Bigfoot tank box questions

[Wooleysteve]

I am new to the forum but hope to find some answers here.

I just bought a 2006 25B25RQ Bigfoot and can't figure out how to fix the Tank box mounted below the floor. The #8 screws are coming out and replacing them with #10s bedded in loctite doesn't seem to be the answer.


The box is built with flat fiberglass panels screwed together surrounding the tanks but I can't figure out what the screws are supposed to fasten into. It needs to be fixed because water can get into the box while towing on a wet road.



Does anyone know how the box is constructed inside or how to fix the problem?


Thanks

[Tony O]

I believe loctite products are designed for use with metal. I had a 25RQ that had a few screws come loose. After closely inspecting the issue you might try the solution I came up with based on the determination that the tank box was made of heavy plywood - perhaps laminated with fiberglass. Instead of using the same holes the screws came out of I moved them over an inch pre-drilling pilot holes with a limited depth bit. Before actually driving the screws I squirted some black silicone into the pilot hole. It seemed to do the trick. I also squeezed silicone into the old screw holes to seal them up.

[Wooleysteve]

Thanks for the tip. If the box is plywood construction as you suggest ( and I think you are right) the screws are placed so close to the edge they must be into end grain. That is not not so good in my opinion.


I might try your suggestion to relocate the screws and then cover the seam with one of those heavy roof repair tapes made for RV's. The screws that seem to be the biggest problem are the lateral seams. The longitudinal seams rest on angle iron welded to the frame at the ends of the box. Those are the ones I replaced with loctite.


The bottom of the box is slightly bowed out (down) in the middle and I a a bit concerned that may be fro water accumulation or freezing. I would drill a small hole to find out but I am afraid I might puncture a tank.


Thanks again

[John in Santa Cruz]

re loose screws in wood, I've always used carpenters off-white glue for that.

[Tony O]

Well, IMHO, drilling a test hole sounds dangerous. I suspect that gravity and the weight of tank contents may have more to do with minor sagging. If there are no obvious signs of leakage I'd say you're safe. As I recall, on your trailer model there is some type of rubberized cover around the black/grey drain valves to allow replacement of the valves should one go bad. I also remember that they were pretty well gooped up with something to keep the area properly sealed against cold air intrusion. If there is a tank leak water will find a way out.



BTW: You could contact Bigfoot and ask how the tank enclosure is made and I suspect they would tell you all about it in short order.

[Wooleysteve]

Thanks for the advice. I took Tony Os suggestion and contacted Bigfoot and got some information. After explaining the situation I was told that maybe there was rot or soft wood in the luan backed panel that surround the tank. They are only 3/16 thick and one solution would be to take everything apart and replace with solid backing for the screws.


He liked my alternative solution and suggested to try it first. Tape the seams with the heavy rv roof repair tape.



I cleaned the surfaces with a spray product made by the Eternabond company and Applied their 3 inch wide tape as directed. I used the aluminum faced tape because I thought it would hold up to gravel on the road. finished the bond with a heat gun and it made a strong finish.


I have used the same stuff on the belly pan of my 61 airstream and it has been to Yellowstone and the Yukon so far.


I think it might be a good fix. If there is rot behind it at least leaks will stop and the air that supposedly circulates around the tanks will dry it out.