#1981240d

I've noticed a small drip of diesel under the engine of my 240D after I park it.  On further inspection, it looked like there was a leak around #4 injector.  It was running down the engine block and dripping on the ground.

It looked like the return hose from #4 to #3 was quite wet. Replacing the return hoses seemed a good place to start.  I don't know how old they were, and the are a common place for small diesel leaks.   I ordered a metre worth of new hose. The hoses push on, so this is a pretty simple job.  I had some left over, so a metre would be sufficient for a five cylinder as well.  The only small complication is around the #3 cylinder which is obscured by the throttle linkage mechanism.    I also want to check if the setup at the end of the 4th cylinder is correct, as it was a totally different hose type. After fitting the new hoses, I let the car idle for about 15 minutes and I still had a bit of wetness around #4, so I need to investigate that final hose with the cap on the end as my next port of call.

Led by the MBCACT, the state based Mercedes-Benz clubs are planning a major event for the 50th anniversary of the W123.   The W123 is one of the more significant models in Mercedes-Benz history and so it is an important milestone. I've been slowly tidying up my W123 since I purchased it.  However, I had a couple of last things I wanted to do before the event. Cleaning the wheel wells The wheel wells of a Mercedes-Benz of this era should be body colour.  Many people assume they are supposed to be black.  That is mostly because they are normally so caked with dirt and grime.   Some even get painted back due to that wrong information. It seemed like a good idea to remove the wheels and clean all the dirt and junk out.    I found a toilet brush (that hadn't been used in a toilet) with its long handle and plastic bristles good for this task.

I had done one of them before when I had to remove a wheel, so I only had three to do.  You can see why these cars rusted out in certain climates.  In both the front of rear there are so many places for dirt and mud to accumulate.  All you need is a bit of road salt for it to eat the car from the inside out.

For example, at the rear there is a sort of ridge or lip that allows a whole bucket full of dirt to get trapped up there. This can't be easily seen unless the wheel is off. Removing a stain from the boot lid I had noticed a stain on the boot lid of my car.  It looked like something had dripped onto the boot and then left a stain.  It was probably either some hard water that dripped from a parking lot, or perhaps bird droppings I had not removed fast enough. Given there were some swirl marks in other places on the car, I though it would be a good opportunity to give the whole car a bit of a polish.   I started by masking up the rear of the car, before getting out my polisher.

When I first bought my 1981 Mercedes 240D, the A/C did not work.  It was apparent that the car had been siting around for a while, so it was not really surprising.  What was surprising, was that it worked well when I had it gassed up.   When cars are advertised for sale as just needing a re-gas, you know that they need a lot more than that.   The gas had been retrofitted to R134A, as the caps were blue and red. The A/C worked well until I took the car off the road for a couple of months to fix the fuel system.  After that, the freon had leaked out again.  A further re-gas and having the valves changed basically just gave me my road trip to Brisbane.  Clearly there was a leak somewhere. I looked with my blacklight, and the issue was apparent.   There was green dye all over the compressor.   This isn't all that surprising.  A/C compressors need to be run regularly to prevent leaks.  As my car was likely laid up for a while before my ownership, the seals had obviously gone.

My 240D is new enough that it uses the GM 'pancake' style rotary compressor, not the York.  My 240D still had the AC Delco compressor with metric fittings these cars came with.  I do not believe these are available anymore.  I bought an Omega brand compressor to replace it with.  Naturally I had the drier replaced at the same time.

I could have stopped there but decided to upgrade the condenser too.   The original condensers designed for R12 don't work all that well with R134A.   I've been very happy with the Klima Design works condensers in my 560SEC and 450SLC so decided to also put one in the 240D. I noticed in the W123 instructions it mentions that you can paint the condenser black to match the factory look. I reached out to Klima Design Works to confirm that this would not impact cooling performance.   Their reply indicated that their testing hadn't seen any measurable impact.  I decided to paint mine before I had it fitted.

It was a pretty easy job to paint both the condenser plus the various fittings satin black.  I only painted the front of the condenser.    The back is not visible.

I had the new compressor, condenser, drier etc fitted a couple of weeks ago.   Painting it black made a huge difference in how noticeable it is.   I'll probably go back and see how much I can paint the condensers I have in the two 126s and the 107.

Its been pretty cold in Sydney since I got the car back.   The new upgraded A/C seems very good, but I've not had a hot day to test it with.  I'll be doing a trip in January for the 50 years of the W123 event, so having nice cold A/C will be a plus for that event.   While I don't miss most of the features of modern cars, I do very much appreciate cold A/C and these condensers really help.  I won't know until it gets hotter, but so far I am happy with my W123 air conditioning upgrade. While I don't particularly notice it when driving, it is apparent when the compressor kicks on when the car is idling.   The compressor is probably using a decent chunk of the power the OM616 makes at idle. It is a complete bolt in kit so I could go back to original at any time.  I don't plan to though. I have kept the original one to go with the car.

The prominent grille is one of the most obvious design features of the W123.  A scruffy grille can really let down the car.   On my 240D, the grille was in pretty good shape, but the plastic insert was starting to go chalky.  In addition, one of the clips that holds on the metal strips had broken and a previous owner had used hot glue to re-attach it. I had assumed I would just put up with it, as the grille inserts available from the usual parts suppliers in America are of horrific quality.   However, a friend who had recently purchased a 280CE mentioned that he got a very good insert from Niemoller in Germany.   I decided to order one, as well as a new auxiliary fan. When the replacement W123 grille insert arrived, I agreed with him.   Its not perfect but is quite good quality.   The only fault I could find in it is there is some slight evidence of where the plastic has flowed before it hardened.  You have to look quite close to see this.

Changing the W123 grille insert is not particularly difficult.  It is just one of those fiddly jobs that takes a bit longer than you expect it will.   To replace the insert, the entire grille must be removed.  This is quite easy as its held on by six 8mm screws. Four of the screws are quite obvious, but two require an extension and cannot be seen.  Once the grille is off the car, then the W123 grille insert is removed from the rear.  It is held on quite securely.  The two outer screws holding the grille shell to the car are also holding in the insert, so that leaves another six fasteners to remove.   The easiest one is the Philips head screw at the bottom.  Then the Mercedes emblem below the star also holds on the top centre of the insert and is removed with an 8mm nut.   That is also quite straightforward. The sides are more fiddly.  There are four clips that hold the insert flush against the grille shell.  The bottom ones hare hidden behind plastic spacers.  These are held on with phillips head screws.   Then, I removed the four clips by rocking them side to side with a flat head screwdriver until they came off.

With the insert removed, the metal strips can be simply slid off.   The horizontal ones slide outwards and the vertical one slides down.  Other than the one held on by hot glue, they were simple to remove and re-install on the new insert.   On closer inspection, my strips are not as good as I thought, and I regretted not getting new ones.  I'll try and polish them up with metal polish.   While I was there I also transferred over my grille badge.

Re-assembly is the opposite of removal.  While I was at it, I noticed that the blue surround of the Mercedes emblem was a bit faded.  I had a much better emblem on one of my spare W126 grilles, so I swapped it over.  Its not perfect, as some of the white paint on the star has come off, but its in quite good shape. There are also a couple of metal clips to accept the mounting screws in the top left and right corners of the insert that I swapped over to the new one.

The main thing I discovered while re-assembling the grille is that the Philips head screw at the bottom of the grille should be re-installed last. I tried putting it first.  However, there are some plastic tabs that sort of tuck into the grille shell inner rim.  If the bottom of the insert is secured first, they are not property tucked in and the insert doesn't sit correctly.   I found it better to install the Mercedes emblem first to locate the top part of the insert, and then the sides, then the bottom last.  The metal clips on the sides are the most fiddly, but eventually went on with a flat head screwdriver. Re-installing the grille was also a bit fiddly.   After a few attempts to line it up, I found it easier to use the two inner screws to locate the grille on the bonnet.  I inserted these with the bonnet in the normal position. From there, I installed the two outer screws.   For the middle ones, the bonnet needed to be in the service position.  Otherwise I couldn't put the screw on the end of the socket and then guide it into place.

I'm pretty happy with this improvement.   There are two other future improvements.  I will try and polish up the metal strips, and the star can be a bit limp at times.  On my trip to Queensland it would sometimes fall over at speeds over 100km/h.

Observant readers will notice I made a mistake.   I noticed it when writing up this article.   The tongue for the latching mechanism is not in the right spot.  While I had put it in place when first fitting the grille, when moving it around to fit, it must have fallen out. I went back the next day to check.  It took a few minutes, but I eventually got the bonnet open.  I was able to use a hook to pull the latch open without damaging the grille.  Since the grille is now screwed into place, It wasn't just a simple matter of putting the tongue in the slot.  At first, I thought I would have to remove the grille again, but then I noticed that the tongue is easily removable.

In about thirty seconds I had the circlip and pin off.  That then allowed me to re-install the tongue from the front and then re-attach it.

I recently noticed that the A/C on my 1981 240D wasn't cooling so well in heavy traffic.  On closer inspection, the W123 auxiliary fan was not kicking in at all.   This is supposed to kick in when refrigerant temperatures are high to blow air over the condenser. I had a quick look at the wiring diagram to start troubleshooting.  On the W123 diesel is a pretty simple system and easy to test.  There is the switch on the A/C receiver/drier that triggers a relay to run the fan.  Unlike the petrol cars, there is no trigger for high coolant temperature, the fan is only for the A/C. My first step was to jump this switch.  When I did so, I heard the relay click, but the fan did not come on.  Seemed apparent that my fan had died. While I was ordering a new W123 grille insert from Niemoller I also ordered a new fan. It would seem the Bosch fans are no longer available.  Swapping the fan over is not particularly difficult.   It is secured in three places.  On the bottom, there is a small phillips head screw that holds a piece of plastic trim in place.  This trim is a filler piece between the grille and the bumper bar.  That phillips head screw also locates a bracket at the bottom of the fan.  The fan is removed with the bracket attached, as the plasic trim can flex enough to let it past. The top left and right of the fan are held on with 8mm bolts with little brackets to the diagonal stay tubes.   Unplugging the fan is harder than removing it.  The plug is clipped onto the body of the car in a spot that is a bit hard to get to with the car on the ground.  My hoist is currently broken, but I eventually used a pick tool from the top to remove the clip and then I unplugged the fan from the bottom.

When I removed it, it was amazing how much debris was caught underneath the fan.   I cleaned this up as best as I could.  It was a simple matter to transfer the bottom bracket from the old fan to the new fan.  I was also hoping to re-use the plastic finger guard. However the body of this new fan is quite different and is not compatible.   Given the incompatibility, I think this fan should have come with a finger guard that fits.

Re-installation was a bit fiddly, The bottom mount is easy to fit, but it took some time to get the two side mounts to line up properly.  It was also a bit of a pain to get the plug clipped back in place.   In the end I did, and the fan whirred into life when I jumped the switch on the receiver/drier.

W123 instrument clusters are notorious for jumpy temperature and fuel gauges and mine was no different.  This problem seems to impact other Benzes of the era, but is particularly pronounced in the W123. I don't really like not being able to trust my gauges to be generally correct, so I wanted to see what I could do about this.   The issue seems to be mostly due to grounding.  The whole cluster gets ground from one plug, which then provides ground to each of the instruments, and lights. A friend of mine with a W123 had fixed a cracked solder joint in his cluster that had made a big difference.  I'm terrible at soldering, so he offered to take a look at my cluster and see if the same solder joint needed repair. Last week I removed my instrument cluster.  On removal, it had obviously been out before.  Somebody had written an odometer reading on the back, which I assume was done when the odometer was previously repaired.   The cluster was generally in very good shape, except somebody had tried to pull it out from the front before and slightly damaged the front cover, so I had to be careful. I find the easiest way to remove these clusters is to remove the drivers side speaker and push it out from behind.  The W123 instrument cluster is harder than the W126 version, because the oil pressure sender is mechanical.  For reasons only known to them, Mercedes-Benz give you almost no slack to play with on the oil pressure line and speedo cable.  Even an extra two to three centimeters would make a big difference. A 10mm spanner is needed for the oil pressure line, but the rest of the connections can be done by hand. My friend looked at my cluster, and didn't see the same solder joint broken.  There was some oil inside the cluster, and some of the screws were a bit loose.  Since the oil pressure gauge does not seem to be leaking now, I wonder if it leaked in the past?   Regardless he gave it a clean and also made sure it was screwed in properly.  From what I understand, the screws are important for the grounds.

I also decided to add another ground line.   From reading on the forums, it seems a lot of other W123 owners do this.   I figured it couldn't hurt.  I grabbed a couple of ground lines with eye terminal from the 420SEL parts car. One terminal went on the other side of the ground bolt behind the W123 instrument cluster, held it on with a washer and nut, also from the 420SEL.  I put the other ring terminal behind one of the screws on the instrument cluster.   The only non Mercedes part was a connector between the two ground lines.

My 1981 240D was sold new with a Becker Europa 596 Cassette. The Becker was still in the car when I purchased it, but it would not stay tuned. It would randomly drift out of tune and need constant adjustment.   I found that rather annoying, I removed it to be serviced and put in a Europa II temporarily.  A friend in the Mercedes club was able to help me get the radio serviced.  It is now working well. I got the radio back last year, and finally found time to re-install it.    I had also seen on Instagram where anther W123 owner had installed a USB charge port meant for an E36 BMW in place of the factory fader.    My factory fader is still working, but my 240D has two switch blanks on the top console, which is the perfect spot for a charge port.   The USB charge port was quite expensive, but it looked like a really good solution so I ordered one. To power the Becker 596, I also planned to install another Tranzit BLU Bluetooth Box.   This is the same solution I have used in my 560SEC, 300TE and 450SLC.   I'm very happy with it.   The Tranzit BLU is a small box, about the size of a deck of playing cards that provides a FM signal directly on the antenna wire.   This makes it far less susceptible to interference.  It also provides a handsfree option for calls.

Normally the Tranzit BLU is controlled by a hidden button.  However, I had the idea of using a factory sunroof switch in the other blank switch location instead.   I didn't have a W123 sunroof switch in my box of parts, but I had one for a W116 or W107, which is good enough to test with. The installation was pretty simple.  I use the connector for the cigarette lighter to power the USB charge port.   The spade connectors that came with the charge port were too narrow, and not quite long enough so I made some extensions.   In testing the USB charge port, I was also able to easily pull off one of its connectors, so I crimped on a new one. Since the USB charge port is designed to be added to an E36 BMW, it has been designed to piggy back off another accessory.   Therefore, it already had power and ground connectors for the Tranzit BLU.   I used a relay to trigger the Tranzit BLU from the Becker Antenna trigger.   That relay then powers the Tranzit BLU and also triggers the power antenna. Instead of the button that comes with the Tranzit BLU, I wired in the sunroof switch.  I used a multimeter to work out which of the four pins are activated when the switch is pressed forward.   Essentially the way the switch works, is when it is pressed, it joins power to one side of the motor, and ground to the other side.   Thus, pressing the switch the other way reverses these connections, allowing the motor to run in reverse.   I assumed for this purpose I just needed to make the connection to trigger the Tranzit BLU.  Turns out I was wrong.

I wired it all up and did a quick test of the system.   I was able to pair my phone and play music through the Becker 596.  However, the switch did not work.   I tried a few more pin options to no avail.   I had assumed that the switch was 'dumb' and just made a connection to trigger a press of the button.  However, it was looking like that was not the case.   I got the Tranzit BLU switch and connected that to a multimeter.   On very high resistance settings, I was able to trigger a change in resistance when pressing the button, but it wasn't constant.    Given there appeared to be more to this button than I anticipated, I gave up and put the switch blank back in place.    The Tranzit BLU button is now on the steering column out of sight like in my other cars.

Despite the failure of using the sunroof switch to power the Tranzit BLU, I am very happy with the setup.   The correct Becker is back where it should be and I can play music through my phone and make and receive phone calls.    I am taking the 240D on its first road trip this weekend, so having music will be great.   The install is totally reversible with no factory wires cut.

Back in September, when I started to deal with the algae problem in my 240D, I noticed the car was quite hard to push.   At that time I tested to see if the brakes were grabbing and it was clearly the fronts that were to blame.  The rear wheels spun freely ever after a hard push on the brake pedal. Since I had the car in the air, I used the time to check what calipers I had on the car.   On the front, I had Bendix and on the back I had Girling.   Once I dealt with the fuel delivery issues, I planned to have the brakes sorted out.