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johnhicks · 03-13-2023, 06:53 PM

It's about to get real. We're going to remove and replace the grey tank in a 30-year-old Holiday Rambler DP. Pray for us.

Argosy · 03-13-2023, 07:04 PM

Why?

johnhicks · 03-13-2023, 07:12 PM

One or more leaks that can't be repaired without pulling it, and if we've already pulled it...

The design is that the tank hangs on its flanges, and the outer end is sitting on the edge of a subfloor. Although I don't run with the tank full, years of frame/body flex have apparently progressively split the bottom of the tank on that edge.

Argosy · 03-14-2023, 08:56 AM

Ah, poor engineering. Do you have a plan for the new installation to support it from the bottom?

I've had to do a couple of tank repairs, but I've managed them with eternabond, so far I've dodged pulling any.

Good luck, and keep us posted on how it goes.

johnhicks · 03-14-2023, 07:49 PM

Turned out the tank flange was pinched between the mounting rail and a duct/subfloor thing. Comealongs to the back of the truck and levering side to side for quite a while did it.

Since the flanges on the new tank are a bit thinner we assumed it wouldn't hang up. Note what I did there, "assumed."

The tank is about two inches shy of where it should be, but pounding on timbers show us it's not going any further. So we're rejiggering some plumbing to try to make everything go down the same hole.

More tomorrow.

Argosy · 03-15-2023, 06:35 AM

If you have an air compressor blow out the channels, soak them with Break Away. If you have a steel strip the same thickness as the slot drive it down the slot to clear out the rust.

None of the above, do you have a cold chisel and can you get at the full length of the slot? Put the cold chisel in the slot, give it few good raps. Pry it up and down a little as you take it out. Do that every 6" or so. Open it up a little, it will pull closed when you bolt the tank in.

johnhicks · 03-16-2023, 10:18 AM

Oddly, the rails aren't rusty. Anyway, anything past the first couple of feet is inaccessible.

We accepted that it's going to stick out a couple of inches farther than it should but that doesn't cause any problem. We rebuilt the plumbing that drains into it and rebuilt the plumbing from the tank to the valve, no leaks.

Since we had to cut a water line we got a sharkbite-lookalike connector and hooked it back up...and got no water inside the MH. Checked the valves at the water heater., all good. Pulled the connector off the supply line and got water coming out, so obviously the connector was the problem. The connector had a big flow direction arrow on it that we hadn't noticed and obviously included a check valve although that wasn't mentioned at all on the package, so we turned it around and all's well.

This was a fairly big job. If the tank would have simply slid out like it should the job would have taken two people one day, but it took us two days. I hired a local rv tech for his plumbing experience, but he'd never changed a tank in a motorhome before. I don't think he'll do it again either. Other local mobile techs won't do tanks, leaving only Camping World and one ofther local shop. I shudder to think what either of them would have done.

Argosy · 03-17-2023, 04:20 AM

I've looked at the tanks on every RV I've owned and dreaded the thought doing what you did. Congratulations on tackling it, and having the foresight to come up with the plan to finish it.

BA-in-Mich · 03-18-2023, 06:19 AM

I don't have a problem with mine. I have looked at both the gray and black tanks and realized that if I did have a problem I would have to dismantle half of the inside of my unit and then cut the floor out in order to replace the tank/s. Not a job I would consider doing.