| I have been in the process of installing a Becker Grand Prix 1402 in my 1990 300TE. This is the model of radio it came with, although this particular radio is not original to this car. In the first installment, I sourced and tested the Becker 1402 and removed the Sony Xplod. In part two, I wired in the right connectors for the Becker, as well as the iSimple Tranzit BLU HF FM injector. By the end of that installment, I had music from my phone playing through the speakers of the car. To complete the install of the Becker 1402, my first step was to tidy up the wiring. This was primarily using cable ties and electrical tape to create separate harnesses – i.e. for power, for speakers etc. I also attached the relay to the power harness so it would not get stuck or jammed when the radio came in and out. From there, it was trial fitting the radio to make sure everything still worked. Unlike modern radios with a DIN frame, the Becker just slides in. I also took the time to make sure the USB charging ports worked – something I had not done on the 560SEC install and regretted.  Once I had the radio in, it was apparent that the wood trim needs to be installed first. I therefore removed the radio to complete this task. As an added benefit, I was hoping to improve the alignment of the wood trim while I was there. I had noticed the small ‘feet’ in the upper switch frame were not flush with the console. As one of the mounting points on my car was broken, it took a bit of moving around, but eventually I had it aligned properly.
It didn’t seem to help much as the wood trim is still not all that well aligned. I’m not 100% sure why – possibly because this wood trim is not original to the car, or possibly due to various radio and other work on the car something is misaligned.  The wood trim is quite easy to install. It hooks onto the top, then the combination of a pair of screws above the radio, and some large but thin nuts around the A/C control knobs hold it in place. A large socket with a knurled thumbscrew was a good way of making sure I didn’t overtighten.
 At this point I also verified that the hazard lights were still working. From there it was re-installing the radio and testing it to make sure all the connections were good. They were.
Next was re-installation of the ashtray assembly. This is held in with two screws. The main issue here is making sure the wiring harness for the cigarette lighter is sitting properly so the ashtray can still open and close. Like with the 560SEC, I situated the control button for the iSimple Tranzit BLU on the side of the console, as well as the mic for the handsfree kit. It has worked quite well on the 560SEC. The radio is now in and working and I really like he way it looks in the dash. I have handsfree calling, as well as music control from my phone. I personally think there is a lot to be said about using a period correct radio in a classic car. Sure, it won’t sound as good as a modern radio, but it fits so well in the dash, and they work really well. They are part of that simplicity that classic cars have which is lost in moderns. I can operate all functions I need without taking my eyes of the road. Few modern cars can say that. 
Yesterday, I started installing a Becker 1402 in my 1990 300TE. This was the radio it was sold with, and the same radio I have in my 1987 560SEC. I had removed the old Sony and inspected the wires, plus fixed my broken Hazard light switch. This morning I looked up the wiring colours for the Sony online. The wiring in the car has been ‘modified’ by various radio installers over the years, so starting with the Sony wires was a good place to start. As outlined the operation instructions, the Becker 1402 wiring harness has four wires going into the custom plug. These are: Ground, Switched Power, Illumination & Constant power. Before I wired in the Becker harness, I also needed to provide some connections for other accessories. I wanted to add in USB charging ports and the iTranzit BLU FM injector. As the Becker will use a lot less power than the modern Sony, I wasn’t too worried about the power draw. My new setup should use less power overall than the old one. I’m already charging my phone from the cigarette lighter which comes off the same circuit. I planned to let the Becker 1402’s antenna trigger turn on the iTranzit BLU, using a relay. This is the same setup I used on the 560EC. The iTranzit BLU uses very little power, but I didn’t want to chance overloading it. Thus, the antenna trigger is connected to a rely, which in turn turns on the power for both the iTranzit BLU and the power antenna. From the ground wire, I needed connections for the Becker, the iTranzit BLU, the relay and the USB ports. For the Switched power, I needed a wire for the Becker and one for the USB charging ports. The illumination just went into the Becker, but the Constant power was needed for both the Becker and the relay. As I wired the Becker connectors in, I just added a few additional wires for these other accessories. 
There was a very handy spot in front of the shift lever assembly that was a good fit for the iTranzit BLU. This was close enough to the Becker 1402 for the antenna connections, and out of the way. At least on the W126, this is where a control box for the airbag goes, should the car be so equipped. It’s probably the same on the W124. I was able to push its wires up behind the ashtray. The control button will go out the side of the centre console, as will the handsfree microphone. The relay that powers it will just be taped to the back of the Becker. To get the USB plugs out a small gap between the carpet and the centre console, I taped them to a now removed mobile phone connector, so I could pull them through. As mentioned above, this just wired into switched power, as I didn’t want a small current draw when the car was not being used. 
I was now ready to do my first power on test. Before I started with the speaker wires, I plugged in the factory Becker plugs that were still floating around in behind the radio. As expected, they did nothing and are no longer in use. On the other hand I had no other issues with my wiring. The Becker 1402 powered up as it should. It accepted the security code. The relay trigged both the antenna and the iTranzit BLU. The illumination worked as it should. After this test I cut off the now disconnected Becker speaker plugs, as I wanted to use them for the radio. Since the Becker is a 2x25W radio, I needed to splice both left speakers together and both right speakers together. I don’t plan to re-wire the fader. This is the same setup I used when installing the Becker in a friend’s 450SE recently. Essentially the left front positive is joined up to the left rear positive, and the left front negative to the left rear negative. The same goes for the right side. Before I did this, I first checked the speaker wires were correct. This can be done with an AA battery. Simply hold the positive wire to the top, and the negative wire to the bottom, and the speaker should make some static. Its a quick and simple way to check the speaker wires are as you thought. Its only 1.5 volts, so the wires can be held on by hand. All four speakers worked, including the front left that hadn’t been working before. Probably a connection issue to the Sony. 
Once I had the speaker wires connected properly, it was time to plug them into the back of the Becker 1402 and test the sound. It sounded great. Perhaps some confirmation bias, but much better than the more modern Sony. Both AM and FM worked well. On the other hand, the iTranzit BLU wasn’t playing music as I thought it should. On closer examination of its manual, the status light was blinking three times. This means its connected, but needs resetting. Holding the action button down for six seconds took care of that. Soon I had Sherbet’s Howzat playing through the speakers of the 300TE! This was a good place to stop. Everything seemed to be working quite well. My task next time is to tidy up the wiring and actually put the Becker 1402 into the dash where it belongs. I purchased my 1990 Mercedes 300TE with a modern Sony Xplod CD player. It was a fairly low end model that sounded pretty bad and looks really out of place in the W124 dash. The passengers front speaker was not working, adding to the poor sound. The S124 has very silly speakers in the rear, one of the few design flaws in the vehicle. Losing one of the front speakers is a major blow to sound in the car. My car was first sold with a Becker Grand Prix 1402. The operating instructions is still in the owner manual kit. This is the same Becker I installed in my 1987 560SEC. I’ve been really happy with the setup in that car. My plan was to install something similar in the 300TE, but without the external amplifier. The speakers in the 300TE are quite small and I don’t think the additional amplifier is necessary. I will be using the Bluetooth FM injector, just like on the 560SEC. The first step was to find a W124 Becker radio. I have been keeping an eye out since I bought the car. In the end I found a radio that had been purchased by a friend in the Mercedes Club for his W126. In the end he preferred something a bit more modern, but still with a classic look. As that radio was surplus to requirements, I purchased it for my 300TE. He had the radio refurbished a few years ago, so it tested fine. 
For a W124 Becker radio install, a set of the plugs for the rear of the radio is also required. Luckily, I managed to secure a set from the parts car in Las Vegas last year. My next step was to remove the old Sony from the car. The previous owner had left the DIN tools for the radio, so I was able to get it removed fairly easily. On removing the old radio, I was quite shocked to see a set of plugs for a subwoofer in the back of the Sony. I was very confident that there wasn’t a subwoofer installed in the car, let alone a working subwoofer. 
It wasn’t clear where those cables went. before I went any further, I needed to trace them and see. I didn’t want to leave a rats nest of old cables in the car, if I could avoid it. I first removed the ashtray and the centre console wood. They didn’t disappear into there. They seemed to go to the left, so I started pulling up the carpets on the passengers side of the car. Sure enough, I found the cables cut off in the passengers side foot well. I guess a previous owner had a subwoofer installed at some point. The installer of the Sony Xplod just didn’t bother to trace the cables, and just plugged them into the back of it. I’ve now removed them. I also saw the remains of an early 2000s phone charger in the centre console, so will need to trace that and remove it too. After that, I got to looking at how the Xplod was wired in. There is little trace of the old Becker plugs for the radio, but there are some remains of the speaker cables. They were not connected to anything, so I don’t think they are in use anymore. The connectors will be quite useful to me regardless. For my W124 Becker install, I needed to verify the purpose of each wire in the back of the Sony. The Sony manual didn’t include any information on that, just useless info about not scratching your CDs. 
I’ll do some research on the internet to get the wiring info for the Sony, so I can wire in the Becker plug next. While I was there, I also wanted to swap out the hazard light switch. It was jammed in the off position and didn’t work at all. I removed the upper wood trim to get to those switches. To remove it, there were two small screws at the bottom, above the radio. Then the two large knobs hold it on.  From there, the frame around the switches can be removed with a Philips head screwdriver. Once that frame is removed, the switches just pull off. I had a spare hazard light switch in my box of Mercedes switches, so I was able to quickly swap it over, and successfully test it’s operation.
 In the next step of my W124 Becker radio install, I want to sort out the plugs for the Becker radio – i.e. the speaker plugs and the power plug. That will allow me to test the radio in the car. Then I can install the FM injector. I’m taking the car on a short road trip at the end of the month, so my goal is to get it done before then.
Since purchasing my 300TE, I haven’t been happy with the operating temperature. It hasn’t overheated, but it was running hotter on days in the mid to high 20s than I would like to see it. I want to be able to rely on the car on days well into the 40C range. My mechanic had suggested that the fan clutch be changed. I had that done, and while there was an improvement, I still didn’t like what I was seeing. I was hearing the fan clutch roaring while cruising on the motorway, and temperature was creeping up at motorway speeds. Lowest temperature seemed around 80km/h. I figured the next place to start was the 300TE thermostat. They are wear items and I figured it made sense to make sure I had a new one in place before I started looking too hard at other aspects of the cooling system. I thought that perhaps the 300TE thermostat was not opening all the way. In addition, while I was at it, I wanted to replace the coolant level sender. The light would sometimes come on, or start to glow dimly even though the level was fine. I started by using a large syringe to drain out as much as the coolant as I could. Better this than let it run out onto the floor. 
This is not a hard job, if you have the right tools. I have a set of circlip pliers, which make changing this sensor very simple. I spent an hour looking for them and can’t find them anywhere. Tring to get this off with a normal set of needle nose pliers took almost as long. I also managed to break one of the wires off the terminals when removing it. I’m going to have to repair this before I can actually use the new sensor. A job for another day. 
Back to the thermostat – I had a couple of new thermostats in my parts stash, so went with a 80C Wahler thermostat. Wahler thermostats have the best reputation for actually opening at their rated temperature. Some of the other brands open a few degrees hotter than their rated temperature. I also find that R134A A/C performance starts to taper off when the coolant temperature is on the higher side. Not sure why this is, perhaps the condenser’s proximity to the radiator? The old 300TE Thermostat was also a Wahler, but it was an 87C. This is the factory rating – I just prefer 80C for the Australian climate. It broke when I was removing it, so I couldn’t test it to see if I was opening fully.  Before I removed the thermostat, I snapped the photo above. Not just for this site, but also to record the orientation. The jiggle valve is supposed to be at the highest point in the housing to prevent air pockets. As the M103 housing is almost horizontal, the photo was a quick way to ensure I put the new one in properly.
Unfortunately for me, the air bubble looked like the jiggle valve on the small phone screen, so I installed the new 300TE thermostat with valve in the wrong spot. I didn’t notice until the day after as I was about to write an article for this site, and saw the photo on the computer screen.  Since I didn’t know the thermostat was not installed properly, I went ahead with using the bleed valve on top of the thermostat housing to remove air bubbles and running the car up to operating temperature. Despite the jiggle valve being in the wrong spot, the temperature didn’t move above 80C in the driveway, even with A/C on max. Note the photo above has the thermostat the wrong way. It is there to illustrate the wrong way to do things.
Today I went back and did the job again. As the thermostat housing is fairly level, not sure it had a big impact, but I like to do things properly if I can. Again, idling in the driveway, I wasn’t able to get the temperature to move over 80C. I didn’t take the car for a drive, as I only have 60 days per year to drive the car, and it seemed a waste of a day in the logbook for a short test drive. I want to take it out on the motorway and make sure its sitting at 80C at 110km/h. Today I attended the monthly Machines and Macchiatos event in Terrey Hills. Last time I was able to attend was October 2022, when I took my DS. Today is a swelteringly hot day of almost 35C, much more suitable for a car with air conditioning. I don’t think I’ve taken my 250SE to one of these events before, so I brought it along. There was only one other classic Mercedes – a very nice 280SL pagoda in a subtle two tone. I’m not sure if the heat had something to do with it, but the numbers were down quite a bit from previous events. There are two main parking areas that are used, and previously both have been pretty full. This time there were only a handful of cars in the second one. It was interesting to contrast the 280SL Pagoda with a Series 2 E-Type OTS. The production years almost fully overlap between the 280SL and the Series 2. While the Series 2 is not considered to be the most desirable E-Type, the 280SL is thought by most to be the most desirable Pagoda. I actually prefer to the earlier cars, but am in the minority. 
At least at the time I was buying my E-Type, a Pagoda would have been another option. And given I’ve always been into Classic Mercedes a good one. I probably could have purchased a nice left hand drive Pagoda for the same price too. I did think about it, as well as Porsche 356. In the end I went with the Series 1 E-Type because I think its the better classic. The Pagoda is much better made, and probably more reliable and a better choice for regular use. However, the Jaguar is more advanced, with the DOHC six and proper independent rear suspension. It’s far more powerful and has a better manual gearbox. They are both fairly cramped for me. The Pagoda also drives a lot like its bigger brother, the W111 coupe, which I prefer. The E-type is sportier and a better contrast with the other cars I own. Plus, only the very early USA models were not spoiled by horrible side marker lights and other USA mandated nonsense. Having said all that, they are both great cars and I would have been happy with both. I really liked the colour of both cars. The 280SL Pagoda had a lovely contrast with the body and the hard top, although strictly speaking the hubcaps should be the same colour as the hard top. The red interior is superb. The E-Type looked great in that deep red with the black interior. While the numbers were down, there were a fair number of interesting cars on display, particularly classic Holdens and American cars. Today I joined the MBCNSW for a drive to the Australian Motorlife Museum. The museum is located in Kembla Grange, near Dapto. It primarily focuses on pre war cars, motorbikes and automotive memorabilia and there are over 100 vehicles on display. I had previous visited the museum in 2018. I was looking forward to a return visit as the collection does change, and there is so much to see you’ll always find something new to look at. The treasurer of the MBCNSW is a board member of the Museum, so he organized a guided tour of the museum. That was a huge bonus from my previous visit. Not only did we get more background on some of the displays, but we also got to tour the behind the scenes workshop and the library. The museum believe their library to be the largest automotive library in the southern hemisphere. I could believe it, as it is quite large. We also got to sit in the back of a very impressive Lanchester and hear the story about the pair of Minervas. This is a high end car, based in Belgium. Apparently these cars were the properly of Prince Leopold of Belgium. The more ornate car being the official car, and the other being for daily use. 
The other thing you notice is just how much automotive memorabilia they have on display. There must be literally thousands of great pieces. I took my 250SE on the drive. I was keen to take it on a longer drive with its newly fitted alternator. The car did really well. It was a 35C day, and the A/C kept up with the heat pretty well. The cooling system on that car is really good – it hardly moved off normal operating temperature. I had by far the oldest car that wasn’t in the museum. The next oldest was one of the three W126 models – always popular in the club. Compared to the museum cars, my car was a spring chicken. Last time I visited, I drove down in the 1954 Citroen Traction Avant I used to own. It was still quite a bit too new for the museum. After our tour around the Motorlife Museum, we took in a pub lunch at Kembla Grange before the drive home to Sydney. This last week my 250SE has been at the workshop having an alternator upgrade. Back in 2020, my alternator gave up, and I replaced it with a rebuilt 35A alternator. Ever since then, that alternator has struggled to charge the car. It would charge the battery when driving along during the day, without any accessories. But as soon as the A/C was running or the headlights were on, it would barely make enough power. The charge warning light would come on at idle, and even faintly glow when driving. The W111 alternator is supposed to be a 35A model, and the previous alternator had a 35A part number. It kept up much better. I can only assume that either the previous alternator was rebuilt at some point to make more power, or the new one wasn’t a good rebuild and was making less power than it should. I had already replaced the external voltage regulator to rule this out. That W111 alternator barely being able to keep up with the car’s power needs made me reluctant to take the car on long trips. I also wondered if it had anything to do with the car’s recent running issues. With the charge warning light on, was it even making enough power at idle for a strong spark? 
I decided to source a better alternator, and purchased a Bosch rebuilt unit from the USA. Instead of going with the standard w111 alternator of 35A, I went with a 55A alternator. This is a bolt in replacement that still uses an external voltage regulator. The one I went with is used on the late 280S/SE W108 and the /8 models. Other than a slightly different plug, you would hardly notice the difference. I didn’t want to change the wiring to go with an internally regulated alternator. The Bosch rebuilt units have a good reputation, and this W111 alternator looked almost new.  As can be seen in the picture, the rebuilt alternator didn’t come with a pulley. When my mechanic was removing the pulley off the previous alternator, he discovered that it wasn’t assembled properly. They had used the wrong pulley, and to make it fit, omitted the little key that prevents it from spinning on the shaft. It had been tightened up, so wasn’t obviously slipping, but who knows what was happening under load? My mechanic had another dead alternator with a good pulley he was able to use.
In any case, there was a huge difference in performance with the new W111 alternator. Even with headlights on high beam, AC on max, I was still getting just under 13 volts at idle. It would drop down into the high 11s before at times. The one thing that it did not improve which I was hoping was the radio performance. I’ve been having all sorts of strange behaviour with my radio. I event sent it back to the seller to test and it worked fine on the bench. I was hoping that a better and more consistent power supply might fix these issues, but it hasn’t. More investigation to do there. As well as the W111 alternator, the car also had a regular service and a tune. Previously the idle was very low and it would be almost stalling in gear. Now its driving really nicely – better than it has in a couple of years. Its a really nice car to drive again. While it was in the workshop, I also had the subframe mounts checked. The front end feel is a little vague. The subframe mounts made a big difference on my 450SLC. The verdict was they were fine. 
The sunroof on my 280SE has not worked properly since I bought the car. It would sometimes move a bit, if I played with the switch, but not often. Since I didn’t want the roof stuck open, I didn’t use it. Based on that, I figured my issue was the W116 sunroof switch. The car is booked in for the Shannons auction in May, so I wanted to get the Sunroof working. I don’t use sunroofs a great deal, but they are not common on the W126 280, so its a valuable feature on my car to be working. I had sourced what I thought was the right switch, so I figured a simple matter of just fitting it. Removing the old switch was somewhat of a pain, as one of the tabs that holds the switch in place was bent out too far. In the end I got it out, and promptly lost the plug in behind the dash. I was able to reach it again by removing the demister switch and using a hook tool.  This was also required to get a finger in behind the plug, so push the switch on. Straightaway, I had a problem. The new switch was reversed from the old one. I could open the roof with the close side of the switch, but not close it. I’ll have to compare it, but I may have a C107 switch.
At that point, I figured I would have to persevere with my old switch. I gently took it apart and found it quite dirty inside. The old grease had become quite sticky. The switch is quite simple, it pivots on two very small ball bearings, and pushing down makes a contact with a metal bridge and the body of the switch. I didn’t take a photo as I didn’t want to drop the small parts out of the W116 sunroof switch. I used some brake cleaner to clean the parts up. Quite a lot of dirty gunk came out of the switch. I didn’t re apply grease, as I didn’t have one suitable for electrical connections. Once I plugged it all back in, the sunroof finally worked. While I was there, I also wanted to fit the new SLS control rod that had arrived in the mail. The old one had broken bushings and I temporarily held it on with some cable ties. That hadn’t worked, as only the very inner pin of the each end of the rod was still present! I’ve already covered setting the proper ride height of this system. The system on the 280SE was working perfectly as the arm changed the ride height as it should. Finally, there was some minor rust around a door drain hole. I treated it with rust converter and painted it, to ensure it didn’t get any bigger. Unusually for a W116, as far as I can tell this is pretty much a rust free car. I didn’t want that to change. 
Earlier this year, I had the suspension spheres on my 1970 Citroen DS checked for pressure. The ride had become pretty terrible, so it was obvious there was a problem. We were able to successfully regas the fronts, but one of the rears was completely dead. It was time for some rebuilt rear spheres. My mechanic sent them away to Pleiadies in Queensland. They were able to fully rebuild my rear spheres including new diaphragms, and repaint them to the factory colour and pattern. When they arrived back they looked almost too good to put on the car!  A bit of a contrast to my front spheres. It would only be a few years later that Citroen went to the disposable spheres. That seems a shame, as the rebuildable spheres are still going strong 50 years later.
Fitting them is pretty straightforward, and my Mechanic had them on in a few minutes.  A quick top up of LHM later, and the DS was back to its original ride quality. The ride is such an integral part of these cars.
The next day I took the car for a drive and confirmed everything is working properly. The ride is back to its previous quality, and its a nice car to drive again. The rebuilt rear spheres are doing their job well. Since I was out on the road in the car, my Mercedes mechanic has always been interested in seeing the car, as his father had a couple of DS models in the 60s and 70s before switching to Mercedes. I probably get more positive comments about the DS from people than any other car I own. 
Of course the only downside of a drive on a Saturday morning is all the hyper aggressive cyclists. It seems once they put that lycra on, the rage builds inside. Sometimes I think they ride like they are trying to get hit, just to prove a point. Really not sure the point of cutting off cars and trying to block them on a bicycle. When I first got my 300TE registered, I had the A/C regassed as it wasn’t very cold. That made a huge difference as after that the car was ice cold. According to the service history, it had been a couple of years since it was last done, so it was probably about due. At the time, my mechanic suggested I replace the fan clutch, as the electric fan was cutting in quite a lot. He didn’t think the mechanical one was getting enough air through the condenser. I figured this was a good idea, because even on a warm (e.g. 28c) day, the car would run a bit over 100C. Nothing wrong with that temperature, but I want to to be able to confidently drive the car with the A/C on in 40C weather, and that doesn’t leave a massive margin. I looked into the fan clutches, and while there were cheap ones available for very little money, I had no confidence they would last very long. A genuine Mercedes-Benz W124 fan clutch from the classic centre was about the same price as Behr clutch from Pelican Parts. I also wanted to order a new ignition tumbler from the classic centere, so this would combine shipping. The part number for my W124 fan clutch was 103-200-04-22. On closer inspection, it was made by Behr.  There is a special tool required to lock in the water pump to remove the W124 fan clutch. I don’t have this tool, plus I already wanted to take the car to the Mechanic to replace the brake hoses and do a fluid flush. It wasn’t clear when this was last done from the service history. I wasn’t sure of the age of the hoses, the the fluid really should be flushed regularly.
I also didn’t think the brake pedal feel was quite as good as I was expecting, so it was an opportunity to check the pads too. Turns out they were fine, so at least I have a spare set on hand. Before I sent the car in, I noticed the rubber grommets on top of the brake fluid reservoir were quite old and cracked. These had prevented me from using a vacuum bleeder on the W126, so I swapped them out. For some reason, the brake fluid light is now always on. I’ll have to check them and make sure I put them on properly. The other thing I wanted to do myself, was make sure the coolant level was correct. The reservoir was filled right to the top even cold. I assume that when the car gets quite hot it would place undue strain on the cooling system. To be safe, I removed some coolant to get the reservoir to the right level when cold.  I had also wondered if this extra pressure might be why the low coolant light went on after the car warmed up. Turns out, its not, and my next step is to change out the sender unit.
After all this, what were the results of my W124 fan clutch replacement? The car was better, but not as good as I hoped. Running temperature was a little lower (just under 100) and the electric fan didn’t cycle quite as much. The most concerning thing, is that the temperature was at its best at about 70-80km/h. It actually went up at 110km/h. I could also hear the fan clutch roaring at constant freeway speed, which it shouldn’t. My next step will be to change the thermostat. I have spares on hand. Plus, Its a cheap and easy fix before I start to worry about things like radiators and water pumps. Not sure what is in the car, but I plan to use an 80C thermostat. I think 87C may have been standard, but I prefer 80. I find A/C performance with R134A starts to degrade when the coolant temperature is above 90C. | |
