Len Sokoloff / firstname.lastname@example.org / 1959 Type 220S cabriolet
I performed this job on my 220S cabriolet. The Ponton sedans are a little different. The sedans have a panel on the firewall that can be removed to yield better access to the rear of the instrument cluster. I have never actually done one or seen one, but I understand that removing and replacing the cluster in a sedan is very easy compared to the cabriolet.
It has been awhile since I removed the instrument cluster in my Ponton but I have removed it several times for various reasons and have not enjoyed it. But it does get easier each time you do it. Here is what I remember.
Lay a rag or a towel on the dash wood and steering wheel so you do not scratch anything when you take the cluster out. It might even be a good idea to put a strip of masking tape along the dash wood just under the cluster.
Unscrew the capillary tube for the water temp gauge on the cluster. It is on the driver's side of the engine block. Have something ready to plug the hole. I use a cork. The whole tube comes out through the firewall when you remove the cluster, so see what other attachment points there are. I think there is a clamp on the battery tray shelf too.
There are two large springs that hold the cluster in place. They can be seen from underneath. Disconnect them at either end but I find installation is much easier if the spring is attached to the cluster when it goes back in.
Remove the knob from the trip meter button by pulling the knob out so that you can grasp the shaft while you unscrew the knob. Then pull the trip meter cable out with the cluster.
Unscrew the electrical connection. There are two screws holding the two parts together. You might be able to do this or might have to do this when the cluster is pulled away from the dash a little bit. I remember marking mine with a dab of paint before I disconnected it so I knew which way it went back together. It may only go back together one way though, but I was not sure the first time. It is a pretty big eight pin connector with a pretty big wire bundle so you will not miss it very easily.
Pull the cluster out far enough to be able to get to the speedometer cable which can also be done from underneath but is easier sitting in the driver's seat.
Disconnect the oil pressure gauge line - maybe a 17 mm wrench?
Pull out the cluster along with the capillary tube.
Of course, installation is the reverse of removal. Upon installation here is what I have found. Be careful with the metal oil pressure line. Watch so that you do not kink it. Do not start your car with this oil pressure line off. I have heard that oil will shoot all over the damn place in your engine compartment. It is a good time to change all of your light bulbs in the cluster, even if they are working. Also a good time to paint your needles if they are dull. Make sure all the light bulb contacts are bent down on the bulbs so they make contact and will light. Good time to clean up the contacts in the electrical connection. I have found that using a piece of solid steel (or wood) dowel as a home-made spring puller helps to get the springs back on. I contort myself under the dash so that I can see where the springs are to go, then try to push the spring up onto the pin that holds it using the dowel. If you find an easier way, I want to hear about it. You have to reach under the dash and pull the oil pressure line back enough so the cluster can seat itself. You might have to do this a couple of times as you coax the cluster into position.
That is all I can think of right now. If I left out anything, someone please let us know. It really is not a hard job. I just find it tedious getting the cluster back in and fighting those springs.
Addendum #1 / October 16, 2016
IPOG forum message from Chuck Taylor
Here are a few final suggestions about servicing the instrument cluster.
1. There is usually plenty of slack in the capillary line to the temperature gauge. Once the speedometer cable and oil pressure line have been disconnected, a small screwdriver can be used to remove the gauge from the cluster. This saves having to drain off coolant and you don't have to remove the sender and risk twisting the line.
2. On the coupé or cabriolet, it may be easier to access the retaining springs by removing the radio or trim plate and reaching in through the opening.
3. If you replace the speedometer cable on the coupé or cabriolet, unfastening the brake booster and pulling it forward provides access to the firewall grommet, which needs to be removed and installed on the new cable (or a new one installed).
1959 Mercedes-Benz Type 220S sedan
Falls Church, Virginia
Created: November 19, 2003 / Jeff Miller
Last Update: October 17, 2016