Rocket331

I searched through a number of threads about vacuum wipers and cannot find the info I'm looking for, so here's another thread on the topic.

The vacuum motor that was on the car was an aftermarket Anco motor and it did not work. We obtained a rebuilt original equipment Trico motor and it doesn't work either. The wipers will swing upward, but won't flop back down again. All cables are properly installed and adjusted. The wipers move freely when manipulated by hand.

Putting a vacuum gauge at the line from the vacuum/fuel pump, the vacuum takes a few moments to build, but maintains 18". It's my understanding that 13-14" should be enough to run the wipers. Both motors were tested using an AC service vacuum pump and they both worked well, but the pump was unregulated and provided about 30" vacuum.

Now that you have the background info, I'm wondering if the fact it takes a few moments to build up the vacuum to 18" is an indicator of a failure of the pump or if that's normal. Could it be the vacuum from the pump builds enough to make the motor work in one direction, but then has to build again to get the motor to switch direction? Or, should the pump provide more than 18" vacuum?

We're not changing it to electric. We want the vacuum unit to work.