Olds Dad

Okay - I'm a pretty smart guy, but I can't for the life of me figure out how vacuum 'pumps' washer fluid out of the jars.

Here's the setup: There are 2 vacuum stalks on the wiper switch (55 Super 88...many years similar though). One has engine vacuum at it, and the other goes out to the washer jar...when you push the washer button, the engine vacuum goes to the washer jar and (theoretically) pumps fluid onto your windshield.

Mine is currently inoperable, but I just took the 'pump' assembly apart and I can't see how this thing is supposed to work...a couple of seals, a spring, and a plunger - obviously when vacuum is applied the plunger is supposed to move, but the fact still remains that the jar is in a vacuum (due to the engine vacuum being applied from the dash switch)...how the heck does this turn into a positive pressure and subsequently a clean windshield??

Yellowstatue

The big secret is the SPRING...vacuum compresses the spring and you release button...spring extends pushing H2SO4 or whatever you have in there onto the windshield and voila...no more bugs

Bluevista

It's magic.

The things are dangerous, ever try accelerating to get on the freeway in a driving rainstorm in a car equipped with vacuum wipers when they stop or go so slow they don't do anything?
Stevie Wonder would have just a good a chance of seeing anything through the windshield as you do.


"During operation, a vacuum is directed from the control valve to the large diameter cylinder of the pump, causing the piston to move against the tension of a large spring. The movement of the piston, loads the spring, and simultaneously draws liquid into the smaller part of the cylinder through a one way valve, to be dispersed onto the windshield. When the large diameter vacuum piston reaches the top of the cylinder, a small signal valve is contacted, stopping the vacuum application. The spring, having been loaded by the force of the vacuum, pushes the water out of the nozzles and onto the windshield. The water cannot go back into the reservoir because of the one way valve, so it follows another open path, out of the valve, through the hoses and onto the windshield."

That sound right?... beats me.

This place has some stuff about fixing them.

http://www.wiperman.com/washservpage.html

Olds Dad

Thanks...makes total sense now - I was thinking the vacuum was only applied during operation when in fact it is the opposite.

BlackGold

I guess I'd rather have vacuum-operated washers than what VW did with the Beetle: use the pressure from the spare tire to push washer fluid onto the windshield. Stupid idea. Invariably the system would leak somewhere, resulting in a flat spare (and inoperative washers, of course). Even if there wasn't a leak, you're draining your spare every time you use the washers. Just one of many really dumb ideas VW had.

Sandee

Can anyone provide a schematic of the assembly of the inner workings of the vacuum pump for a '54 Olds? I took mine apart and neglected to note what came from where.