Mercedes 450 Troubleshooting

1. Pop the hood on the 450 and look at the spark plug wiring. The V-8 requires strong currents to spark the combustion chambers, and any corrosion in the wires can deprive the spark plugs of current. The intake manifold should be free of rust, as well as the carburetor on top. Look around the edge of the engine where the intake manifold meets the lower block for signs of oil leaks. The gasket could have gone bad or there could be micro fractures. If the engine is broken then consider an engine swap to something newer like a Chevy short block. Old Mercedes engines can be very expensive to repair.
2. Start the 450 up and listen for the engine to make any noises. The 4.5L Mercedes V-8s make a soothing rumble when running normally. Any banging or scrapping could indicate a broken camshaft or pistons. Shut the Mercedes Benz off immediately and call a mechanic if that happens. You will either have to rebuild the engine or swap it out.
3. Shift into drive and take the Mercedes Benz 450 for a test drive. If the throttle tip in feels too sudden then the carburetor may be malfunctioning, making the fuel air mix too rich. Look at the engine temperature as you cruise on the highway. If the engine temperature gets into the red band, then the radiator is damaged or the coolant lines are pinched somewhere. For longevity, it is best to equip older V-8s with auxiliary fans to keep them cool. The Mercedes Benz V-8 of the '70s was all steel, so it retained heat more than newer V-8s that have fast-cooling aluminum parts.