Washer system operation

[jameswrx]

One of the faults on a 172 I've recently purchased is the rear washer not working. When you press the rear washer on the stalk the front washers work instead.

Now, obviously first thing I did was a quick google and found the pumps can be a problem. Bought a new pump from a motor factors (yes I even managed to find a helpful chap who'd come accross the sport washer pump scenario with the part no's being wrong)

Upon stripping the old unit down to have a look, there just appears to be one common pressure feed with the split being dictated by a side floating rubber diverter splitting the flow from the pump between front and rear.

My question is.. What else happens to divert the flow? The pump is one pump with one electrical feed and I'm struggling to see what has the influence over the rubber diverter to switch it between front and rear? Is there a valve somewhere in the front washer tubing that shuts off when the rear washer switch is actuated? I'm sure I'm over looking something blindingly obvious but someone put me out of my misery.

 

[obcuz]

I've never chopped one up but would assume that the motor/pump rotor direction is reversed electrically (three wires), and the rest is done with the mechanical positioning of the output ducts.

 

[jack_davey]

Someone has had it apart at some stage, when they've put it back together, they have got the front and rear washer pipes mixed up

 

[jameswrx]

Someone has had it apart at some stage, when they've put it back together, they have got the front and rear washer pipes mixed up

Can you explain how it switches still?

I'm pretty sure that's not the case though, all looked untouched. Maybe my first post could have been clearer.. When you press for the front, the front sprays, when you press for the rear.. The front sprays again.

 

[jack_davey]

Ah right, more than likely the valve is stuck or been removed on the pump.
Pull the pump out and have a look

 

[jack_davey]

To answer your question, the feed is reverse polarity to switch direction, impeller spins opposite way and the valve moves to opposite side

 

[jameswrx]

If that's the case then maybe there's a fault with the switch stalk then!

I've just fitted the new pump and it's exactly the same aaarrrggghh.

stupid ungreatful car! Annoyed me today..

When accelerating hard in 1st & 2nd (what sounds like) the exhaust is hitting the subframe. After a look online it seemed the dog bone is culprit no. 1. So, just fitted a new dog bone.. Still the same! I see a fair bit about engine mounts being to blame too, but to be honest you can grab the engine and shove it about and it is pretty solid compared to most fwd cars. Don't really wanna do two new mounts and it doesn't sort it.