Oh oh, water leak

Thanks for posting back with your solution and success.

Update: I took the trailer out again last weekend. Light rain all day Saturday and.............................................NO WATER INSIDE! I think the problen is fixed. Thanks again for all the help!

Sounds like you are already done. Glad you found it.

The right way would be to pull the water heater out of the opening a few inches, then do the putty tape repair. Then caulk over it. For future readers, caulk is an extra defense. Putty tape is supposed to be the main barrier.

Since you only did the caulk, be sure to keep an eye on it in the future.

Also, take a look at the bare screw heads in the WH flange. If the putty is lacking behind them, they will be a source of leakage and eventual rot. You might want to caulk them now. Back each screw out a bit, put a small blob of caulk (size of a pencil eraser) on the screw, and snug it back up.

Well, here's what I've found.
I pressurized the system and heated the water, and couldn't see any water leaking or accumulating anywhere. I let the water cool down and repeated the procedure - still no sign of a leak. YEAH!!! Everything was drying out. I went outside and carefully checked the seal between the heater and the sidewall of my trailer - there were voids! I guess with all the heavy rain we had this past weekend, some of the water found the void and invited itself inside my trailer. No rain today so I'm going to reseal the heater and hope for the best.
Once again, I want to thank everyone for the ideas.
Fingers crossed!

If it is an exterior leak, you remove the leaking item, clean the sealing surfaces. Apply butyl putty tape to one side, and screw the item back to the trailer. Then for extra credit you might drape a bead of Geocel ProFlex caulk over the top of the flange seal, and down the sides a bit.

I'd wait on the caulk until the putty tape has squeezed out for a good while. Otherwise when it does squeeze out, it will dislodge the caulk. Anyway, there is lot of info on RV sealing and caulking here, on Youtube, etc.

And I'll agree with NO, don't use silicone. Use the ProFlex or something similar.

Silicone is an excellent sealant when asked to seal between two mating surfaces not exposed to weather and UV degradation. It is very poor to use as a sealant on exterior RV surfaces, it will degrade in time and the bond where it is applied will fail. This results in a bad seal and a film of silicone that must be removed for adding more sealant, even fresh silicone as it will not bond to the cured silicone.

I've had very good results with Geocel polymer sealants. They are applied just like typical silicone residential sealants, using a caulking gun. Geocel makes a few sealants for RV and mobile homes. One of these is Geocel Tripolymer Proflex RV. I used Geocel 2300 Construction Grade, a cousin of Proflex RV and results were excellent. Exposure to weather for 4 years continually has not caused any bond failure or lifting. I am now using these Tripolymer sealants in other applications as they have proved their durability to me.

Hopefully, a leaking flange or poorly positioned cover is the cause of your water intrusion. Beyond that, posts above helping to diagnose a fitting leak are the best help. A bad aluminum tank would be far down on my trouble shooting list. Good luck with that nasty water experience.

Silicone doesn't adhere well to metal or fiberglass, it's a dirt magnet, and if you ever have to remove it, it's a PITA. Dicor is better.

John Wayne wrote:
If an exterior leak DO NOT use silicone to repair.

What do you recommend and why not silicone?

If an exterior leak DO NOT use silicone to repair.

Thanks for all the great ideas. Yes it rained all weekend! I hope it's as simple as the exterior leak!
We just got home after a very soggy weekend - both non stop rain and a water leak!
I plan to start digging into the problem tomorrow, and I'll post my findings.
Thanks again to all for the help.