms up, it's like the wiper motor doesn't have enough torque to move the wiper arms. Is this a sign of a week wiper motor that needs serviced or replaced or what? Could an NOS Wiper Motor deteriorate on the shelf and need lubrication or something? What are your thoughts on this?

have you tried shooting a little wd 40 into the motor? it helped on mine.

Yes!

I've had luck using either Marvel Mystery oil or Air tool oil (about the same thing). Take the supply hose off the manifold, have a small cup of the oil and put the hose into it. Then slowly work the wiper motor through its range of motion. You will suck the oil into the motor. You don't need to put much in, just enough to get the leather on the paddle lubed up. Once you have moved it a few cycles leave it sit for a day or two. Then give it a try, if you have the wiper arms on make sure you put some water on the windshield so the drag is light on the motor. You may have to try this method a couple times. Good Luck Don

It's funny you mentioned putting water on the windshield to reduce drag. I was thinking that could be part of the problem too.

While it is true that water on the W.S. will reduce the drag, your wiper motor should have enough power to run the wipers on a dry windshield.

Tell me HOW you hooked up the fuel pump vac assist.There was a big discussion about which way the plumbing went. Mine works great.

Brandon,
First, do you have a good vacuum source on the hose at the wiper motor?

Second, do you have the arms from motor to transmissions hooked up right?

Third. If the above are ok, then take the motor out and take the top off it. The screws are a little trouble but not too bad once you get the hang of it. Lightly oil the paddles edges with something that will not harm them. Neats?

Fourth, if the motor still doesn't pull the wipers, then go back to a regular hook up off the intake. You probably need a double action fuel pump in better condition.

Good luck with it,
Charlie

Wawuzit,

I'll have to look at it again to see. There was an arrow on the pump. I can't remember which line went where. I'll look at it in a couple of days and let you know.

You got my wheels turn inside my head again about that very thing.

Charlie,

I'll have to check the vacuum but I assumed that since it works without wiper drag, then it's getting vacuum. As far as how much, I'm not sure how to test that.

As for the wiper arms hooked to the wiper motor properly, there's only one way that they'll fit.

I'm guessing it needs a little lube.

The fuel pump with the vacuum is brand new. It should run it better than the intake manifold I would think.

I would think the new pump would be alright also. My suggestion was more in line with helping to isolate the problem than anything else. I've given the problem a lot of thought and I'm pretty much stumped.
Charlie

The double action pump is there to assist when the engine vacuum is very low. The pump supplies a lower level of vacuum than the engine. I have a writeup on this if you want to see the figures. The pump is made so that the engine vacuum will draw through the pump at low RPMs when the engine vacuum is high and the pump output is low.

An NOS pump can be defective because of aging material. NOS ian't always the best.

I found that a lot of NOS parts maybe defective because of shelf life and age. seals for instence, the rubber may have dried up setting on the shelf in the box. but since they never been installed, a lot of people think they are just like new.

If the wiper motor in unhooked you should be able to cycle the wipers back and forth without to much effort.
If the wiper motor works without things connected and with the stuff connected you are loosing vacuum, either inside the pump or possibly the line coming into the car. The paddle inside the pump has a leather seal on 3 sides of it. If its dried out and not sealing the pump will not have any power. You might also want to check and make sure that the wiper switch is actually moving the slide on top of the wiper motor correctly also. Don

A healthy vacuum motor with no arms attached is very difficult to stop with one's fingers.

I'm not suggesting doing anything with your fingers while the motor is being operated with a vacuum supply. I was suggesting moving the wiper arms back and forth by hand, no vacuum to motor.

Old216,

Are you saying that the manifold vacuum hose is hooked to the vacuum on the fuel pump, then to the wiper motor?

Clarification: I was pointing out that a healthy vacuum motor produces a lot of force and actually I was testing one on the bench one day and got my finger caught, and it hurt! They are difficult to resist with human fingers when they are moving.

The side of the pump that draws air or produces vacuum is hooked up to the wiper motor. The outlet that expells air is hooked up to the manifold. When the manifold vacuum is higher than what the pump developes, it draws through the pump.

I have found the information on the vacuum pump/wiper motor setup online. This is a link into the 1948 to 52 Truck Shop Manual but the setup is the same. Fuel and Vacuum Pump If you read through the section it explains how it works, how much vacuum the pump produces by itself and how to test it.

Wow! Thanks! I was under the impression that the fuel pump could operate the wipers by itself. I think I just found my problem. I don't have enough vacuum and need to run the line from the fuel pump to the intake manifold. Plus, I'll lube the wiper motor too.

Thanks so much!

With a vacuum motor in top shape, your wipers should run on just the pump. In my case they slow down to a crawl when I am going up hill. Before they would just stop. I think if I had a vacuum motor in good condition, it would just carry on as always.