Mercedes-AMG C63 W205 Common Problems: The 5 Failures Every Owner Faces

Published on: Sun Jan 18 2026

The Reality: 5 Problems Every W205 C63 Owner Will Face

If you own or are considering a Mercedes-AMG C63 W205 (2015-2021), you need to understand the real-world failure patterns that define M177 ownership.

This is not a “lemon” problem. These are structural weak points that appear across the entire W205 C63 platform, regardless of maintenance quality.

1. Oil Separator Failure → Engine-Out Repair ($8,000-$12,000)

The Failure Pattern

Mileage: ~55,000 miles
Affected Years: 2018-2019 (documented), but spans into at least 2019 across M177 platform

What Happens

The crankcase ventilation system (oil separator) fails and over-pressurizes the crankcase, blowing out:

• Rear main seal
• Front crank seal
• Valve cover gaskets

Symptoms You’ll Notice

• Heavy oil smell
• Oil puddles under the car
• Oil on undertray/subframe
• Engine must be removed for diagnosis

The Cost Reality

This is not a “top off the oil” problem. This is an engine-out repair at 55,000 miles on a premium AMG.

Owner Sentiment

“Oil separator failure over-pressurizes the crankcase and blows out seals. Unacceptable for a premium AMG at this mileage.”
— Independent Mercedes specialist (603 MTech Autowerks)

2. Chronic Oil Leaks (60,000-100,000 Miles)

The Failure Pattern

Mileage: 60,000-100,000 miles
Affected Years: 2015-2018 W205 C63/C63 S

Common Leak Sources

1. Valve Cover Gaskets

   • Cost: $800-$1,500 (independent)
   • Labor-heavy due to tight V8 bay

2. Oil Pan Gasket

   • Cost: $900-$1,800 (independent)
   • Requires subframe drop

3. Oil Cooler Seals

   • Cost: $300-$700 (independent)
   • Front-end damage risk (stone impact)

Symptoms

• Burning oil smell
• Visible oil on undertray
• Drips at rest
• No immediate drivability issue

The Compounding Problem

Many owners face multiple leak sources simultaneously around 70,000-100,000 miles, turning a $1,000 repair into a $3,000+ reseal job.

Owner Sentiment

“Oil everywhere on the belly pan. Typical M177 leaks starting around 100k km. Annoying but resigned—viewed as ‘Mercedes tax’ but still unacceptable this early for a premium car.”
— Reddit r/AMG long-term owner

3. MCT Transmission Overheating (Track Use)

The Failure Pattern

Mileage: 20,000-60,000 miles (track-used cars)
Affected Years: 2015-2017 W205 C63/C63 S

What Happens

The AMG SPEEDSHIFT MCT 7-speed transmission overheats on track, triggering:

• Limp mode
• Loss of power
• Slow, unresponsive shifts

The Cost Reality

Owner Sentiment

“Transmission kills it for me. MCT overheated and went into limp mode at the track. Not fit for serious track use.”
— Bimmerpost cross-shop thread (M3/M4 vs C63)

Many enthusiasts choose M3/M4 instead due to this single issue.

4. Water Pump / Vacuum System Failure

The Failure Pattern

Mileage: 30,000-70,000 miles
Affected Years: 2015-2020 W205 C63/S

What Happens

Water pump fails, allowing coolant to contaminate vacuum lines and shut-off valves.

Symptoms

• Coolant loss (no obvious puddle)
• Check-engine light
• Underboost / drivetrain warnings
• Vacuum-system faults

The Cost Reality

Owner Sentiment

“Another water pump statistic. Coolant ended up in vacuum lines. Too early for a pump on a $80k+ car.”
— Reddit r/Audi (same EA839/M177 pump design)

5. Misfire / Hesitation Under Load

The Failure Pattern

Mileage: ~60,000 km (37,000 miles)
Affected Years: 2016-2019 W205 C63

Symptoms

• Jerking during acceleration when warm
• Power drop and difficulty revving
• Occasional misfire feeling
• Engine feels “restricted”

Common Fixes

Owner Sentiment

“Early M177s prone to running issues… coils, exhaust clamps, cracked intake manifolds, failing low-pressure pump & worst being engine failure. A nightmare to fix when misfire clusters appear.”
— Reddit r/AMG experienced member

Mileage-Based Failure Timeline

0-50,000 Miles

• Water pump failure (30k-50k range)
• Misfire clusters (37k+ range)
• Oil separator risk begins (50k+)

50,000-80,000 Miles

• Oil separator catastrophic failure (~55k miles, engine-out)
• Valve cover leaks begin (50k-80k)
• MCT overheating (track cars)

80,000-100,000+ Miles

• Chronic oil leaks (valve covers, pan, cooler)
• Turbo oil leaks (hot-V lines)
• Differential noise (higher-mileage cars)

The Ownership Reality

Total Cost of Common Failures (First 100,000 Miles)

Conservative Estimate:

• Oil separator (engine-out): $10,000
• Valve cover gaskets: $1,200
• Water pump: $1,400
• Coils/plugs: $600
• Total: ~$13,200

Realistic Estimate (Multiple Leaks):

• Oil separator: $10,000
• Valve covers + oil pan + cooler: $3,000
• Water pump: $1,400
• MCT service: $700
• Coils/plugs/fuel pump: $1,500
• Total: ~$16,600

Should You Still Buy a W205 C63?

✅ Buy If:

• You have a $15,000-$20,000 maintenance reserve
• You plan to use an independent Mercedes specialist
• You avoid track use (MCT overheating)
• You accept that oil leaks are inevitable

❌ Avoid If:

• You expect “set and forget” reliability
• You cannot afford engine-out repairs
• You plan heavy track use
• You want a car you can sell easily after 60k miles

Related Guides

Understand the full reliability picture:

• Mercedes-AMG C63 W205 Reliability Deep Dive
• Mercedes-AMG C63 W205 Ownership Costs
• Mercedes-AMG C63 W205 Buying Guide

Compare with rivals:

• BMW M3 F80 Reliability
• Audi RS5 B9 Reliability