Water Tank Level Sensor is Leaking

There is a simple fix. Get a small pipe plug from hardware store then drill out and plug the old sensor. Get a new rubber plug type sensor and install at the same height as the old. But if it's in warranty, let the dealer fix it.

It's likely that the installer over torqued the screw and spun the metal insert. If that's the case, trying to tighten the screw would make things worse.

The best option would be to get the tank replaced under warranty.

If it's the polyethylene that is leaking, that is a much bigger issue. Maybe you could use a Uniseal slip fitting to block the existing fitting/opening by cutting a larger hole with a hole saw and inserting the fitting. Then drill a new hole for a sensor next to it. I think I've seen a similar mechanical type repair fitting somewhere but can't find it. The Tank Depot has them for $7. Harbor Freight has a plastic welding kit for $65 which some have used to repair RV tanks but may take some practice to apply the right amount of heat otherwise could still leak. Best thing would be a spin weld repair. You can buy the driver tool but is $200 plus you'll need a router to drive it. Icondirect has spin weld fittings and drivers here.

Probably best to go to a tank repair shop. But if it's under warranty, get it fixed by the dealer if it's the tank poly that is damaged.

AlwaysDreaming wrote:
As you can see in the photo (which is side ways unfortunately) in the link in the first post, it looks like it is leaking from the center not from the spin welded flange. Here is a link to a picture of the spin weld sensor that is used:

https://www.rvupgradestore.com/RV-Holding-Tank-1-Spin-Weld-Sensor-p/10-1697.htm

It doesn't need a grommet because the screw doesn't protrude into the tank. In other words, even with the screw removed it should not leak. Am I right?

I think the spin weld sensor is leaking between the metal probe sensor and the plastic weld flange? I think when I try to tighten or loosen the the screw the metal probe sensor is twisting as well?

Do you think LeakSeal flexible rubber coating would stop the leak if I sprayed it on the screw and probe in the middle of the spin weld sensor? , has anybody ever used it?

Thanks

You are looking for a simple fix. There is none. Yes, I guess it is possible that the metal threads for the screw are leaking, but we get back to the original debate. The metal nutsert maybe got hot enough during the spin weld process to develop minor cracks and is leaking. Regardless, I don't understand your issue. You state it is under warranty. GET IT FIXED UNDER WARRANTY. Don't try to do a half ss repair. I replace tanks 2 or 3 times a year under warranty for this same problem. There is NO rubber on the inside/backside of that spin on probe. If you remove the wire mount screw, this type fitting will not have water shoot out the hole. It has a rounded solid rivet type backside that senses the water. Doug

As you can see in the photo (which is side ways unfortunately) in the link in the first post, it looks like it is leaking from the center not from the spin welded flange. Here is a link to a picture of the spin weld sensor that is used:

https://www.rvupgradestore.com/RV-Holding-Tank-1-Spin-Weld-Sensor-p/10-1697.htm

It doesn't need a grommet because the screw doesn't protrude into the tank. In other words, even with the screw removed it should not leak. Am I right?

I think the spin weld sensor is leaking between the metal probe sensor and the plastic weld flange? I think when I try to tighten or loosen the the screw the metal probe sensor is twisting as well?

Do you think LeakSeal flexible rubber coating would stop the leak if I sprayed it on the screw and probe in the middle of the spin weld sensor? , has anybody ever used it?

Thanks

Does anyone have a picture of a spin weld sensor and attaching screw?
The weld seems good. That is, it appears to be leaking where the metal screw is threaded in.
Does the metal screw go all the way through into the tank?
Is there a grommet?
Thanks

Those are spin welded sensors. They are basically melted to the tank. The screw just holds the wire.

You might try an auto parts store, they sell repair kits for plastic window washer fluid tanks, overflow tanks, etc. that would probably work better than silicone sealer. The other alternatives, as Doug says above, are a plastic welder--many auto body shops are equipped to do this--or a new tank.

It is not the metal threaded section leaking. The fitting is "spun" on to the tank and that spin on fitting is leaking. When you spin the fitting the friction of the fitting and tank heat up and that melts the tank and when you stop the plastic cools and is then welded in place. The normal fix is to replace the tank with a correct new tank. You could try to find a plastic tank welder and see if he could weld the complete fitting water tight and then install the standard well nut sending unit as shown in the other posters response. Doug

Moved to Tech Issues forum from DIY.

Thanks, I am wondering if there is hardware on the inside of the tank to which the screw threads into?
I am guessing that there isn't since the tank has no opening. Looks like they drill a hole and epoxy in a plastic threaded piece with a flange to which the screw with wire connector and grommet screws into. I am worried that the plastic threads might be stripped, and the grommet won't compress. Maybe RTV/Silicone would work in place of a compressed grommet? Any suggestions on what to use? See the picture in the link in the original post.

Thanks