Why Won’t My Nautilus P2.5 Draw Antifreeze When Winterizing?
Updated 08/26/2026 | Published 08/18/2026
Question:
On my Nautilus P2.5 I’ve been unable to get the winterize/sanitize function to work. I’ve heard that you have to flip the inlet screen so that it depresses the check valve nipple. There is no nipple protruding on my check valve like you can see on part number BM58GR. Am I missing something or do I just need to install a new check valve like the part number mentioned above. Hope that all makes sense and thank you
asked by: Eric S
Expert Reply:
Hello Eric,
Welcome to etrailer, I'm glad you found us!
Yes, what you are describing makes sense. On the Nautilus P2.5, flipping the cone-shaped inlet screen allows it to press the little stem on the check valve open so the pump can draw antifreeze or sanitizing solution.
Since that stem isn't showing on yours like it does on the Replacement Plastic Check Valve # BM58GR, it may be missing or damaged. Before replacing it, though, I would like to make sure you have the same style. Please respond directly to the email you receive from me with a clear picture of the inlet with the screen removed and I'll be happy to take a look.
If we confirm it is the same style and that little stem is missing or damaged, # BM58GR is what you will need to replace it.
Getting things packed away for the year, what was your favorite trip this summer?
Product Page this Question was Asked From
Replacement Plastic Check Valve for B&B Molders City Water Inlet - Polar White
- Accessories and Parts
- RV Water Inlets
- Check Valve
- White
- B and B Molders
more information >
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Dennis
8/26/2026
Hi Eric, Interesting. I have never flipped my screen and the winterize has always worked drawing anti-freeze into the system. In fact, I even use the winterize configuration in order to draw more water into my tanks when I'm dry camping and run low.