Wobbly steel over water tank

[usuallyalex]

The floor in my 1970 overlander is in very good shape and I'm not planning to take it up as I modernize however I'm confused about how the crossmember that fits over the fresh water tank works. I assumed it went all the way over but I can move it up and down a little - is this normal? Does anyone have a picture of what this looks like without the floor? If it was bolted at both ends I'm thinking it should not bounce like this.

[Belegedhel]

Attached below is a picture of the frame from my '73 (its upside down in the pic). The crossmember over the water tank has a red dot at each end of it for identification. If your frame is built like mine (and it probably was), then that cross member over the water tank should be solid as it should be welded on each end.

If you want to understand what is going on, and repair it, you don't have to tear up your floor. Just disconnect your plumbing and gauges from your fresh water tank and drop the tank by sliding the panel out of the way from below. You will then be able to easily look up into the tank cavity and see what is happening with the cross member. The hardest part about dropping the tank is getting the panel to move. I ended up using a come-along.

Good luck!

[usuallyalex]

Thanks - I'll remove the belly pan and see what it looks like. The floor is solid and everything is dry now of course but looking at the rust on the furnace (see pic) and stain on the floor I do wonder if there has been a bit of water running down around the sink or faucet.

[Belegedhel]

You shouldn't have to remove the bellypan. There is a steel Z-channel that is bolted across the bottom of the trailer that holdes the panel supporting the fresh water tank in place. remove this, and then figure out how to get a hold on the 1" thick plywood panel and slide it out. Be ready to support the fresh water tank, as it just sits on top of the panel. Once you bring the tank down, you should be able to see what is going on. If you have to remove any rivets, you are probably headed in the wrong direction.

Good luck

[usuallyalex]

Hmm. I've not spent too much time under there yet - can't believe I missed the fact that the water tank was on a separate rail! The bolts and screws on the front angle are completely rusted - I'm going to spray some penetrating lube on them now and see how I get on. Worst case I may just leave it for this summer if it's completely rusted up!

[Belegedhel]

If I recall correctly, there are bolts at either end of the Z-channel, and screws or rivets along the length. I wouldn't waste too much time on either of them. The bolts at the ends do most of the work, and they could be sawed in half and replaced. If there are rivets along the length, then drill them out, if they are screws and they won't come easily, just knock the heads off with a chisel. I think you can get access to the back-side once the tank has been dropped, so you can grab them with some vise-grips and move them that way.

[usuallyalex]

The screws came out easily and both bolts snapped but popped out no problem. The Z channel was glued on with what I assume is the Vulkum but it dropped after I twisted it a bit. The wood is huge! And the aluminum backing is sealed all the way round - I'm going to slide a knife round and see if I can get it to budge later.

[Belegedhel]

Yep, the wood is 1" thick, and has probably swollen over time. Mine was in super tight. I slipped a putty knife in all the way around to loosen things up, but it still didn't budge. I eventually grabbed onto the free edge of it with some vise-grips, and then attached a come-along from the tongue to the vise-grips and tugged away. That did the trick. I set up a transmission jack with a square of plywood on it to support the tank as the panel slid out from underneath it.

good luck!

[usuallyalex]

Just to follow up here for any future readers - I screwed a ring into the board and used a come along cable puller to get it out. The tank dropped straight out (be sure to have disconnected the pipes and wires) and I was able to see that the weld had broken on one side of the beam. I'm not the world's best welder but I have to say it's no wonder it had broken - it was a crappy weld with no real attachment on the chassis side!

I was able to jack it back into position and weld it back on pretty easily with a regular MIG welder - the harder part was getting the board back in! There were four wooden panels sitting on the board around the tank I assume to stop the insulation and road dust from the belly getting up through the hole in the kitchen cupboard. These must have been put in place before the floor was laid so they were just sitting there not attached to anything. I had to make some corner brackets to make them into a box to stop them dropping down and blocking the board from getting back into place in the channel. It took a couple of attempts but I was then able to use the cable puller to get the board back into place.

I also replaced what I assumed to have been water fill hose leaks. Unfortunately it looks like the leak was actually in the top of my tank - probably should have tested it more thoroughly when I had it out on the driveway! Ah well, second time will be much easier