I'm replacing the fresh air intake plenum (aka the lower windshield finisher) on my '04 Disco 2. The old one was all broken up and brittle. I'm about to put it in, but before I do, I'm wondering if anyone knows what the plenum side mouldings are and what they do. I can't find a word about them in the repair manual – they're not mentioned in the discussion of replacing the intake plenum. Can I put them in after I install the new intake plenum? Do I need them at all?

This is the part I'm talking about right here.

 

They cause the rainwater to drain into the door jamb behind the fender instead of collecting in the tray beneath the lower windshield finisher.

 

Could I install it later without having to take off the whole fresh air plenum piece? Seems it goes over top of the plenum piece and underneath the "A" pillars, as best I can tell.

 

Yes. They just slip over the end of the windscreen plenum and are "theoretically" retained by a thin piece of double sided tape. I have to reposition mine every so often.

When I bought my Disco 8 years ago, both mouldings were missing. I didn't even know at the time something was missing until I began troubleshooting water on the driver's floor after a rain. I found a parts breakdown and added the mouldings but that didn't help. I finally traced it to a piece of glass stuck between the wiper motor plate gasket and the firewall from a prior to my owning it accident I am assuming.