Roof - Mushroom Attic Vent
 

What is this thingamajig that I need to replace?

That is a "Mushroom Attic Vent". You can buy them at Amazon, Walmart, RV Stores and such. There are two pieces to the ones you typically buy. A "base" unit that is screwed to the roof and coated with Dicor to stop any leaks. The second piece (the mushroom) screws onto the "base". You use the new mushroom with the old "base". There is no need to replace the base.

Some tips:
o - Paint the new mushroom top to keep it from being destroyed by the UV light.
o - Someone here (Daryles) had a link to a place where you can buy just the mushroom piece. Here is the link. It is only $5.99 but shipping is extra. Amazon gets $20 for the 2-piece model.
https://rvandmarine.com/product/mushroom-vent-cap-only/

brilliant! thank you very much for the links and addn tips.

it just screws right off...:)

You can buy just the screw on top
Black ones last longer.

attic mushroom vent cap
https://www.rvandmarine.com/product/...vent-cap-only/

Buy 2
 

I have just had the same problem. I ordered two since there is one in the front and one in the back. They just came today. It looks like the hardest part is climbing up the ladder.
I think the suggestion about painting them is a good idea. I’m in Arizona and the sun baked everything. My 5er is just 5 years old and these plastic parts are brittle as heck.

I lightly sanded and spray painted my two new caps white yesterday. I think I will wash the roof today…been a while - so up the ladder I must go to see how my roof looks and install the caps. It lives under a shed cover so hopefully I won’t find any surprises. I will inspect the roof caulk after the wash.

I also need to install a new “high power” antenna for my Visionworks rear view camera which has never worked to my satisfaction after I replaced the terrible OEM Furrion camera. They sent me this new antenna with a larger & longer cable which will allow the new antenna to be installed just behind the front cap and permanently fix wireless connection issues to the dash mounted monitor…fingers crossed!