For those considering a vintage diesel, the 1977 Mercedes Benz 300d often comes up in discussions. Enthusiasts appreciate this model, and for good reason. If you’re prepared for some hands-on involvement, owning a 1977 300D can be a rewarding experience. With access to a good repair manual, like Haynes or the official M-B manual, and resources from online communities, tackling repairs on a 1977 300D is quite manageable for the DIY mechanic. Parts availability is also decent, with suppliers like Fast Lane offering reasonable prices and salvage yards specializing in Mercedes-Benz parts to further reduce costs. A pre-purchase inspection (PPI) by a qualified mechanic is always a smart move to understand the car’s current condition before you buy.
One characteristic of the early 300D models is their slower acceleration from a standstill. This is partly due to the automatic transmission starting in 2nd gear. However, there are simple ways to start in 1st gear. You can manually select “L” on the gear selector, or fully depress the accelerator pedal to engage the kick-down switch, forcing a shift to 1st. Many drivers find manually selecting 1st gear, especially when running the air conditioning, provides a more responsive start.
Another point to consider for the 1977 300D is the injection pump. Early models had a known issue with a copper sealing washer. Mercedes-Benz addressed this with several modifications to the washer design. A failing washer can lead to diesel leakage, reducing power as the injection pump struggles to maintain pressure. Replacing these copper sealing washers is a straightforward task, although it can be messy as diesel fuel will drain from the pump. After replacement, priming the injection pump is necessary before restarting the engine.
Despite these points, the 1977 300D is renowned for its robust construction and longevity. Regular maintenance is key to keeping these cars running reliably for many years. This includes consistent oil and filter changes every 3,000 miles using a quality diesel-rated 15W-40 oil, regular air filter changes, valve adjustments every 10,000-15,000 miles, maintaining correct coolant levels, annual brake fluid changes, and keeping an eye on belts and hoses.
Consumer Reports recognized the early 300D models as a “best buy” used car for multiple years. This rating was based on factors like reliability, minimal repair costs, safety, and overall quality. If you are looking for a dependable classic diesel that you can maintain yourself, the 1977 Mercedes Benz 300D is definitely worth considering.
