First, thanks
@varunsinghal for inspiring me to take this up.
Link to Honda Thread.
Never knew cowl cleaning is an easy and essential step in keep the most neglected part clean and rust free. After looking at the location and how close it is to the dash, almost like a spine for it, this is going to be a 6 months cleaning cycle for me hereon.
So, these are things that you will need
1. 13 size socket spanner.
2. Sharp screwdriver.
3. Painting brush with long handle / bristles.
4. Soap water or any car wash solution.
5. Anti corrosion spray or wax that you believe in.
6. Patience.
First, observe the wiper position on the windscreen. If you are not sure, make a small mark on the glass using regular whiteboard marker at the base of the wiper rubber blade. That will act as a guide when you reset your wiper blade after the work.
First, remove the screw/nut cover at the base of wiper. Use the sharp screwdriver and gently pry it on the sides and it will easily come off without fuss. For cars that are old or have never worked on their wiper arms, it will take little force to pry it.
Use the 13 size ring or socket spanner and remove the nut at the wiper base.
Then, here is the tricky part. If you try to pull the wiper arm it will not budge. So, here is the solution.
Place the thumb on top of the wiper arm, rest of the fingers under the arm and push the wiper arm towards the glass with thumb.
This will make the wiper move off pinion, and then pull the wiper up with fingers placed under the wiper arm. Just like opening a car door handle with thumb as fulcrum.
Place the wiper away and now open the hood. You will see the snap on plastic rivets. Marked in red ovals.
Use that sharp screw driver to first pull up the screw off the base. Then pull the rivet base later. Screw marked as 1 and Rivet bottom as 2.
Keep them safe and away from anything that might crush them. The tube for washer fluid has to be removed from its clips so that it will be easy for the cowl to be placed in the space between radiator and air filter box. Now gently pull and tug the plastic cowl and after some pulling, it will budge. Make sure you pull it towards you and now up or down.
You can now see the metal gutter and all the muck that collected. If you see leaves, plastic wrappers remove all of them using either your hand or vacuum. Do not allow it to go into the side panel. Then the usual cleaning with soap water can start. Use the paint brush to agitate the soap water in the gutter and it will help loosen the muck and flush it down.
Allow it to dry normally and then you can dab with your anti corrosion solution. I used Tribocor Anti Corrosion Wax Spray to cover the entire spot and wiped the excess with a face napkin. Smothered it all across the metal part of cowl and below it too. All the screws and bolts I could find.
Then put back everything in reverse order you started with.
Points to note:
1. There are lot of sharp edges since its all sheet metal. So, watch your fingers. I narrowly missed cutting my fingers in few spots.
2. If you don't have anti corrosion sprays or solutions a normal use car wax will do. Nothing to worry.
3. In DZire (2nd Gen) the air intake for A/C is deep and has a firewall for itself. So, there is no way you clean it unless you open the dash. Make sure you don't pour any water into it. Pic of the A/C intake below.
4. Though there is a A/C intake snap on filter in the cowl panel which is removable for cleaning.
Best of luck.