No electric fuel pump, just a mechanical lift pump by the IP. If it's old or has a lot of miles, replace with a new BOSCH pump.
Temp gauge sender unit is located on the cylinder head, which will require intake manifold removal to get to. HOWEVER, your symptoms appear to be likely caused by the dreaded eco junk wiring MBs from this era were plagued with. Look for the 2 wire connector by the upper radiator outlet on the engine side. If the insulation is cracked or missing you'll need a whole new engine wiring harness. Without a solid harness, these cars are almost impossible to troubleshoot. At least you have a diesel, which simplifies things a bit but there is no avoiding the eco junk if it has not been adressed yet.
See this link. Same car different engine, but similar symptoms.
PeachPartsWiki: W124 Engine Wiring Harness Replacement
Fuel leaks are not unknown on these cars. Simply replace all the fuel lines with new MB parts, and update the IP fuel lines around the IP as needed with the banjo bolt type connection. Not very expensive and will last a very long time.
The dealer can get you the radio code key IF your car still has the factory installed unit with the appropriate s/n#. There is no one master code that unlocks all radios.
For the tachometer, start by replacing the OVP relay with a new genuine MB or KAE(hler) relay. Also replace ALL the fuses in the fusebox with the updated copper core fuses. Again, this is needed to establish a solid electrical baseline.
The vinyl does delaminate, especially around the door pockets. Can be reglued using 3M automotive adhesive and some plastic clamps bought from Home Depot or Lowe's.
Temp gauge sender unit is located on the cylinder head, which will require intake manifold removal to get to. HOWEVER, your symptoms appear to be likely caused by the dreaded eco junk wiring MBs from this era were plagued with. Look for the 2 wire connector by the upper radiator outlet on the engine side. If the insulation is cracked or missing you'll need a whole new engine wiring harness. Without a solid harness, these cars are almost impossible to troubleshoot. At least you have a diesel, which simplifies things a bit but there is no avoiding the eco junk if it has not been adressed yet.
See this link. Same car different engine, but similar symptoms.
PeachPartsWiki: W124 Engine Wiring Harness Replacement
Fuel leaks are not unknown on these cars. Simply replace all the fuel lines with new MB parts, and update the IP fuel lines around the IP as needed with the banjo bolt type connection. Not very expensive and will last a very long time.
The dealer can get you the radio code key IF your car still has the factory installed unit with the appropriate s/n#. There is no one master code that unlocks all radios.
For the tachometer, start by replacing the OVP relay with a new genuine MB or KAE(hler) relay. Also replace ALL the fuses in the fusebox with the updated copper core fuses. Again, this is needed to establish a solid electrical baseline.
The vinyl does delaminate, especially around the door pockets. Can be reglued using 3M automotive adhesive and some plastic clamps bought from Home Depot or Lowe's.
