Red cap over diesel fill port? Keep or discard?

[Lary0071]

I just picked up a fresh new Cummins 3500 and filled the diesel fuel up, I observed what appears to be a very light duty dust cap over the fill port opening. I removed it and filled the truck, then replaced the cap. Am I supposed to keep this on the opening while not filling with fuel? I would think that they could have made a better quality cover if this is a recommended practice. I'm uncomfortable with these new "capless" fill ports, I worry that water and/or salt may find it's way into the fuel door and get into that fill port opening. Is there a better made aftermarket cover to prevent anything from getting into the port?

 

[jeffn]

I threw my red cap away. I don’t worry about these new fill ports but I do think RAM could have designed this to alleviate the concerns that people naturally have

 

[flan]

Genos garage has a assortment of caps, locking and non locking. You don’t need that red cap, the door is gasketed and the fill tube has a drain in between the first and second flapper if something were to get by the door gasket. I do have a genos locking cap and if there was no genos I’d probably leave that red cap in place just for piece of mind/redundancy but that’s just me. I’m sure not many run a cap and the thought never even crossed their minds.

 

[H3LZSN1P3R]

Thats just for shipping not ment to be kept this is a capless system

 

[Thorvald]

Also a useless system. Ram sells a plastic snap on lid at the parts counter, it comes with a tether so it doesn't get lost. Not the best but better than nothing (or get the Genos).

Judging by how much crap, dirt, dust, water I find in that cover and all over my Ram plastic snap lid, there is no way in hell I'd trust it without it.

 

[Ian745]

I got one from sinister as the genos were never available and i drive a ton of dusty ass country roads, otherwise I wouldn’t have bothered with a cap at all

 

[dredd]

I went with Geno's locking on my 2020, and they transferred to my 2021.

 

[BroKV]

I went with Geno's locking on my 2020, and they transferred to my 2021.

View attachment 19246

That’s what I have on mine. I bought in early May and got the DEF cap right away. Took 2 months to get the Fuel cap as it was back ordered.


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[dslbrnr]

I use the red one when adding DEF just incase I spill some in the fuel fill neck otherwise it stays on the garage shelf