Answer
Aug 10, 2025 - 04:07 PM
If your W123’s been sitting for 5 years, there’s a good chance the fuel system has varnish, rust flakes, or sludge in it. So be ready for a bit of a mess ✌🏻
On most W123s (diesel or petrol), the fuel line runs along the underside of the car from the tank to the engine bay. To remove and clean it:
- Work safe – Disconnect the battery, work in a well-ventilated area, and keep a fire extinguisher handy.
- Drain the tank – Pull the drain plug on the bottom of the fuel tank (if fitted) or use a siphon pump. Old fuel will smell awful.
- Disconnect at both ends – Undo the fittings at the tank outlet and up front at the fuel pump/filter. Have rags and a container ready for any fuel left in the line.
- Free the line – It’s usually clipped to the body with small metal/plastic clips. Gently pry it out without bending it if you plan to reuse it.
- Cleaning – You can flush it with fresh fuel, carb cleaner, or compressed air. If it’s badly corroded inside, replacement is safer than cleaning.
- Inspect the rubber hoses – Any flexible fuel hose sections will almost certainly be brittle and cracked after 5 years — replace them while you’re in there.
Of course, that's just a general procedure. The service manual will usually cover this procedure in detail for your exact model. So feel free to reach out to us with your W123's model and year so we can assist you further.
