Washer jets only work when stationary!

[Casanunder]

I have a 3 year old C200K Coupe and a washer jets are playing up. It seems that the jets will only work if the car is stationary or just crawling forward. If I'm moving, they won't work.

To start with I thought it was freezing in the recent cold weather and the "wind chill" effect when driving, but the jets begin to work the moment the car stops i.e. it's too quick to be heat-soak from the engine. It also happens when the temp outside is up around 8 degrees.

I've topped up the washer bottle level and added the "winter" concentration of fluid, but still no better. I realise the pump motor for the jet should be entirely independant of speed, but I still can't work it out! Any ideas?

 

[television]

Can I nominate you for the horrible fault of the month.
Do you have headlamp washers

Malcolm

 

[merctronic]

they could be frightened of speed,or just a faulty pump.

 

[Casanunder]

Television - no, I don't have headlamp jets - just the ones for the windscreen. If I get anywhere with this fault, I'll let you know. It's driving me batty!

 

[jberks]

Yup, horrible fault of the week.
The jets could be connected to speed. Later Mercs have wipers that are responsive to road speed. E.g. slow wipe drops to intermittent when stationary, wipers linked to washers so they wipe as you wash. In other words there is a connection. It picks up when you go over a couple of mph to put the wipers back on full wipe, which is around the same point that your washers stop working and I suspect this is more than just coincidence. I don't imagine anyone outside the dealership would have a clue on this one as they will need detailed knowledge of the computer setup. Have your cheque book ready.