Help with waterproofing lights on the back?

[musigenesis]

Most of the lights on the back of my bus show signs of allowing water in (rust on the inside) and on the outside the heads of their retaining screws are all rusted as well. Here is a pic of one of my lights with the screws out: https://imgur.com/a/bRwJhVe

I'm thinking that to begin with, I want to replace that circular gasket. Are gaskets like this available from any online stores as OEM materials? If not I was thinking it would be easy to cut new ones, but I'm not sure of what material to use. I scoured Home Despot and couldn't find anything like a rubber mat or whatever this material is. Would an auto parts store have something like this?

Or would it make more sense to not worry about replacing the gasket, and instead use auto seam sealer around the base of the light? I could see that being more effective for sure, but I'm worried about how it would look and I'd have to re-do it to replace a burned-out bulb.

How can I keep the screw heads for these lights from rusting? Is that just inevitable? Can I replace the originals with galvanized screws or something?

Also, in my pic you can see something that's pretty common on my bus, where the screws holding on the rails have a bit of rust on them. What's the best way to deal with these?

 

[EastCoastCB]

The rear wall of IC's has several leak points. Usually there's a TON of rust behind those lights. I've pulled the lights out to find the entire inner structure completely gone from rust.

Seal your rear windows and the lights up top. I eliminate the upper lights as I don't need school spec stuff anymore.
Get the rear walls sealed up and put some new gaskets on your rear lights. You can probably find em online or just make your own. My local auto parts store has different gasket materials. Found that out through my moped tuning and repair. Always a gasket to make when you have mopeds.

 

[musigenesis]

The rear wall of IC's has several leak points. Usually there's a TON of rust behind those lights. I've pulled the lights out to find the entire inner structure completely gone from rust.

Seal your rear windows and the lights up top. I eliminate the upper lights as I don't need school spec stuff anymore.
Get the rear walls sealed up and put some new gaskets on your rear lights. You can probably find em online or just make your own. My local auto parts store has different gasket materials. Found that out through my moped tuning and repair. Always a gasket to make when you have mopeds.

I do have a lot of rust behind the lights, but the worst culprit by far is the license plate light - it's mostly just paint and rust below that, which I'm going to have to completely replace with new sheeting.

To seal my windows, should I run a bead of sealer around the outside and the inside of each gasket? I've already decided to get rid of the bottom window on my door (rusted all around).

I'm not actually sure which lights are which on the back end. Are the ones in the top corners (with the sort of gutter over them) something I can get rid of entirely?

 

[Sleddgracer]

Most of the lights on the back of my bus show signs of allowing water in (rust on the inside) and on the outside the heads of their retaining screws are all rusted as well. Here is a pic of one of my lights with the screws out: https://imgur.com/a/bRwJhVe

I'm thinking that to begin with, I want to replace that circular gasket. Are gaskets like this available from any online stores as OEM materials? If not I was thinking it would be easy to cut new ones, but I'm not sure of what material to use. I scoured Home Despot and couldn't find anything like a rubber mat or whatever this material is. Would an auto parts store have something like this?

Or would it make more sense to not worry about replacing the gasket, and instead use auto seam sealer around the base of the light? I could see that being more effective for sure, but I'm worried about how it would look and I'd have to re-do it to replace a burned-out bulb.

How can I keep the screw heads for these lights from rusting? Is that just inevitable? Can I replace the originals with galvanized screws or something?

Also, in my pic you can see something that's pretty common on my bus, where the screws holding on the rails have a bit of rust on them. What's the best way to deal with these?

stainless steel screws don't rust for years

 

[o1marc]

sleddgracer beat me to it, stainless or zinc coated screws. Use sealer on them when installed.

 

[musigenesis]

sleddgracer beat me to it, stainless or zinc coated screws. Use sealer on them when installed.

Like, sealer on the outside after I screw them in? Or a dab on the hole before I screw them in?

 

[o1marc]

Like, sealer on the outside after I screw them in? Or a dab on the hole before I screw them in?

A dab on the threads to help seal any water that might penetrate.

 

[CaptSquid]

Try cutting up an old inner tube to make gasketing material. I'd also go for LED lighting.