I actually bought these, I think the minimum was 20 but whatever, not too expensive.
I foolishly DIDN'T drill a hole and after fixing some leaking plumbing - the pressure was apparently so high that it collapsed in my small interior fresh water tank (we rarely use the external tank but I'm glad I caught this). It sucked in and caused a bulge in the middle so that the wooden door beneath the bed would no longer close, a big hump in the tank and in the bed, all bad, haha.
Since it's relatively pliable plastic I was able to pound it back into a relatively decent shape with a small sledge hammer, but I was really surprised by this failure, and cannot think of what else it could be besides the plugs with no hole. Yes, it's been really hot and really cold in California, but it didn't freeze, only other thing could've been the fresh cold water in the hot plastic tank but you'd think that the vent hole in these plugs (or other venting) would've prevented this, but here I am.
Any advice or feedback would be appreciated,
2006 Roadtrek 210
Thank you!
Theoretically, the whole probably wouldn't even been needed because I am pretty sure there is a vent tube on the top of the tank.
Obviously, Roadtrek decided to put a hole in the plug, most likely because the vent tube is either too small or too prone to getting plugged. I think the vent is probably plugged on yours and the pump has plenty of suction to collapse the tank which is probably what happened to yours as I don't think normal temp swings could do that much volume change.
Many of the vents appear to be plugged based on the number of people we hear about that have problems with slow filling tanks from the door fill point where you use the hose and the plug goes. The only way to get air out as you fill is back up the fill hose if the vent is plugged.
The fresh tank is a lot easier to remove than the black and grey tanks are, and it also is easy to drain and doesn't stink, so if you have the skills, tools, and a way to safely lift the van high enough to get under and also have the tank clear the van bottom to slide it out from under the van. The pump inlet hose/drain fitting screws in, the fill hose is hose clamped on but has silicone sealer on it too so it will stick a bit, disconnect the sensor wires, and then remove the supports and it can be dropped out. I think that would be the only way to get to the vent hose, but it is a real question whether it is worth it because that fill point doesn't burp back and fill as slowly as the rear one as long as the don't push the hose you are filling with too tight to the port so the air can get out.
Generally, the way to re-expand a collapsed tank is to use compressed air to slightly pressurize it . Collapsed fuel tanks were very common in the old days of vehicles because many of them vented through the fuel filler cap, and a lot had a separate vent. People would grab the first fill cap they found, and if they put a non vented cap on a vehicle that needed a vented cap, they got a collapsed tank. Those were sheet metal tanks back then. I dealing with the plastic tank would be similar I think.
You may now have a damaged tank though, depending on how badly it was kinked. The fact that is stayed in place when the vacuum was released is not a great sign. It may crack at the bend points after some number of fill/flex cycles. On the sections you can see, try to look for any place on the bend lines that has changed color to white or a much lighter color of the tank. If there is a narrow line of color change, that would be an indication of damage to the plastic itself and not encouraging. The good would be that filling the tank bends it the opposite direction of the vacuum, so that might help, but still a possibility.
Good luck with it and keep an eye out for leaks. At least they would be clean water so not illegal or a hazard on the ground. If it does crack, a tank fabrication place would be able to plastic weld it. I just had to pull and take in our grey tank because it cracked the spun in threaded bushing at the drain connection, and that is a messy job because you have to also remove the black tank to get it out.
