Foam across lower radiator support?

I have seen some discuss this foam behind the bumper across the lower radiator support. Some wonder IF trapped moisture here encourages corrosion of the radiator support. What is the purpose of this foam? Any here removing it for corrosion concerns? Thanks!

 

It keeps air from going around the radiator. I haven’t seen it cause rust.

 

No rust. It also keeps bugs and dirt from collecting on the radiator.

 

I should add that when I installed my SSO Slimline bumper, I had to modify the plastic piece to still cover the bottom of the radiator. You can see the modification on my build page.

 

Everything around that area is made of synthetic high durable plastic so nothing will rust. The rust is underneath by the frame where moisture tends to stay.

 

Agree, plus it protects lower “plastic” part of radiator from rocks that get kicked up. Leave it.

 

I have seen a few pictures of it causing corrosion and degradation of that cross member. I spray that area with wool wax and have not had any issues.

 

I tore my foam out after finding rust under it. Other than reducing wind noise it doesn't do anything.

 

When I first got my 4R I checked under the foam occasionally. I found that moisture (from rainy days, for example) would soak into the foam and it would remain wet for days after a rain. It seemed like a potential corrosion concern. For peace of mind if nothing else, my solution was to spray Fluid film on and under the foam -- basically everywhere I could reach, particularly where the foam contacts metal.

 

I’ll probably do that at my first oil change.

 

I just installed my c4 bumper and discovered this foam piece at the bottom of it. It was wet and filthy. When I lift it up, it was all kinds of corrosion underneath it. I’m inclined to remove it.