Repairing diesel fuel tanks

I'd try welding the crack, grind flat then weld, a larger metal patch across the bottom where the tank flexes. We also had a 2000 NMMA 4092 on a Spartan with a 150 gallon tank but never experienced a fuel leak. Just air bags, and ball joints.

Retired JSO wrote:
I'd try welding the crack, grind flat then weld, a larger metal patch across the bottom where the tank flexes. We also had a 2000 NMMA 4092 on a Spartan with a 150 gallon tank but never experienced a fuel leak. Just air bags, and ball joints.

That requires removal, and purging. not a fun day.

Spartan says a new tank is near $1700. 4 weeks to delivery

You can weld the tank without draining it. Our local welding shop welds up diesel tanks all the time. In fact, they have done 4 or 5 repairs on diesel tanks for me. The key is to have the tank "FULL" of diesel, Not full of fumes.
It may be hard to find a good "old fashioned" welding shop that knows how to do this, and is not afraid to do this.

Tom/Barb wrote:
Our Newmars fuel tank has a 1/2" long crack in the bottom of the tank. It drips about 1 drop in 2 minutes. Yes it is full of fuel.
To drop the tank requires a pit, or jacking the coach very high. requires 36" clearance under the coach, we have done that once, didn't like it.

How would you repair the tank? the tank is aluminum, welding is an option, but requires the tank to be removed and purged. I've welded diesel fuel tanks before but I time they will crack again beside the weld.

I now have an EPOXY patch on it, to stop the drip. but don't trust it to stay. ( the tank flexes that is what caused the crack)

Anyway Ideas ?

I once had a pin hole leak in a truck's gasoline tank.
Ran it close to dry, then tilted the truck, sanded the metal and applied epoxy.
It was that way when the company sold the truck, some years later.
Maybe if you did something similar and since it is a crack, clean, sand and apply the epoxy, then a strip of paper thin alum. and re-coat it with epoxy, once again.

Welding an aluminum diesel tank is no big deal. I've welded plenty of them on our fire trucks. We purged them but, no nearly as totally as with a gasoline fuel tank which, we had almost none. Some of our fire trucks were poorly designed and shook those fuel tanks to pieces.
As for welding yours and a new crack appearing next to it, somethings amiss here. Unless your tank is poorly mounted which is putting undo stress on a particular area, a new crack should NOT appear, at least within the time frame you own it. But, it's been suggested that you weld it and then put a patch over the effected area, yep, that's maybe what I'd do.
Sure removing the tank is a pain in the a$$ but, do it once, do it right and be done with it and enjoy your coach without fear of dripping and messing up campsites, as well as your own home or where ever you store your coach.
Scott

I understand you concerns. Go to a local Welding Supply Shop and tell them what you have and what the concerns are. There may be some new wam-a-dine rod for this repair.

My big concern is draining the tank and storing the 120 gallons of diesel while I pull the tank.

If I'm going to pull the tank, I'll replace it.

So I guess When there is no magical easy fix, I'll buy the new tank, transfer the fuel to it setting out of the coach, jack the coach, remove the old tank, transfer the fuel back to it, then install the new tank, and fill it from the old tank.
And to add, I'd never drive a diesel leaking coach to a camp ground.
I have a drip pan under the area now, and caught less than a half a cup of fuel in 3 days after the epoxy patch.
So it is still leaking after I placed the patch on it.

This is all good info. I'm going to keep my eye on this thread.
My fuel tank is really rusty on the bottom. It's a 90 gallon diesel tank on a 2008 Fleetwood Bounder.
I figure it's only a matter of time before it rusts clear through.

And BTW, we did have a welding shop years ago weld up a diesel tank for us. It too had diesel running out of it.

Tom/Barb wrote:
My big concern is draining the tank and storing the 120 gallons of diesel while I pull the tank.

If I'm going to pull the tank, I'll replace it.

So I guess When there is no magical easy fix, I'll buy the new tank, transfer the fuel to it setting out of the coach, jack the coach, remove the old tank, transfer the fuel back to it, then install the new tank, and fill it from the old tank.
And to add, I'd never drive a diesel leaking coach to a camp ground.
I have a drip pan under the area now, and caught less than a half a cup of fuel in 3 days after the epoxy patch.
So it is still leaking after I placed the patch on it.

Or you could go on a road trip of sorts....:)

Or you could go on a road trip of sorts...

Commically, I agree. But, I don't know how much you've traveled lately but, the roads in America are somewhat less than desireable. We just returned from a 6,400 mile trip around the U.S. and, I'm not sure how or why, I've still got cabinets hanging on our coach walls. Or that I haven't developed a leak in my rusty '04 Itasca Horizon diesel fuel tank. Some of those roads were SERIOUSLY bad, mostly in Michigan.

So the OP, while making a more expensive choice by replacing his tank, is making a smart one. None of us likes this sort of thing. Unfortunately, it happens from time to time. One meets the problem head on and, make an informed decision on a course of action that will help in keeping the coach on the road, or in an RV camp, wherever is chosen.
Scott