A while ago there was a thread regarding petrol tank repairs. This one came to me on Tuesday. I'd seen the car on drive it day and offered to repair the leak which the owner found on filling the tank above half-way.
He mentioned he was a foreman mechanic so I thought he'd know what he was doing and didn't raise the topic again...
Very lucky not to be wearing it!
He's very lucky if he wasn't seriously hurt when that went bang. A friend of mine had a fuel tank go out through the wall of his asbestos garage when he was brazing up a pinhole in a tank he thought was clean.
The couple of times I've worked on old fuel tanks I've always steamed them out before filling them with water to just below the repair area. Even after gingerly poking the lit torch down the filler hole before starting work I've not found them a relaxing thing to be mending.
The only time I have exploded a tank was a controlled test to see how dangerous it would be to weld a tank. Then went on to weld many tanks without risk. Fill the tank more than nine tenths full with water, with the bit to be welded highest. Sometimes get flames a few inches high, but never for long, and never an explosion.
May I use one of your photos Duncan to send to the PWA7 magazine as a warning on what not do. I always remember a talk on tuning Seven engines which started off by explaining that pound for pound petrol is more explosive than dynamite.
12-05-2019, 12:23 AM (This post was last modified: 12-05-2019, 12:29 AM by Duncan Grimmond.)
Roland & Dave, sure, use the photos. I hope they serve as a warning.
My technique for soldering a pinhole or patch (using a gas-fired iron) has been to run a vacuum cleaner hose from a running engine exhaust pipe into the filler tube. Lots of carbon monoxide/carbon dioxide/water vapour to expel any oxygen and if there is no oxygen there cannot be any combustion. A good wash out with soapy water, dry, then diesel or paraffin to remove flux residues and check for leaks.
Most fittings like fillers,drains,gauge mounts and breathers seem to be fitted and sealed by soldering and I think it's best to avoid over-heating with an oxy-acetylene flame.
