Instruments and switches (54)

Drawing of MB 219 instrument panel, © Daimler AG

Drawing of the instrument panel for the Mercedes-Benz type 219, © Daimler AG

Combi instrument

Disassembly and restoration of the individual parts

The instruments were in a decent shape but as usual I tried to aim for a “like-new” state with all parts of the instrument cluster or as it is called in Mercedes Ponton-language, combi instrument.

First the front of the cluster was removed from the cluster itself. As you can see in the third picture above, the old grey vinyl was dirty, discolored and in an overall bad shape, both from usage and also due to the storage and handling during the restoration.

  • Ponton combi instrument front is unscrewed
  • Rear side of combi instrument front
  • Front side of combi instrument front

After that the chrome frame went off. Underneath it you have three sealings. After that you peel off the instrument glass. As you can see there are a couple of rubber sealings glued into the frame, probably for vibration dampening for the glass. From Ka-Ja TachodienstKa-Ja Tachodienst I got a new set of rubber.

Since the chrome frame had some pits and cuts it was sent for re-chroming together with the clock’s frame. 

  • Chrome frame off, sealing is behind
  • Peeling off the instrument glass of a Mercedes-Benz 219 combi instrument
  • Rear side of Ponton instrument cluster chrome frame with rubber sealing, probably vibration dampening
  • Where the rubber sealing in the chrome frame was glued

The we have a couple of pictures that show how the vinyl is glued onto the frame.

  • Top side of front
  • Bottom of front
  • Right side of front
  • Left side of front
  • Rear side of front

For protection and a clean surface for the new Roser red vinyl, the front was brushed and repainted. As you may understand that paint will not be visible. 

  • Front cleaned and brushed
  • Combi instrument front being painted
  • Combi instrument front painted,ready for new roser red vinyl

When it comes to the disassembly of the base plate, be careful when you remove the foam rubber profile that is glued onto it and which seals against the front of the combi instrument. Don't "drag" it off the plate because then it will end up like mine, two sizes too big (see below) or you may brake it. I haven't been able to find a replacement. Next step was to remove the old lamps, cables and different instruments from the base plate.

  • Disassembly of combi instrument base, its instrument, lamps, cables etc
  • Disassembly of combi instrument base, its instrument, lamps, cables etc
  • Disassembly of combi instrument base, its instrument, lamps, cables etc
  • Disassembly of combi instrument base, its instrument, lamps, cables etc
  • Disassembly of combi instrument base, its instrument, lamps, cables etc

The front of a Mercedes-Benz 219 Ponton combi instrument and the parts that were restored by Ka-Ja Tachodienst

The front and the parts that were restored by Ka-Ja Tachodienst

The first picture below shows the old water temperature gauge and sensor and the second the restored. Ka-Ja Tachodienst did a complete overhaul incl replacing the capillary tube and tested the complete unit.

  • Unrestored water temperatur gauge and capilar tube
  • Restored and tested Ponton water temperatur gauge and new capilar tube

The first two pictures show you the original status and the third the restored and tested oil pressure gauge.

  • Unrestored oil pressure gauge
  • Unrestored oil pressure gauge
  • Restored and tested oil pressure gauge

The first and the sixth picture show the disassembly of the speedometers base plates. The fifth shows the wear on the gearwheels and finally you have the repaired and tested speedometer.

  • First part of removing speedometer from base
  • Speedometer
  • Speedometer
  • Speedometer
  • Wear on MB219 speedometer
  • Second part of removing speedometer from base
  • Repaired and tested Ponton speedometer

The Ponton fuel gauge consists of two parts, the fuel gauge itself as well as the fuel sending unit that is mounted in the tank. Both units were restored and tested together.

  • Original fuel gauge and fuel sending unit
  • Original fuel sending unit
  • Restored and tested Ponton fuel gauge
  • Restored and tested Ponton fuel sending unit
  • Restored and tested Ponton fuel sending unit
  • Restored and tested Ponton fuel sending unit

Finally, we have the lamp cluster in the Ponton combi instrument containing control lights for the blinker, choke control and main beam light. This one I handled myself. First the cluster was desoldered from the base plate. Then the front was removed and the small net and the colored plastic tabs were carefully cleaned. New lamps were installed, Osram 3796 12V 2W. Done!

  • Base and lamp cluster in the Ponton combi instrument containing control lights for the blinker, choke control and upper beam light
  • Removal of Ponton lamp cluster
  • Removal of lamp cluster
  • Removed lamp cluster
  • Front, net, plastic tabs and base of Ponton lamp cluster cleaned
  • Ponton lamp cluster with new bulbs, Osram 3796 12V 2W

Assembly

First the lamp cluster was mounted and its related cables soldered. Then I started to mount the different instruments. See to that you align them correctly. This can be done in two ways; when you mount the instruments onto the base plate and/or by carefully loosening the screws that holds the instruments' fronts.

As mentioned above, be careful when you remove the foam rubber profile that is glued onto the base plate. Don't "drag" it off the plate because then it will end up like mine, two sizes too big (see picture). It was a bit problematic to "compress" the profile and glue it back. Doesn't look perfect but it seals against the front of the combi instrument as it should.

  • Lamp cluster soldered
  • Water temperature and oil pressure gauges mounted
  • Water temperature and oil pressure gauges mounted and aligned
  • Fuel gauge and lamp cluster mounted
  • Fuel gauge and lamp cluster mounted and aligned
  • Over-sized foam rubber profile for Ponton combi instrument
  • Foam rubber profile glued to Mercedes-Benz Ponton combi instrument base plate

Testing the fuel gauge

After the assembly of the instrument cluster I decided to test the fuel gauge and the corresponding fuel sending unit (or "Electric transmitter for fuel indication" as it is called in the spare parts catalog). The workshop manual gives you all the necessary values for this test. Would be a walk in a part. Right…

Excerpts from Mercedes-Benz Ponton Workshop manual regarding testing of fuel gauge

Excerpts from Mercedes-Benz Ponton Workshop manual regarding testing of fuel gauge

First, I tested the fuel sending unit. I choose to test if it gave the correct Ohm-values for full, half full and almost empty tank. With the battery and instrument cluster disconnected you measure the resistance between ground and the contact labeled “G” (in the pictures below it looks as if battery and instrument is connected, that is not the case). I mounted the unit in a stand for a micrometer and positioned it according to the instructions in the workshop manual. With the help of two pieces of cardboard, cut to prescribed height for "full" and "half full", and a good-looking nut, with the height of an "almost empty" tank, placed under the plastic float I could measure the resistance given by the unit’s internal coil.

  • Setting up the test stand for a Ponton fuel sending unit
  • Testing the fuel sending unit for full tank
  • Testing the Ponton fuel sending unit for half tank

Problem with the "evil eye" and my tries to remedy it

The Ohm-measurements were on the spot. Next, I connected the fuel sending unit to the fuel gauge’s via the instrument cluster’s cable harness. The fuel gauge showed the correct amount of “fuel” as well. Last test was the “evil eye”, the red light that indicates that you have very little fuel left. It turned on as it should, after a couple of minutes. But then it went out after 4-7 minutes. That’s not correct. The “evil eye” should shine until you shut the car off or fill the tank (over the 5-6l threshold). I tried to make a new test but that didn’t work until I had waited at least 20 minutes. Did the bi-metal contact that controls the “evil eye” overheat in any way?

So, I took the gauge out of the cluster and tested it again. The light turned on as it should and didn’t go out even after another test or two. Hmmm… Where could the problem lie? Did it overheat due to bad air circulation when mounted in the cluster? Sounded odd, how would it then be when it was put into the car?! Bad solder joints or even a bad cable harness (which still had the original cables from -57)?

  • Testing the Ponton fuel gauge for full tank
  • Testing the Ponton fuel gauge for half tank
  • Testing the Ponton fuel gauge for almost empty tank
  • Testing that the Pontons fuel reserve lamp works

I went for the two latter possible causes and managed to find new wires with the correct, original color coding in Germany. Delivery took 4w as usual when Deutsche Bundespost and PostNord in Sweden are involved. You cannot stress in the restoration business.

I desoldered the wires from the connections in the base plate of the cluster and dragged them out. Having taken the protective tube off the wires I noticed that the ground wire was stripped from 5cm after the contact. Why it had been stripped I was never able to figure out. I thought that this may had been the cause, some sort of short circuit, but unfortunately, as you will see below, that was not the case.

  • The length of a Ponton instrument cluster cable harness
  • The individual wires in the cable harenss. Note the stripped ground cable
  • New, correctly color coded wires and protective tubes for Ponton instrument cable harness

Drawing of Mercedes Ponton instrument cluster cable harness

Drawing of the instrument cluster cable harness

I started the soldering with the joints on the baseplate of the instrument cluster since I have had problems getting nice solder joints when the wires were cut to length. If I would do this work again, I would however start at the socket end.

  • The wires in the base plate soldered
  • The soldered wires with their protective tubes

Layout drawing of Mercedes Ponton instrument cluster

Layout drawing of the instrument cluster

While making the new harness I also found out that the original solder joints on the socket were not only formed like cubes, but also looked frosted/crystalline. Were they so called “disturbed joints” or had they used another solder? I never found out. I used a large soldering iron directly on the wires to be able to get them out quickly without melting the “solder cubes”. The solder that got stuck on the wires did also lock funny/strange…

In two last pictures below, you can see that the solder joints in the female contact on the main cable harness are not formed like cubes, but cylinders!

  • Socket for Ponton instrument cluster cable harness draged out, first side
  • Socket for Ponton instrument cluster cable harness draged out, second side
  • Rear view of Mercedes 219 instrument cable harness socket and solder joints, first side
  • Rear view of Mercedes 219 instrument cable harness socket and solder joints, second side
  • Old solder joints on wires for instrument cluster
  • Socket on Mercedes Ponton main cable harness, first side
  • Socket on Mercedes Ponton main cable harness, second side

To get the new wires soldered deeply enough into the cubes on the socket I drilled a hole in each cube. The wires were then soldered one by one, being hold steady by a “third hand” whose jaws were covered with tape to protect the cable insulation.

As you may understand it was a bit tricky to solder these wires with such a short length sticking out below the protective tube. So, start your soldering here…

Even though I checked everything 10 times I of course managed to mix two wires up. I noticed it just before I was going to tell my wife that the cluster was finally done. The wire order in the pictures below are however the correct one.

  • Holes drilled in old solder joints
  • Soldering new wires in Mercedes-Benz 219 instrument cluster socket with the help of a third hand
  • Rear view of Mercedes 219 instrument cable harness socket with new wires and solder joints, first side
  • Rear view of Mercedes 219 instrument cable harness socket with new wires and solder joints, first side

Layout of Mercedes Ponton instrument cluster socket wiring

Layout of the instrument cluster socket wiring

With the new cable harness in place I happily hooked everything up for new tests. Sadly, it didn’t work now either. After further research I was sure the bimetal overheated in some way and turned the “evil eye” out prematurely. Looking closer at the contact I realized that the paper wrapping on of the coils seemed to have slid down. You can see this in the fourth picture. In the fifth picture you can see the paper that protects the coil and how close it is to the other part of the contact.

Firstly, one paper wrapping had slid down. Secondly, the wrapping had started to loosen up, the old glue probably didn’t hold any longer. I suspect that when the coil got hot it, together with the wrapping, expanded. And since the distance between the paper and the other part of the contact is so small it disengaged the contact and the “evil eye” turned out prematurely.

Even more problems before the solution

First, I tightened the wrapping of the contact part that is closest to the gauge’s base plate. With a pincette and glue that was not difficult. Then I tried to push the other coil with wrapping upwards and then tighten its wrapping. I almost managed to do that, but unfortunately, I broke the tiny coil wire on the same time. After that the “evil eye” didn’t turn out after a couple of minutes so from that perspective the gauge worked. But it turned on after only 20 seconds of “empty tank”.

I never found a source for this tine wire. It’s said to have very specific specifications in terms of resistance and only ~5/100 mm thick. E.g. has the fuel sending unit of a /8 (W114/115) a wire that has a specific resistance of 292 Ohm/m. If the Ponton fuel gauge has the same wire I was never able to figure out. I got a source for the wire, VDO, but they turned my request down. Let me know if you know the specifications and/or know where to get it.

When you look at the pictures below, remember that the gauge and the cluster are not “laying”, they are “standing up” ;-).

  • Bottom view of Ponton fuel gauge
  • Top view of Ponton fuel gauge
  • Angle top view of Ponton fuel gauge
  • Protective paper on MB 219 fuel gauge bi-metal contact which has slid down and risks breaking the contact when warm
  • Protective paper on MB 219 fuel gauge bi-metal contact which has slid down and risks breaking the contact when warm

Below you can see the wiring diagram of the “evil eye”, the fuel reserve lamp. I have not opened up the fuel gauge and studied the components and wiring of the needle so that is not depicted here.

Electrical scheme of Mercedes Ponton fuel gauge and its fuel reserve lamp with the bi-metal contact

Electrical scheme of the fuel gauge and its fuel reserve lamp with the bi-metal contact

Maybe I’ll continue the search for the wire and repair my old gauge just for the fun of it. But to get some progress with the restoration I decided to search for a new gauge. Karasch could quickly provide me with a NOS fuel gauge.

  • New old stock Mercedes Ponton fuel gauge in box
  • New old stock Mercedes Ponton fuel gauge in box
  • Front view of Ponton fuel gauge
  • Right side view of MB 219 fuel gauge
  • Top view of new Mercedes fuel gauge
  • Left side view of MB 219 fuel gauge
  • View of bottom om new W105 fuel gauge
  • Bi-metal contact on Ponton fuel gauge
  • Bi-metal contact on Mercedes-Benz 219 fuel gauge

Final assembly

With the new gauge in place everything worked as it should. Now it was time to finalize the front plate. Based on the old vinyl I cut new pieces of 1079 “Roser red” vinyl and glued them onto the front plate. Most of the vinyl on top of the front plate will be covered by the wood that lays on top of the dash, just behind the wind screen. The frame was re-chromed, and I got new 2mm foam rubber from Ka-Ja Tachodienst to place between the frame and the glass pieces. The assembly was easy. Insert the tabs of the frame into their holes in the front plate. Carefully, but firmly, press the frame into a tight position and then turn the tabs 90 degrees. Done.

  • Old, lower part of vinyl for Ponton instrument cluster
  • Old, upper part of vinyl for Ponton instrument cluster
  • Foam rubber for holding glas in Mercedes instrument cluster
  • All parts for the Mercedes instrument cluster, ready for assembly
  • Glass in place on Mercedes instrument cluster front plate
  • Restored Ponton instrument cluster front plate assembled

Then you assemble the base plate with all its instruments with the front plate, taking care of getting the “big” foam rubber in place. Carefully, but firmly, press the base plate and front plate together and tighten the screws on the backside.

The cluster is beautiful and knowing that everything is 100% OK makes it even more beautiful. Now it’s just a matter of making some progress with the rest of the restoration so that I can put it where it belongs, in the dash.

Restored Mercedes-Benz 219 Ponton instrument cluster

The completely restored instrument cluster

The clock

This is a mechanical clock. A lot of people have recommended me to replace it with the later, electrical version. For me that’s a big No. Winding the clock is for me something special; you close the door, settle in and wind the clock as a preparation for the trip. And there is nothing more relaxing than coming home with the car, parking it in the garage and listen to the clock’s tick-tack for a couple of minutes. Winds me down…

The cover glass of the clock was broken and the small rubber sealing that sits on the shaft where it goes through the glass was old and dry. New was ordered from Ka-Ja TachodienstKa-Ja Tachodienst together with the new rubber sealing for the shaft. The chrome frame was taken off. On the rear-side there was rubber melted (?) into it, I assume for vibration dampening. After pealing it off the frame was sent for re-chroming since my father have had it off for servicing of the clock and therefore it was slightly bent and damaged.

  • Ponton wind-up clock with broken glass
  • New glass and rubber sealing
  • Chrome frame taken off
  • Rubber between clock housing and frame

I also wanted to have the clock mechanism gone through. Hence, I had a watchmaker go through it. There was nothing to repair or replace except dirt and old, hardened oil and grease. That was removed and the mechanism re-oiled.

  • The clock was gone through, old hardened oil, grease and dirt removed and new oil put in place, first picture
  • The clock was gone through, old hardened oil, grease and dirt removed and new oil put in place, second picture
  • The clock was gone through, old hardened oil, grease and dirt removed and new oil put in place, third picture
  • The clock was gone through, old hardened oil, grease and dirt removed and new oil put in place, fourth picture

With everything gone through and frame re-chromed the assembly was easy and the result perfect.

  • All parts for Ponton W105 manual clock ready for assembly
  • Restored Ponton W105 manual clock assembled