Tuesday, 20 May 2014

Cleaning of fuel tank.

If you have read the post towards the beginning of this blog you will have seen how bad the carbs were gummed up after years of standing with unleaded fuel in them.
Well the fuel tap and tank were just the same...
Just removing the fuel filler cap was an effort as it had rusted in place pretty tight, but after squirting plenty of WD40 around it and gently tapping it with a plastic hammer I was able to persuade it to unscrew. Removing the fuel tap also revealed the gum in the bottom of the tank that was like pulling soft toffee apart.
So having seen all this I knew I had some serious cleaning to do and looked on-line to see what was available. Frost Auto restoration had the POR-15 fuel tank cleaning and sealing system which I thought would be just the job so purchased a kit. I had read somewhere else that to clean flaking rust from the inside of your fuel tank, you should put stones in the tank with a  cleaning solution and shake it thoroughly.
I first mixed up a solution of the POR-15 Marine clean and swished that around the tank, before draining it out to help loosen some of that gum.
I then mixed up another lot of the same solution and this time placed 100 carefully selected stones from my driveway, ensuring each one had nice sharp edges to get any flaking rust or old fuel tank sealer off. Another vigorous shaking session, followed by 20 minute rests in between each one, (this rest was mainly for me, not the solution to do its work)! I then left it over night and proceeded with more shaking the next morning before draining and rinsing the solution out of the tank. It was certainly looking much cleaner now.
Now before putting in the next solution, which was a POR-15 Metal Prep I had to remove the stones. I already knew that these stones were to big to come out of the fuel tap hole but thought it would be easy enough to tip the tank upside down and get them out of the filler hole, the way they went in. But that was not that easy. I turned the tank over, shook it all about but not one single stone came out! Oh, bummer I thought, that was not how I planned it. So I went over to my tool box to get my long claw tool and proceeded to go fishing for stones. This again wasn't as easy as I had thought, resulting in only one stone every 4 or 5 grabs, ( I never was any good at fishing, I used to go with my brother, sitting only 20 feet from him on the same river bank and he would be there pulling fish out and every time  I reeled in I just had a tangled mess. I even tried casting into his swim, much to his annoyance, but still didn't get many fish, so this task was going to be a challenge right from the start) but eventually I got all 100 back out!
I then proceeded to using the metal prep solution as instructed and carefully dried the inside of the tank out ready for the sealer.
However, it was at this point that I decided to do some more re-search into sealers as I had been warned that sometimes they can cause other problems. Googling this informed me that the POR-15 sealer was actually OK as it was OK to use with modern fuels that contain ethanol additives.
But what this extra research also told me, was that it was best to remove the old fuel tank sealer, (the matt red finish in BMW tanks), before applying the new sealer. To do this you need to user POR-15 Por-Strip, a powerful paint stripper. The problem with this is that I did not want to re-paint the outside of the fuel tank so in the end I decided not to use the sealer coat as it was not as though I had any leaks from badly rusting parts of the tank. The whole purpose of the clean was just to remove the old sludge and gum which the process so far had done very nicely.

So the tank is clean, now I just have to clean up the old fuel tap and replace the seals within it. It looked like  a simple enough job, but things didn't turn out  how I expected!
I had borrowed a small ultrasonic cleaning tank from a friend, I then used a solution of water and white vinegar, put the tap assembly into this and started it going giving it 2 15 minute sessions, it looked OK but I thought it would be best left in the solution over night before dis-assembling it the next day. I came to get it out the next morning and to my horror, part of the alloy body had just corroded away I  the solution meaning that this fuel tap was toast, oops! Oh, well I will order a new  fuel tap and take this opportunity to get one with a horizontal outlet which I think will make the fuel pipe routing better.

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