240D algae part 3 – removing the W123 fuel tank and fuel strainer

Over the last few months, I have been dealing with the algae problem in my 240D.   I’ve been quite busy with my trip to Victoria and work, so the 240D has been on the backburner.   However, I am keen to get the 240D back on the road, so started work again in the last two weeks.

Previously, I had determined that the fuel strainer was blocked and pumped out 40 liters of diesel into fuel cans.  I assumed there was not much left.   My next task was to see if I could remove the strainer.

A couple of weeks ago, it was a rainy Sunday and my three kids were bored.  They were keen to come with me to my little warehouse unit and help me out on the cars.   The first step was to get the 240D out and up on the hoist.   The three of them were quite pleased that they were able to push the car out on its own.  Then I showed them how to use the positioning jacks to spin it and position it properly for the hoist lifting arms.

Next was to get the car up into the air and drain the remainder of the tank.  We used a tool to stop the flow of fuel as we disconnected the main fuel hose.  I wasn’t sure how much diesel could flow through the blocked strainer, and didn’t want a face full of it as I disconnected the hose.  It turns out I needn’t have bothered, as only a thin trickle of fuel was able to get past.

We let the fuel drain slowly into a bucket.   We were seeing some debris come out as we drained the fuel, although not a lot at this stage.  I had previously purchased a 46mm socket online.  It required a 3/4″ drive, and so I also purchased an adaptor.   Trouble is, I lost the adaptor and so my new socket was totally useless.  By then the kids were bored and we left the car to drain into the bucket.

A couple of days later, I went back and the bucket had just slightly overflowed.  There was more fuel than I figured in the tank, but I was lucky that it was only a tiny bit more, as there wasn’t a very big puddle around the bucket.   There wasn’t a whole lot of clearance around the strainer, so instead of buying another adaptor, I bought a different 46mm socket that could use a regular ratchet.

Even with that and a wobble extension, it was hard to get enough grip on the strainer.  Even when I could, and using a long breaker bar, I was unable to get the strainer to move, the socket would just come off.   I spent (or wasted) two evenings trying various ways of getting the strainer to move.

Eventually a friend told me that taking the fuel tank out of his W126 was surprisingly easy.   The W123 is quite similar to the W126 in that regard, so I decided that I would remove the tank.

Yesterday I went and started that process.  It really wasn’t so bad and I should have done this earlier.   I found this article from dieselgiant the best.   It is quite simple.  While the car was still up in the air, I removed the hoses for the return line and breather.  They were quite hard, so I will replace them.   according to the EPC, they are both supposed to be 120mm in length.

Next with the car on the ground, the divider panel comes out with an 8mm socket.  There are four bolts.   There is no need to remove the carpet backing.   Most of the guides tell you that you need to remove the first aid box and disconnect the sender from the top.   I didn’t, and it was quite easy to remove it from the boot.

It looks like the tank will clear the vacuum reservoir that sits above it, but it won’t.   It is held on by a plastic fastener that I removed with a trim removal tool.   There is enough slack in the vacuum line to put the reservoir to the side.   I also found it easier to remove the right hand side boot liner, which is moulded plastic.   There was one plastic fastener below the tail light.

Its a bit fiddly to get the tank out due to the filler neck.  I found using a pry bar on the right hand side of the tank, as I pull it out from the left was the easiest thing to do.

Once I got the tank out, I was able to use the breaker bar and my 46mm socket to get the strainer out.  It was not easy, I doubt I could have done it from below, had I kept trying.   The fuel sender unit was even harder.

It was also interesting to discover that a used fuel tank was installed some time after 2005.  The replacement tank was removed from a 300D 18/06/05.  It is in keeping with this being a fairly low mileage car that saw limited use.

On removal, it was clear why the car was not running well.   The strainer was coated in black gooey algae.   Its surprising it ran at all!   The sending unit on the other hand was very clean.  On inspection, the sides of the tank are also very clean, there is just a layer of gunk on the bottom.   I used a couple of small brushes I had on hand to clean around the area near the strainer, but I want to find something better before I re-install the tank.    I’m not too keen to use water, as I don’t want to contaminate the fuel or cause rust issues in the tank.

My next steps will be cleaning the tank more, and then starting the re-installation. This will include cleaning up the area where the tank goes.