VCCA Home Forums TECHNICAL - 1945 AND NEWER 1949-1954 Vacuum wipers

I've been tossing around the idea of converting the vacuum wipers on my 53 to electric but haven't pulled the trigger because of the cost and the non stock appearance of the control knob. I got the idea from another web site to not go electric but to put a vacuum pump and tank off of a modern vehicle on my 53 and connect that to my wipers. I think that's a brilliant idea. I'll get to keep the stock motor and control plus have an infinite number of wiper speeds in all driving conditions. The thread on the other site has people saying they've used salvage yard vacuum pumps out of old Mercedes and Fords and other brands. Has anyone here done this using a GM pump/tank? It needs to be small enough to be able to find a place to mount it. Ideas?

Hi Tiny,

Hope you are doing well.

My limited experience with the 12 volt electric wiper conversions is that they work but can be tricky to install. They are physically larger than the vacuum motor. Most of them are a universal design so you need to make sure you set the pins for the links to the transmissions in the proper position. Otherwise the blades will not have the correct amount of travel arc and parked position.

I like your idea and think it should be pursued. I wonder if you can give yourself some more flexibility if you consider a separate pump and tank design. That gives you options for where everything mounts.

One of the people on a TBird forum made a reservoir/accumulator from a piece of I think 1 1/2” or 2 “ PVC pipe about 2 or 3 feet long. He glued a plain cap on one end. He drilled a hole in another cap and installed a simple bulkhead type fitting, then glued it to the other end. He put a tee into the vacuum line from the engine to the wiper motor and connected one leg of the tee to this “tank”. The engine vacuum created stored vacuum in the tank. So the wipers kept working for a while from the stored energy. He mounted the “tank” on the other side of the frame rail under the body.

You could do something similar with a 12 volt pump and your own tank. You could install 2 fittings in the tank. One connects to the pump and one to the wipers. Of course you would have to plug the current line from the engine to the wiper motor.

After I read the TBird post I have been considering a simple test with a PVC tank on my car just to see how it affects wiper performance. You might remember that in the late 60’s and early 70’s Ford used what looked like a #10 tin can as a vacuum accumulator. This was the time frame when they were starting to use vacuum actuators for heating and air conditioning systems as well as emission controls. They wanted a more consistent source of vacuum so things operated smoothly and immediately. The accumulator can gave them that. In the 80’s VW and Audi had a vacuum tank that look like a plastic molded egg container.

The more I think about this approach the more I like it. I've been looking at different vacuum reservoirs on line and they come in all shapes and sizes plus the possible home made variety you mentioned. Pair that with a 12v pump & add some line and I should be in business. I just need to make sure the pump shuts off at a given pressure. I guess my next question is how much vacuum does a stock 235 pull? I don't have a vacuum gauge but if I remember right most automotive applications are in the neighborhood of 20psi???

Most naturally aspirated engines even today will pull about 22" hg under the best conditions. Most of these old Chevy 6's pull about 19" at idle. If you close the throttle quickly you might see a 25" spike on a gauge. Worn engines or engines with a high lift/long duration cam might pull 16" maximum.

I also was thinking about whether or not you need a control switch. One approach I would consider is a hidden toggle switch to run the pump only when you need to use the wipers. The factor to consider in that system is whether the pump has some type of relief valve to prevent overloading it.

Would adding a vacuum tank be sufficient? I know the mid 90's 4.3 Blazers had the small vacuum tank, but unsure if there was a separate vacuum pump.

If the car was very original, I would have a hard time modifying it. I know there are times rain happens, but I typically don't drive my old cars in the rain if I can help it. I just keep the windshields clean and apply rain-x. While the vacuum wipers certainly aren't great, they usually work ok.

If you end up adding this equipment, please share photos.

Rusty, I thought the OEM vacuum pumps had pressure switches built in and shut themselves off when at the set vacuum. Is this not correct?

Hi Tiny,

I have never studied those pumps. It would not surprise me if some had switches built in and some did not because there was a separate switch in those systems.

I now remember that I had a 1982 Audi 5000. There was a vacuum pump that sat inside the spare tire in the well. Audi installed it as a vacuum source to operate the door locks. Somehow the system would determine when it needed to run to operate the door locks. I don't think I have that shop manual anymore It had wiring diagrams so that would possibly give us a clue.

https://newportwipers.com
Newport makes a variety of electric wipers that have an adapter to keep your stock knob.
Took me about an hour or hour and a half to install in my '50.

I converted to electric and modified the stock switch to accept the electric switch. Been awhile but think I drilled the stock switch and slipped it over the shaft of the electric shaft. Of course the washers won't work this way so I installed a push button and went with electric washer. My car is not stock but I like to keep it close. It is a daily driver so some compromises had to be made.