240D algae part 4 – Cleaning the W123 fuel tank

Earlier this week, I removed the fuel tank from my 1981 Mercedes 240D.  This was because I was unable to get the fuel strainer out from the bottom.    It turned out to be not such a bad thing, as once I had the strainer out, I could see that the tank was still quite contaminated.

On my last article I had some good advice on how to clean the W123 fuel tank.   Armed with this, I used part of a steam mop to act as a steam cleaner on the tank.   Apparently the steam kills the algae.

I found that the attachment for the steam mop was the perfect size – fitting exactly into the hole for the fuel sender.    This allowed me to put the fuel cap on the W123 fuel tank, sit the tank over a catch container and introduce a lot of steam into the tank.

I spent about 20-30 minutes pumping steam into the tank.   This seemed to soften up the debris at the bottom of the tank, so I put the end of my pressure washer into the fuel sender orifice and was able to blast out the rest of it.   By moving the angle of the pressure washer I was able to get reasonable coverage of the tank and my catch container soon filled up with horrible dirty water from inside the tank.

It was also suggested to use methylated spirits to get the water out of the tank after I cleaned it.   I only had one bottle on hand, and used it to give the tank a good rise.   The next day I came back with some more and rinsed the tank even further.

at that point, looking inside the tank looked far cleaner than before.   Now most of the gooey residue was out, I could see that while the W123 fuel tank was mostly in good shape there was a little bit of surface rust at the bottom.   This is because water is heavier than diesel, so the water sits at the bottom and rusts the tank, and allows the algae to grow.   At least now I have removed nearly all of that.   The picture shows the area of the tank below the fuel sender.   It is a bit worse on the other side, but I have no way of photographing that.

Once I let the tank dry a bit, I used my battery operated blower to dry it out some more.  After blowing a lot of air into all three orifices, I was able to get the tank looking pretty dry inside.   Any leftover liquid should be mostly methylated spirits, not water.

At this point, I also gave the area where the fuel tank sits in the car a bit of a clean while I had easy access to it.

I think I now have the tank as clean as I am going to get it.   I’ve not yet decided if I should use a product to coat the inside of the tank given there is a bit of rust at the bottom.  It’s not too bad, but it’s easier to do it now while the tank is out.   I didn’t see any rusty flakes when I was draining it.    At this stage I am probably leaning against it.