Mercedes-Benz G-Class (1975–2001) – Fuel Tank Cleaning & Maintenance Guide
Why You Should Check or Clean Your Fuel Tank on High-Mileage or Long-Stored G-Class Models
The classic Mercedes-Benz G-Class (W460, W461, W463) from 1975 to 2001 is famed for durability. Still, with high mileage or long periods of storage one frequently overlooked item is the fuel tank. Contaminated or degraded tanks cause fuel delivery problems, poor engine performance and can damage injectors and pumps.
Common Problems with Old G-Class Fuel Tanks
Rust and Corrosion Inside the Tank
Early G-Class models often used steel tanks. When a vehicle is stored with a low fuel level, condensation forms and the internal surface can rust. Rust flakes may enter the fuel stream and clog filters or wear out the fuel pump.
Sediment and Fuel Deposits
Over decades, impurities accumulate at the tank bottom:
- Rust particles
- Dirt and dust
- Degraded fuel residues
- Organic buildup (especially in older diesel models)
These sediments can block the in-tank mesh filter or the main inline fuel filter, reducing fuel flow and causing running issues.
Condensation and Microbial Issues (Diesel)
Long storage in humid climates encourages water condensation. In diesel tanks, this can allow microbial growth (so-called diesel algae), producing sludge and clogged filters.
Why Low Fuel Level During Storage Is Dangerous
When the tank is nearly empty, the exposed interior surface oxidizes faster. Fuel residues thicken and can adhere to the bottom. On the next start the pump can draw in contaminated fuel and distribute it throughout the system.
Recommended Maintenance and Cleaning Procedures
Minimum Recommended Steps
- Completely drain old fuel and inspect the drained fuel for dirt or rust particles.
- Rinse the tank with clean fuel or a dedicated fuel system cleaner.
- Inspect and clean or replace the in-tank mesh filter on the sender unit.
- Replace the external fuel filter as a preventive measure.
Complete (Optimal) Procedure
- Remove the tank from the vehicle for full inspection.
- Check the interior for rust, scale and deposits.
- If rust exists — perform mechanical cleaning (brushing/media) or chemical derusting.
- Rinse thoroughly and allow to dry.
- Apply an internal anti-corrosion treatment suitable for fuel tanks (if recommended for steel tanks).
- Replace seals, gaskets, vent hoses and hose clamps during reassembly.
Notes on Plastic Tanks
Later W463 and replacement tanks can be plastic — they resist corrosion but still collect sediment and should be checked and flushed if contamination is suspected.
Benefits of a Clean Fuel Tank
Improved Fuel System Reliability
Clean tanks reduce the chance of clogged filters and premature pump failure.
Better Engine Performance
Stable fuel supply improves starting, idle and overall drivability.
Longer Component Life
Injectors and pumps last longer when not exposed to contaminated or abrasive particles.
Additional Tips for Long-Term Storage (Europe)
Storage checklist
- Keep tank ≥ 90% full to minimise condensation.
- For diesel vehicles use tested biocide/stabiliser products if microbial growth is suspected.
- Start the engine occasionally and run for a short time to circulate fuel.
- Inspect fuel lines, vent hoses and tank straps for corrosion or cracking.
Conclusion
Mercedes-Benz G-Class (1975–2001) are robust vehicles, but preventive maintenance of the fuel tank is critical after high mileage or long storage with low fuel. At minimum — drain, inspect, flush and check the internal mesh filter. For heavy corrosion or persistent contamination consider tank removal, mechanical cleaning and anti-corrosion treatment.
Regular attention to the fuel tank will reduce unexpected faults and extend the life of the fuel system components.
And if it’s time to replace your old fuel tank, you can order a brand-new plastic fuel tank for your Mercedes-Benz G-Class today from Plasticautotank.com — built to last, fully corrosion-resistant, and 100% compatible with original mounting points and fuel systems. Choose reliability and long life for your G-Wagen!