Author Topic: Repairing Rusty Petrol Tanks - Sod's Law  (Read 608 times)

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Offline 4129R

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Repairing Rusty Petrol Tanks - Sod's Law
« on: Thursday,October 07, 2021, 01:41:32 AM »
While doing complete nut and bolt rebuilds on 7 Europas, a common problem has been bad rust on the petrol tanks.

Normally it is restricted to the tops, as rain just sits on the top of the tanks, and eventually rusts through the thin paint coating, and the thin metal top. This causes lots of pin holes in the tops, and can cause bad corrosion around the bases of the round filler tubes.

I had to replace an outlet tube in one of the tanks, as the tube was very rusty around where it was brazed into the bottom of the tank. I used a 6mm copper pipe of the same length, and sealed around the pipe as it exited the tank using JB Weld, a two part epoxy resin which is petrol resistant.

When I put this tank in, I accidentally knocked the exit tube, it became loose, so I sealed around the pipe using Araldite, a two part epoxy resin glue, which is petrol resistant.

I let the Araldite cure for 24 hours, put 2 litres of petrol in the tank (E5 99 Octane as the E10 95 Octane is now no longer suitable), and left it overnight to see if it leaked. All dry in the morning, so I put the other 18 litres from my jerrycan in to the other tank so the fuel went into the fuel pump bowl, and left the car for a while while I connected all the ignition electrics ready to set the timing and fire the car up.

Meanwhile, thanks to a partner of my stepson going to a nightclub, she caught CV19, so did her daughter, but my stepson and his step daughter tested negative, so they stayed with us, a long way apart from us in my large barn, while the two who were positive did the 10 day isolation thing. We had to take the 7 year old to school, and during one of these trips, she must have passed CV19 on to me, even though she had tested negative.

I was double jabbed, but I got a cold and a catarrh type slight cough, my wife tested positive, I kept apart from her, a few days later I tested myself and was positive. I felt quite normal but I had no energy, lost my appetite, did no work on the car, and just watched old episodes of The Grand Tour, while I got through the isolation.

Eventually I got a bit of energy back, went into the garage, and there was a big wet patch under the petrol tank. I smelled the fluid, it had no smell, I thought it was water, but I could see it dripping from the outlet pipe. It transpired that while I was self isolating, all 20 litres of 99 Octane had dripped out of the tank, all over the garage floor, and into the pit directly below the car.

Don't panic, don't turn any switches on or off to stop sparks, open the garage doors, open the Velux windows in the garage roof, open up the pit to ventilate the big hole under the car. I left it like this for 2 days, until everything looked bone dry. I took the tank out, and worked out it was harder to repair the outlet pipe than to repair another holey tank I had with the tank gauge hole in.

I ordered 3 sets of JB weld from eBay, then used a long 1" wide strip of metal as a band, resin bonded the band to the tank, held it in place with two very long jubilee clips, left it overnight, added fibreglass matting over the metal band, left it overnight, then painted the tank with two coats of black Hammerite.

I then filled the tank with two and a half buckets of water to the top, left it overnight, no leaks, whoopee. I had attached a 6mm rubber tube on the outlet, put a 6mm drill bit in the tube, and with 2 clamps, the outlet pipe was sealed for the test.

After the test confirmed no leaks, I undid the tube from the outlet pipe, and nothing, not a drip came out. Whoops. Time to clear the outlet tube.

I have done this before using copper wire, but this time, the wire went as far as the tank entry and no further. I tried choke cables, throttle cable inners, but nothing would get more than 2" down the tube. Time for more drastic action.

I straightened out the tube very carefully, then used the choke cable inner, and eventually a slow dribble came out, but not enough to show the tube was clear. Then I used a 5mm drill bit to try to remove the rest of the blockage, and the drill bit broke, blocking the slow dribble completely. Back to square one.

I then tried a 3" nail, that did not work, but dented the tank slightly around the tube.

I then tried a very thin long flat blade screwdriver. That pushed the metal blade into the plastic handle. This blockage was not shifting easily.  I put the shaft in a vice and removed the plastic handle, I now had a 6" metal screwdriver shaft of the right diameter. I then bashed this up the tube carefully, and eventually, water came out at a rate of 1/2 pint in 50 seconds, so the blockage was cleared eventually.

I then attached the 6mm rubber tube and drill bit, left it overnight to test for leaks around the outlet pipe, and now I am about to refit the tank.

Meanwhile, thanks to Brexit, we have a big shortage of lorry drivers, especially tanker drivers, panic buying of petrol and diesel, petrol stations empty for miles around. E5 petrol is very hard to find. Eventually I found a Tesco station with E5, took my life in my hands by daring to show a jerrycan on the forecourt, and put 20 litres in the can.

I will test the tank with only about 5 litres this time. Eggs in baskets.

This seems to be a perfect example of Sod's/Murphy's Law, if anything can go wrong, it will go wrong, petrol leaks, lack of smell due to CV19, tanker driver shortage. All I need now is a plague of locusts. He is hoping for a dry tank, and hopefully to get the engine fired up.



 

Offline Pfreen

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Re: Repairing Rusty Petrol Tanks - Sod's Law
« Reply #1 on: Thursday,October 07, 2021, 04:26:49 AM »
Wow.  You have had a fun Summer!

Things can only get better..  Good luck.

Offline cwtech

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Re: Repairing Rusty Petrol Tanks - Sod's Law
« Reply #2 on: Thursday,October 07, 2021, 05:40:06 AM »
My experiences have proven that gasoline will flow through places that water will not.

Offline 4129R

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Re: Repairing Rusty Petrol Tanks - Sod's Law
« Reply #3 on: Thursday,October 07, 2021, 06:56:27 AM »
My experiences have proven that gasoline will flow through places that water will not.

https://www.jbweld.com/projects/gas-tank-repair

Can you use J-B Weld on a fuel tank?
What you need for a wet repair is JB Weld Autoweld or SteelStik epoxy putty stick. ... Once cured, the epoxy can withstand 300-degrees and 900 psi of pressure, so it will be perfect for your leaky gas tank. This is the fastest way to keep that expensive fuel in the tank and not on the asphalt.

They say it is petrol proof.

Offline BDA

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Re: Repairing Rusty Petrol Tanks - Sod's Law
« Reply #4 on: Thursday,October 07, 2021, 06:56:50 AM »
And some of us are bored…

I’m glad you (and presumably everyone else) recovered and are doing well! Also glad you finally got it all squared away!

Offline 4129R

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Re: Repairing Rusty Petrol Tanks - Sod's Law
« Reply #5 on: Thursday,October 07, 2021, 07:03:25 AM »
And some of us are bored…

I’m glad you (and presumably everyone else) recovered and are doing well! Also glad you finally got it all squared away!

Loss of appetite seems to be the lasting after effect Post Covid (PC). Difficult to remember what life was like Before Covid (BC).

Petrol tank now draining water out at a normal healthy rate, then get all the residual water out and fit this repaired tank.

Offline SwiftDB4

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Re: Repairing Rusty Petrol Tanks - Sod's Law
« Reply #6 on: Thursday,October 07, 2021, 08:32:14 AM »
You apparently have worked on several gas tanks. My experience with JB Weld is mixed. I would not be using it to seal or fasten gas lines to the tank. Welding or brazing gas tanks is the proper way to repair although you have to be careful to rinse out gas fumes thoroughly before heating.

Offline Clifton

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Re: Repairing Rusty Petrol Tanks - Sod's Law
« Reply #7 on: Thursday,October 07, 2021, 09:07:10 AM »
My experiences have proven that gasoline will flow through places that water will not.

I can second this.

Offline Clifton

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Re: Repairing Rusty Petrol Tanks - Sod's Law
« Reply #8 on: Thursday,October 07, 2021, 09:13:38 AM »
 I've welded on many gas tanks. Rinse good and use a shop vac on blow to completely air it out and then some. I also use the shop vac after welding to lightly pressurize the tank and use foamy bubble to leak check.

JB weld is the best epoxy though. Projectfarm did a comparison on Youtube and it comes out on top.

https://www.youtube.com/watch?v=XObmZIbHOzY
https://www.youtube.com/watch?v=XObmZIbHOzY


Offline jbcollier

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Re: Repairing Rusty Petrol Tanks - Sod's Law
« Reply #9 on: Thursday,October 07, 2021, 12:43:25 PM »
+1 on epoxy not being a good repair for a fuel tank.  Solder is a much better choice. 

Offline EuropaTC

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Re: Repairing Rusty Petrol Tanks - Sod's Law
« Reply #10 on: Thursday,October 07, 2021, 11:08:04 PM »
It's true that JB Weld, or rather the epoxy resin, is petrol resistant. I think it's an epoxy that's used in all these tank sealant products.

But so are lots of other things, including plain old fibreglass (remember boy-racer motorbike tanks in the 60s ?) but it's the interface/bond that really matters.  You could submerge epoxy in fuel for a year and it wouldn't change enough to notice but if there's corrosion of the steel then it's game over. Not immediately of course, but it's going to leak again.

Told with personal experience. Back when I ran the Elan as a daily and didn't have much cash, the tank leaked and of course on the Elan it's in the boot. I pulled it out and found the leak was external corrosion around the brass drain plug - a wet boot & galvanic action. I wire brushed to bright metal and laid on some fibreglass while I saved up for a tank, by which time it wasn't obviously pouring out but it certainly smelled of petrol. The fibreglass was fine, it was the bond line that was slowly breaking down, presumably with more corrosion from inside the tank.

Personally I'd weld or more probably braze it in place. A common procedure, the pros would steam clean but I'd probably rinse out a couple of times, overflowing rinses to ensure all air/vapour displacement. Then fill with water to just below where I was welding, minimising the vapour space. Alternatives are to purge with your welding gas/CO2.

To be honest I'd take the opportunity to improve things by putting in a 1/2" outlet in both tanks. Not for fuel to the pump but between tanks because that's going to reduce the "fill one side, wait for the other to equalise" issue.

Brian
« Last Edit: Thursday,October 07, 2021, 11:58:24 PM by EuropaTC »

Offline Richard48Y

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Re: Repairing Rusty Petrol Tanks - Sod's Law
« Reply #11 on: Thursday,October 07, 2021, 11:28:17 PM »
A trick I was told for welding fuel tanks is to put dry-ice into it to displace the oxygen.
This from a guy who welds up very large tanks and is still alive to give advice.