1990 Mercedes 420 4.2L Petrol · G5 JRP

A thirty-six-year-old Mercedes-Benz 420 with this MOT profile tells a consistent story of corrosion-related advisories centred on the braking and suspension systems, alongside persistent front brake caliper binding. Across the eight recorded tests since 2018, every annual examination has returned at least one advisory, and the most recent pass on 18 September 2025 carries four. Two of those latest advisories flag both rear brake pipes as corroded though coated in grease or similar material, continuing a brake pipe corrosion theme that first appeared on the nearside front in 2018 and has since broadened to the rear axle. The repeated advisories for nearside and offside front coil spring corrosion from 2023 and 2024, alongside the 2025 brake binding entries, suggest deterioration that is progressing rather than resolving. There are no recorded failures, which keeps the vehicle on the road legally, but the accumulating advisories point to a chassis and braking system approaching the point where items may cross from advisory to defect territory. The recorded mileage of 67,069 miles against a 1990 registration equates to roughly 1,863 miles per year averaged across the vehicle's life, which is notably low for a car of this age. Annual mileage at that level is typical of a second or weekend vehicle rather than a daily driver, and the DVSA record shows tests in consecutive years from 2018 through 2025 with no gaps, indicating the car has been in regular use and presented for testing throughout that period. Lower annual mileage of this kind generally reduces wear on major drivetrain components but can accelerate corrosion on unprotected ferrous parts such as brake lines, suspension springs, and subframe elements, since short journeys do not always generate enough heat to fully dry the underbody after wet weather exposure. The pattern of brake pipe, coil spring, and bumper corrosion advisories fits that profile. The 2019 and 2021 advisories for thin rear brake pads and a worn rear pad set respectively also indicate that braking consumables are wearing progressively despite the modest mileage. For a prospective buyer, the priority areas on inspection are the brake hydraulic circuit and front suspension. The brake pipe advisories from 2018, 2024, and 2025 suggest that the copper or steel lines may be developing surface corrosion under the protective coating, so a thorough underbody check should be carried out with the vehicle on a ramp, looking for pitting, flaking, or weeping joints along the full length of the front-to-rear brake lines, particularly at unions and clips. Because both front calipers have been flagged as binding on three consecutive tests, the caliper sliders, guide pins, and piston seals should be inspected for stiffness, and on a test drive any tendency for the car to pull to one side under light braking, a hot wheel hub after a journey, or uneven pad wear across the front axle would warrant closer investigation. The 2023 and 2024 advisories for corroded front coil springs mean the spring seats and lower spring pans should be examined for cracking or loss of material, as corroded springs on a W126-platform Mercedes can eventually snap and damage the tyre sidewall. Additional checks should focus on the remaining advisories from the record. The 2020 minor defect for a deteriorated offside front ball joint dust cover is worth verifying, since a perished boot allows water and grit into the joint and accelerates wear; listen for clonks over speed humps and check for vertical play at the front wheels with the car lifted. The general underbody and subframe condition should be inspected given the recurring corrosion theme, paying particular attention to jacking points, sill seams, and the rear axle mounting areas, which on these cars are known to suffer from hidden rust. On the test drive, the V8 should be allowed to reach full operating temperature, after which any hesitation, uneven idle, or excessive exhaust smoke should be noted, and the transmission should be checked for smooth shifts through all gears. Finally, confirm that the previously disconnected headlight washers have been rectified and inspect the bumper mounting brackets, as corrosion there can spread to the front panel and headlamp mounting points.