Holes in sump

[Austin in the Shed]

Hi All

Thanks for the responses.

I would like to keep the tin sump as the engine will probably go in my RK which is mechanically completely original.

Thanks for the offer Robert I may well come back to you.

I’ve decided to have a go at soldering, partly as practice for some fuel tank repairs I need to do.   I have three tanks and two leak!  

Cheers

Howard

Howard,be very careful if going to have a go at petrol tanks,No naked flames,use a large soldering iron,I find Bakers fluid  the best flux and you need clean metal.

[Howard Wright]

Hi Austin

Thanks for advice.  I’m very aware of petrol tank blasts.  The tank I will try and repair has been empty for about 6 months.  But even so I’m going to give it a good rinse through with water.  I’ve got a big copper iron and some Bakers fluid. I’ve just taken delivery of some hydrochloride acid and some solder paint so I’ll have a go with the sump next week.

Cheers

Howard

[Dave Mann]

I won't use Bakers fluid because if you don't get rid of every trace you will have more holes. Sumps and tanks get submerged in Deox C after which you will find more holes but they are nice and clean ready for soldering.

[John Mason]

I soldered a tank some years ago. If soldering fuel tanks take all the necessary precautions I.e. no naked lights and thoroughly wash out the tank beforehand. I also filled the tank with hot water to just below the area I wanted to solder in an effort to remove any petrol fumes. I used hot water so that the water did not act as a heat sink and maybe the heat evaporated any residual fumes from the air pocket above the water. Do not use to hotter water otherwise you have a problem with steam and thus not dry for soldering.
I have also heard or having exhaust gasses passing through the tank whilst soldering to stop residual petrol fumes exploding.

John Mason.

[Duncan Grimmond]

I've never has great faith in Bakers Soldering Fluid. It should be an active flux (as opposed to a passive flux like tallow or resin) but is a bit too watery and weak IMHO.
If you have hydrochloric acid you can make your own flux by adding zinc clippings to a small quantity of the acid until all effervescent action stops. This is known as "killed spirits" and was traditionally the best flux for tinman's solder (60% tin,40% lead). It can be diluted a little with distilled water
All traces must be removed after soldering!
Even though the acid has been effectively neutralised by the process it remains very corrosive and should be used with care and stored in a glass stoppered bottle
If you want some zinc I have a bin-full of scrap zinc clippings available, send an SAE and I will return it with a piece to your postage weight limit.

[Peter Clayton]

When I was about 9, I found a derelict chassis in a field and decided to see if it would run. Being a clever lad I thought I would check for fuel . Unfortunately my method of looking in the tank with a match wasn't the best. Apparently the chassis had been there for several months with no fuel in it. It severely burnt my face. I learnt the hard way. When I ever have to repair tanks I now fill with water and light a wick above the cap to make sure the gasses are all gone. never had one "pop" since .

[andrew34ruby]

I have welded many petrol tanks. Before I ever welded one I wanted to see how bad an explosion was caused. I took a freshly emptied tank , put an oxy acetylene flame to the side of the tank and ran. After maybe 30 seconds there was a big bang, the tank flew about 8 feet in the air and came down again. The tank was all bulged out all over, and with a scattering of small holes with the edges turned inwards.

Welding was always done safely after that with every tank 9 tenths filled with water. A few little flames but never an explosion. Usually welded with oxy, but some with MIG later.

[Duncan Grimmond]

Soldering with water in a tank is difficult as the cold water draws the heat away. I'd recommend (in fact I did on the previous page of tank repairs last year) piping in exhaust from a running engine. This will displace any oxygen and so prevent combustion.