windshield washer air pump hookup - MCI

[bevans6]

My MC-5C has an air pump type windshield washer pump that is working with a valve assembly on top of the bottle bypassed.  I think the valve assembly is a purge valve that is supposed to drain fluid out of the hoses so they don't freeze.  Right now I have the air supply connected directly to the top of the pump, which sits in the bottom of the bottle, and fluid out directly from the pump to the nozzles.  Does anyone know how the valve is supposed to be connected?  It has two hose nipples on top, one straight up and one out horizontal, and two nipples on the bottom.  I tried a few different ways ( there are only 4 combinations) but they didn't work.

Thanks, Brian

[lostagain]

On mine, there are one small and one bigger line underneath going to the pump, so no choice there. On top, 2 lines the same size, one is air supply from the control knob at the dash, the other to the nozzles. I can't tell which is which at a glance, but that leaves only 2 choices. My manual does not have a good enough description to sort out the air lines, but it explains how the system purges the fluid before and after each application to clean out the lines, as you suspected. (3-24 to 29 in maintenance manual).

Good luck with it.

JC

[Dave5Cs]

Brian my 5C has 2 air fittings on the top, nothing on the bottom. 1 coming in supply air and one going to a Tee and then each side to 2 sprayers. through the switch or water valve at the dash.

Dave5Cs

[bevans6]

I'm going to futz about with it a little more but I've pretty much decided the purge valve is simply broken.  The air pump itself works great, it sits on the bottom of the bottle, air pressure goes into the top and presses down a diaphragm that pumps the fluid out to the nozzles.  Squirts the heck out of itself watering the grass about two feet in front of the bus     I will adjust the nozzles so they hit the windshield and since I don't drive when it's freezing out won't worry too much about the purge valve.

Brian

[Dave5Cs]

Brian won't the tires make ruts in your grass when you water though?

Dave5Cs