Cracked Fuel Tank

[cass_cass94]

Hey guys and gals

Noticed today that there is a small crack in the long range tank on my 2011 patrol. The crack is on the front side of the tank and is about 10mm long going horizontaly. Would like to get it sorted pretty soon as it leaks when I fill the tank up past a certain point.
Just wondering how it can be fixed and if I would be able to do it myself or would have to take it to somebody.

Thanks in advance

[Bigcol]

best Idea would be to take it to someone - but they will tell you what you already know - its stuffed

quick fix, which will get you out of trouble in the short term

thoroughly clean around the crack, all paint, dirt, fuel, etc
get a stick of Palmolive soap
rub it into the crack as much as you can

leave it for awhile, then jack the rear up, so its at an angle you know the fuel will be over the crack
if no leaks - good, clean around the area well, and use some Kneed It over the top of the crack
http://www.selleys.com.au/putty/epoxy/knead-it-multi-purpose/
if leaks - not so good


the above will get you out of trouble in the short term, as I said

but

best Idea, take it in and get it fixed properly

[BigRAWesty]

No offense but if your asking how I'd take it to a welder.
They'll need to clean the tank out and then weld it.

[mudnut]

There are some of those two part putties that should suit a fuel tank. I used some on a steel fuel line that lasted for years but .
is really just a quick fix. As Kallen wrote an experienced welder should fix it.
I would also check the tank mounts to find out why it started cracking in the first place.

[Hodge]

Graham Cahill recently used that 2 part putty that literally turns into solid metal over the crack in his diesel tank. It was on their Kimberley DVD, but the fix was only worth a day or so driving.

[dom14]

I'm just wondering the reason the epoxy putty doesn't work on steel tanks.
I've used epoxy to patch up a jerry can. It's been going for years without leaks.

How would a long range tank crack?!!! Must be from an impact!

[cass_cass94]

Yea looks like it might have been from a rock flicking up

[rusty00]

Weld it up.
If you can get to the crack while the tank is still in place.
Drain fuel 100%, make sure it is all out and purg with exhaust gases or warm nitrogen gas.
Once purged and dry and while being purged you can weld in place.

[BigRAWesty]

Yea looks like it might have been from a rock flicking up
So any progress?

[dom14]

Weld it up.
If you can get to the crack while the tank is still in place.
Drain fuel 100%, make sure it is all out and purg with exhaust gases or warm nitrogen gas.
Once purged and dry and while being purged you can weld in place.

How do you "purge" with exhaust gas? Where do you get nitrogen gas to purge the tank?

[BigRAWesty]

How do you "purge" with exhaust gas? Where do you get nitrogen gas to purge the tank?
Plump your exhaust to the fill hose and undo every hose to let the exhaust gas out..
Nitrogen from a gas supplier.

[rusty00]

Use a longish hose or run the hose through a bucket of water as they can get Dam hot.
Any BOC, Supagas or air liquide outlet can hire you a cylinder, but exhaust gas is the cheapest option.
As you won't have fuel in your tank to run the car use a motorbike or mower.
It's all the same.

[dom14]

Use a longish hose or run the hose through a bucket of water as they can get Dam hot.
Any BOC, Supagas or air liquide outlet can hire you a cylinder, but exhaust gas is the cheapest option.
As you won't have fuel in your tank to run the car use a motorbike or mower.
It's all the same.

Purging of the petrol tank is done to get rid of any left over petrol in the tank, right?
So, it won't "explode" while trying to weld the crack.

What if, after draining all the petrol, I leave the tank out in the sun for few hours for any left over intank petrol fume to get out??!!
I understand that means pulling the tank out. But, I always thought, in order to do a proper welding job of satisfaction,
having the tank on a bench is the ideal thing. Welding stuff under a vehicle(with no access to a hoist) is easily said than done.
While doing welding work on the van chassis(no hoist). I had to use quite a few of tree trunk cut outs to raise the van high enough to be able to do all the welding work. Even with that, it was a bitch of a job. I use the same thing to raise the rear of the vehicle high enough when I was doing the rear diff center.

[rusty00]

It won't rid the tank of fuel, but it will creat an environment where an explosion can't happen by removing the oxygen.
If you have no oxygen then no fire can start.
It is best to remove all fuel any way you can to be sure and to make sure you are happy with the process.
If you have a mig welder and can access the tank crack you will be okay as long as you can squeeze yourself or the welder in place.
We use to use this method to cut tanks in half and weld when fitting gas tanks and also for repairs.
Never ever had a problem.

[mudnut]

Since the crack was due to a stone, would you drill a small hole at each end before welding it anyway?

[dom14]

It won't rid the tank of fuel, but it will creat an environment where an explosion can't happen by removing the oxygen.
If you have no oxygen then no fire can start.
It is best to remove all fuel any way you can to be sure and to make sure you are happy with the process.
If you have a mig welder and can access the tank crack you will be okay as long as you can squeeze yourself or the welder in place.
We use to use this method to cut tanks in half and weld when fitting gas tanks and also for repairs.
Never ever had a problem.

That means the tank has to be air tight while welding, otherwise oxygen would squeeze in, regardless of the purge.
Why wouldn't oxygen get into the tank from the very crack you're trying to weld??!!

[dom14]

Since the crack was due to a stone, would you drill a small hole at each end before welding it anyway?

I'm bit lost!!! Drilling into the tank?

[mudnut]

When we had cracked components on locos or whatever, we would drill a hole at each end if possible so that the crack would not continue after the weld was done.

[rusty00]

That means the tank has to be air tight while welding, otherwise oxygen would squeeze in, regardless of the purge.
Why wouldn't oxygen get into the tank from the very crack you're trying to weld??!!

No, just purge it or wash out all the fuel or take it to a professional.
The crack has nothing to do with the oxygen, you are removing the inner space oxygen with the purge.

[dom14]

No, just purge it or wash out all the fuel or take it to a professional.
The crack has nothing to do with the oxygen, you are removing the inner space oxygen with the purge.

I'm sure you are right, as you have experience of doing it. I'm only trying to understand as I haven't welded a petrol tank before. I' guessing you use exhaust gas to purge any left over fuel(from hot exhaust gas)?
Or do you need to keep the engine running, while the exhaust is attached to the petrol tank & while you're welding?

[Bigcol]

thats why he said use a Mower or a motor bike for the exhaust - you have taken the tank out, so the car will not run

if you "purge" the tank with the exhaust, you are replacing all the oxygen (flammable with petrol fumes) with carbon monoxide (which is not flammable)
especially with a tank being welded

66729

so by taking the oxygen out - you cannot have a fire

[rusty00]

All good, it can be daunting the first time.
Exhaust gas is used to remove oxygen more so then remove excess fuel.
If the oxygen is removed then there can not be an ignition of fuel.
Yes keep the purge running while welding.

YouTube has some average videos with a nutter using CO2, this is also good to use just not how it is done on the video.
There are also some sites on the net that can assist with technique.

[rusty00]

thats why he said use a Mower or a motor bike for the exhaust - you have taken the tank out, so the car will not run

if you "purge" the tank with the exhaust, you are replacing all the oxygen (flammable with petrol fumes) with carbon monoxide (which is not flammable)
especially with a tank being welded

66729

so by taking the oxygen out - you cannot have a fire

Very good example.
I deal with liquid oxygen and cryogenic liquids at work along with LNG submersible pumps that have exposed electric motors submerged in LNG, no oxygen no problems.
Hard to believe that 415 Volts running through LNG will not ignite.
Something I drum into the guys working on LNG equipment, purge first with N2 then introduce the LNG, make sure no hydrocarbons are present with any form of high purity oxygen.

[dom14]

All good, it can be daunting the first time.
Exhaust gas is used to remove oxygen more so then remove excess fuel.
If the oxygen is removed then there can not be an ignition of fuel.
Yes keep the purge running while welding.

YouTube has some average videos with a nutter using CO2, this is also good to use just not how it is done on the video.
There are also some sites on the net that can assist with technique.

Yeah, I understand now. Once I realized the purge need to be running while the welding goes on, made sense to me.
I simply use a motor mower exhaust gas for purge. It's a good technique. It comes handy with many welding jobs similar to this.
Thanx