I'm not 100% sure about the washers on a '172 Sport' but I expect they are the same as our 1999 RXE 1.6L. If the front AND rear washers are not spraying properly then read on...
Rather than use two tanks and/or two pumps, Renault have tried to be clever and use one pump and a diverter valve to send fluid to front or rear jets. The pump is spun one way to spray the fronts and reversed for the rears. On my clio the problem was the small sliding piston inside the diverter unit, which is built into the pump. The rubber seals had swelled (possibly due to some bad washer additive being used) and the result was that fluid would not flow down either branch. The diverter piston moves one way or the other depending on pump spin direction and it's job is to seal off the unwanted hose/jets. If the rubber swells then it blocks both outlets. I fixed mine by carefully unpopping and lifting the black plastic scuttle gaurd and reaching in and pulling the pump from the washer bottle. I could then carefully dismantle it and shave 1mm off each rubber piston seal using a sharp craft knife. I reassembled it all and hey presto perfectly working washers. Beware...you'll scratch up your windscreen if you don't fix them soon!
Scott Beavis, July 2006
