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.

The post 240D algae part 4 – Cleaning the W123 fuel tank appeared first on Classic Jalopy.

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.

The post 240D algae part 3 – removing the W123 fuel tank and fuel strainer appeared first on Classic Jalopy.

It seemed that some of the algae was able to get through the screen in the fuel tank.   As I still had two thirds of a tank of diesel, I figured it would make sense to try and get as much of the algae out as I could, before I changed the screen.   The screen is much more of a hassle to change than the two fuel filters.    Since the car was already down on power after 30km, I didn’t fancy changing filters by the side of the road, so I came up with another plan.

I purchased a cheap oil transfer pump on Temu, plus a bunch of cheap fuel filters.   My idea was to hook the pump up to the fuel tank supply and return lines in the engine bay, with one of those filters and see how much crap I could filter out before I changed the screen.

The cheap oil pump was self priming, which made it a doddle to install in the engine bay.    I wouldn’t consider doing this with a petrol car, but since diesel is not all that volatile, I felt ok doing it with diesel.

Starting the pump, I quickly got diesel running through the system and I could hear a lot of gurgling in the fuel tank.   I quickly noticed a couple of things.   Firstly, the pump volume was lower than I thought, and the filter was not getting dirty.

I am assuming the biocide has further blocked up the screen in the tank with dead algae and this is why the car was down on power.   I ran the pump for about 30 minutes, but the filter stayed pretty clean.

Next, to see how bad my algae is, I moved my setup to the rear of the car and put the inlet hose directly into the fuel tank.   This meant the pump was no longer going through the screen.   The amount of diesel going through the pump was a lot more, pointing to an even more blocked screen.   Surprisingly, the filter was hardly discoloured at all.   My theory is that the algae in the tank isn’t all that bad.   Bad enough to block the screen, but not bad enough that the tank is full of it.

At this point, the only thing left is to change the screen.   Since I had my pump setup, I pumped out 30 liters of diesel into jerry cans.   There is still plenty in there, so I’ll need to get another can before removing the screen.    The filter also allowed me to filter it before it goes into the jerry can, which makes me far more comfortable with putting it back into the tank after I replace the screen.

I tried again with my little remote camera, and I still wasn’t able to see much.   Just some minor spotting on the fuel tank walls, but it looked decent in there overall.

The post 240D algae part 2 appeared first on Classic Jalopy.

I stopped by Repco and bought a bottle of the Penrite Diesel Biocide.   It claims to kill bugs in the fuel and separate water and diesel.   The bottle had various concentrations, but I went for the ‘shock treatment’ – 200ml to treat about 50 liters.    Apparently when it is working, the dead algae can clog up the fuel filters.   I checked the pre-filter after I arrived, and there was definitely some algae caught in the filter.   I don’t know if this is the product working right away, or more from driving 150km yesterday after changing the filters.

In any case, my plan is to try and run most of this fuel tank through, changing the pre-filter if I need to.   Once the tank level gets low, I will drain the rest of the fuel and replace the strainer.   I did a quick check of the fuel tank with my cheap boroscope.  The tank is three quarters full, so I couldn’t see too much, but the walls were generally clean, with some minor black spots in places.   The black spots are likely the algae.

Next, I put the car up on the hoist to check a few things.   My hoist was out of commission for a while, and was finally repaired recently.   Putting the car up in the air, I was really impressed with the condition underneath.   There was no trace of any rust or any damage.   This is in keeping with the overall condition of the car.   Everything looked in pretty good condition.   The fuel strainer had been out before, and the fuel hoses were fairly new.   I also checked he bottom of all the doors and they are in excellent shape.

On the downside, the brake hoses looked pretty old, and the shock absorbers are Monroe, not Bilstein or Sachs.  They seem in decent condition though.   While I was inspecting things, I noticed the steering shock looked a bit old.   I had a spare one on hand, so installed it.

While the car was up in the air, I had a few other things I wanted to do.   First was to clean the water drain for the fuel tank filler.   I had tried from the top, and had not been able to push the debris out.   Pushing a long pipe cleaner up from the bottom managed to clear the debris.

Next I wanted to see if the brakes were grabbing.   A few weeks ago, I noticed the car was quite hard to push.   Yesterday, I noticed the brake pedal get a bit soft after a lot of stop/go traffic.   The first test was to see if the wheels spun freely.   The rear wheels do, but the front wheels had far more resistance than I would like.

Next test was to see if a few hard applications of the brakes made any difference.    The rears were fine, but the fronts were even harder to spin after a few presses of the brakes.  I also wanted to check if the rears were doing anything at all.   A long golf umbrella was useful to press the brake pedal while spinning a rear wheel.   I was able to stop the wheel, and it spun freely after I released the pedal.

Based on this, I want to change all the hoses, and the front calipers will likely need a rebuild.   Mercedes used multiple suppliers, so I had to inspect them.   The front calipers on my car are Bendix, and the rears are Girling.   The Girling calipers don’t seem to be all that common, so its probably just as well that my rears are fine.   Most of the rebuild kits seem to be for ATE or Bendix.

I had to remove one of the rear wheels to inspect the rear calipers, so I gave that wheel arch a good cleaning.   For the other three wheels, I cleaned the wheel arch with the wheel on.   I had a huge pile of debris on the floor by the time I was done.    I also noticed that all four of my jacking points was clogged up with wasps nests.   The jacking points are in good condition, and are now without dead wasps.

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