How many more
Join Date: Sep 2007
Location: United Kingdom
Step by step, then, it looks like this...thanks to a624v6
The first thumbnail from a624v6 (above), when enlarged clearly shows the arrangement of the wiper blade 13mm nut under the lift-up plastic cover - get a socket on that without a problem, then jiggle cw and acw til it pulls off. Do this with the bonnet closed. From past experience with replacing wiper arms, a dab of white marker on spindle and arm joint will enable a one-shot replacement in the correct geometry position on the screen.
The second diagram image copied below is not a thumbnail so cannot be enlarged...pity.
However, peering closely, you can see that the scuttle plastic panel is in two halves, thankfully only the left side (and just one wiper blade) needs lifting to access the T valve thingy.
There's the big plastic cover over the screw on the edge of the panel (#1 in the diagram covering the screwhead #2); then there are three other #2 screws to remove to free up the left hand portion of the scuttle - they are the out-of-the-way screw on the side edge (best seen in the diagram on the extreme right side #2) and then another #2 in the centre front edge of the left hand half, finally one #2 in the very centre of the front edge of the join between left and right sides. Also note the four plastic hidden underside (see photo black arrows) clips that need gently prising up when the screws are out.
Thankfully as shown on the excellent photo sourced by a624v6, you can just see the T valve poking up and accessible without removing the right side segment. Replace with Lakeviews sourced part (photo above) or ditch the spring and clean out gunge or replace with a fishtank T tube - all seem to work great.
Altogether, a great pooling of forum know-how and research - I hope it is tagged suitably to enable easy searches in future, as this problem is sure to recur with the aging 156 fleet.
Thanks to all respondents
Only 33 1.8 TS Veloces left, and counting...