🚗 Classic Fault — Mercedes-Benz (1976–1985)
W123 rust in sills and floor
💰 Estimated Repair Cost
$200 – $1500 GBP
Parts and labour estimate
🔧 Tools Required
Welder, angle grinder, rust treatment
📋 Overview
Despite reputation for durability, W123 sills and floor areas rust from inside out when drainage holes block.
🩺 Symptoms
- Visible rust bubbling under paint on lower sills
- soft spots in floor when pressed
- water in boot or footwells
🔍 Possible Causes
- Blocked sill drainage holes trapping water
- paint chip allowing moisture ingress
- poor underseal
🛠️ Diagnosis Steps
Probe sills with screwdriver — solid or hollow sound. Check drain holes in sill ends are clear. Inspect under carpets
✅ Most Confirmed Fix
Sill and floor repair welding
70% of users confirm this fix worked (31 reports)
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