Camco 40302 Vented Black RV Bumper Cap 4-Inch Square

If you've got a travel trailer or fifth wheel, there's a good chance that hollow 4-inch square tube hanging off the back is pulling double duty as your sewer hose garage. It's a smart place to stash a dirty hose. Out of sight, off the floor, and nowhere near your drinking water gear. And unlike tossing it in a bin inside the trailer, the bumper keeps the mess completely outside your living space. But that storage trick only works if both ends of the bumper are capped. The Camco 40302 is the cap that closes off the open end and keeps your hose where you put it.

Here's the part that matters most. This cap has a vent hole molded right into it. A sewer hose that goes back into the bumper still a little damp will sit in there between trips, and a sealed tube turns into a swamp. The vent lets air move through so the hose can dry out and any leftover odor has somewhere to go. You open the far end, slide the hose in, pop this cap on the near end, and the whole bumper breathes instead of trapping moisture. That's the difference between a hose that lasts a few seasons and one that gets stiff and smelly by midsummer.

The 40302 is sized for the standard 4-inch square bumper, which is what you'll find on the majority of towable RVs. Before you order, it's worth taking a tape measure to the opening. Measure across the flat, outside to outside. If it reads right around 4 inches square, this is your cap. Bumpers do come in other sizes on some rigs, so a quick measurement saves you a return. The cap is a single piece, sold one to a pack, so grab two if you want to do both ends or keep a spare in the drawer.

It's molded from black polyethylene, so it isn't going to rust, rot, or get chewed up by road spray the way a flimsy cap would. Polyethylene has a little flex to it too, which helps it seat into the bumper opening and stay put over washboard roads. Black hides the grime that collects back there and blends in with most bumpers and frames. Give it a wipe now and then and it'll outlast a lot of the gear bouncing around in your storage bay. This is a wear item by nature. The old cap probably cracked, went brittle in the sun, or bounced off somewhere on the interstate, and that's exactly what the 40302 replaces.

Fitting it is about as simple as RV maintenance gets. Clear any debris or old cap fragments out of the bumper end, line the 40302 up with the opening, and press it into place so it sits flush. Some owners run a small self-tapping screw through it for extra hold on rough roads, and that's a fine habit if you've lost caps before, but it isn't required to get a good fit. Keep the vent hole facing out and unobstructed so it can do its job. When you pull the hose for a dump, the cap comes right off and goes back on just as easily.

One more tip from the crew. If your hose still smells after a few trips, pull it out, rinse it, and let it dry fully in the sun before it goes back in the bumper. The vent on this cap keeps things moving, but it works best on a hose that went in reasonably clean to begin with. Little habits like that are what keep the whole setup from becoming a chore you dread at the dump station.

We point weekend campers and full-timers alike to this one because it solves a small problem that turns into a big one when you ignore it. A bumper that's missing a cap drops your hose on the highway. A bumper that's sealed up tight with no vent breeds mildew. The Camco 40302 handles both at once. If you store your sewer hose in a 4-inch square bumper, this is the cap you want on the end, and it's cheap enough to keep a backup on hand for the day the old one finally gives out.