I’m not a big fan of these liner kits. They can be great for fixing small holes but I feel they don’t offer any structural strength. So if the tank is splitting at the seams it may need the strength of a weld to keep it from cracking further.
The main reason I hate the likes of chemical liners is that it make it nigh impossible to weld afterwards as the liner material will keep trying to come up into the weld causing porosity in the weld.
There are some ‘chewing gum’ type fuel tank repair kits around that may be a good fix until you can find a welder brave enough, if the crack in the seam looks like it might need to be structurally repaired. I generally hate these too as they can be hard to get out of the little nooks and crannys before welding, but at least on the outside of the tank it can be done.
If soldering be aware that if you use a soldering iron that has a gas torch mounted behind it the gas torch may set off an explosion.
I’m not so sure about running engine fumes for hours before welding as the purpose of the fumes is to take away the oxygen which will stop any explosion. Run it long enough to completely fill the tank with fumes.
As for the petrol / diesel thing, it may be that if petrol engine is running rich then it will fill the tank with more combustible material.
Still alive, just,
A repeat post from somewhere else on here…
I have welded many alloy tanks over the years, without a problem, the alloy doesn’t seem to hold the fumes like steel tanks and as it doesn’t glow when welding it has no ignition source.
But steel tanks, that’s another story. I had welded a couple successfully by filling them with water but this can cause dramas too.
You can’t weld when the water backs onto the weld area as you can’t create a decent weld pool, so you need to leave a small air pocket in the weld zone. This worked okay a couple of times but then quite a few years back now I was asked to weld up a small crack in a seem of a stainless steel boat tank. No problem I thought. I filled it full of water, left a small air pocket behind the weld area & proceeded to weld.
I was kneeling down at the time, resting my elbow on the tank. I was doing okay and I just had to get the last little bit when wooooooooopppfh.. It seemed like the blast lifted me to my feet and knocked the welding shield off my head. My heartbeat was suddenly elevated to that of a 20-minute moto, although without the burning lungs.
I then had a very real fear of being electrocuted as the 40 litres of water from the tank gushed over the factory floor and headed for every extension lead. I had to quickly pick up the leads out of the way and then grab a broom to divert the water away from other machinery. Some guys from the factory next door came running in to see what the blast was. It didn’t seem that loud to me, I think I must have been in the epicentre.
And the tank, well it was completely rooted. It used to be rectangular but now all six sides were rounded and every seam had a crack in it.
I had to make a new one from scratch.
In hindsight, I realise now that what traces of fuel that was in the tank floated on the water, the welding heated it into fumes in the air pocket and then when it thought I wasn’t looking the ignition source of the weld pool did the rest.
I still weld many alloy tanks but refuse to weld steel tanks now. Life’s too short and I don’t need to speed up the aging process any more than what it already is.
I have heard that you can run a hose from the exhaust of your car into the tank. The fumes taking away any oxygen that a blast needs. It would confuse the Coroner though, wondering why you suicided in your workshop with your welder running.
