The Mercedes-Benz M157 is a hand-built, 5.5-liter twin-turbocharged V8 that represents the pinnacle of AMG's engineering ambition in the early 2010s. Developed as the forced-induction successor to the naturally aspirated Mercedes-Benz M156, the M157 traded the M156's high-revving character for brutal low-end torque and significantly improved efficiency — all while delivering more power. Produced between 2010 and 2020, it served as the heart of AMG's flagship performance models, from the ferocious E 63 AMG to the imposing G 63 AMG.
What makes the M157 special in the enthusiast community is its combination of raw output — up to 577 hp in top-spec form — and real-world usability. Unlike its predecessor, this engine was designed from the start to live comfortably in both track and daily-driver scenarios. Its AMG SPEEDSHIFT MCT pairing and all-wheel-drive availability made it exceptionally accessible. For buyers, collectors, and tuners researching used AMG vehicles, this guide covers everything you need to know.
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Base Specifications
| Attribute | Details |
|---|---|
| Type | Twin-turbocharged V8, 90° bank angle |
| Displacement | 5,461 cc (5.5 L) |
| Block | Aluminum alloy |
| Head | Aluminum alloy, DOHC |
| Valvetrain | 32-valve, 4 valves per cylinder |
| Injection | Direct injection (Stratified Charge Combustion) |
| Production Years | 2010 – 2020 |
M157 — 518 hp / 516 lb-ft
The base variant of the M157 delivered 518 hp and 516 lb-ft of torque, powering the standard AMG models that launched the engine's production run. This tune offered a strong balance of performance and engine longevity.
| Model | Chassis | Years |
|---|---|---|
| CL 63 AMG | C216 | 2011–2014 |
| S 63 AMG | W221 | 2010–2013 |
| E 63 AMG | W212 | 2011–2013 |
| CLS 63 AMG | W218 | 2011–2014 |
| SL 63 AMG | R231 | 2012–2016 |
M157 (S-model) — 557 hp / 590 lb-ft
The S-model (high-performance) variant introduced a higher boost tune and increased torque output. It typically came paired with AMG's 4MATIC all-wheel-drive system in select applications.
| Model | Chassis | Years |
|---|---|---|
| E 63 AMG S | W212 | 2013–2016 |
| E 63 AMG S | S212 | 2013–2016 |
| CLS 63 AMG S | W218 | 2013–2016 |
| S 63 AMG | W222 | 2013–2017 |
| CL 63 AMG | C217 | 2014–2017 |
| SL 63 AMG | R231 | 2016–2020 |
| G 63 AMG | W463 | 2012–2018 |
| ML 63 AMG | W166 | 2012–2015 |
| GL 63 AMG | X166 | 2013–2015 |
| GLE 63 AMG S | W166 | 2015–2018 |
| GLS 63 AMG | X166 | 2016–2019 |
How to check a used M157-powered car's history
Before buying any used car equipped with the M157, it is essential to ensure full transparency about its past. Undisclosed accidents and hidden mechanical abuse can directly compromise safety and reliability — and with a hand-built AMG engine, the stakes are even higher.
The M157 is a magnet for enthusiastic driving and aftermarket tuning. A prior owner may have run aggressive ECU tunes, pushed the engine hard on track without proper maintenance, or deferred critical services like rod bearing inspections, spark plug replacements, or turbocharger oil line servicing. Mileage rollbacks are also a concern on high-value AMG vehicles. Given these risks, it is strongly recommended to check the vehicle's complete history using its license plate or VIN number before any purchase decision.
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Key Strengths
The M157 earns its reputation through a combination of engineering excellence and brute-force performance that few engines in its era could match. The twin-turbocharged architecture delivers massive torque from very low rpm — something the naturally aspirated M156 could never replicate — making the M157 genuinely effortless in daily driving while remaining terrifyingly fast on demand.
Each unit is hand-assembled by a single AMG technician, a tradition reflected in the engine's quality and attention to detail. The aluminum block and heads keep weight in check, while the direct injection system improves thermal efficiency and fuel economy compared to older AMG V8 designs. Long-term durability, when properly maintained, is genuinely impressive for a forced-induction engine at this output level.
The aftermarket support for the M157 is substantial and growing. Reputable tuning houses offer ECU remaps, downpipes, intercooler upgrades, and turbo inlet pipes that can safely push output well beyond 600 hp on the stock hardware. Compared to the Mercedes-Benz M278, the M157's performance-focused DNA gives it a clear edge for enthusiasts seeking meaningful gains.
Known Reliability Issues
Camshaft Adjuster (Phaser) Failure
Symptom: Rough idle, rattling noise on cold start, check engine light with camshaft timing codes.
Cause: The camshaft phasers on the M157 are susceptible to wear, particularly when oil change intervals are extended or when low-viscosity oil is used. Sludge buildup accelerates phaser wear significantly.
Severity: Moderate
Typical Mileage: 60,000 – 100,000 miles
Note: Using the correct MB 229.5 or 229.51 specification oil and adhering to strict 10,000-mile oil change intervals is the primary preventive measure.
Turbocharger Oil Line Deterioration
Symptom: Oil consumption, blue smoke from exhaust, visible oil seepage near the turbocharger housings.
Cause: The oil feed and return lines supplying the twin turbochargers use rubber sections that harden and crack with age and heat cycling. Failure can lead to oil starvation of the turbocharger bearings.
Severity: Critical
Typical Mileage: 70,000 – 120,000 miles
Note: Preventive replacement of both turbo oil lines is strongly recommended on any M157 approaching 80,000 miles. Failure to address this can result in catastrophic turbo failure and internal engine contamination.
Spark Plug and Ignition Coil Wear
Symptom: Misfires, rough running at idle or under load, reduced power output, P0300-series fault codes.
Cause: The M157's high-compression, direct-injection environment accelerates spark plug electrode wear. Coil packs degrade in tandem, particularly on high-mileage units that have not had plugs replaced on schedule.
Severity: Moderate
Typical Mileage: 40,000 – 60,000 miles
Note: Replace all eight spark plugs and inspect ignition coils simultaneously. Using OEM or equivalent NGK plugs is advised.
Cylinder Scoring
Symptom: Persistent oil consumption, blue smoke from the exhaust, rough running, and in severe cases low compression or internal engine noise.
Cause: Cylinder scoring happens when the piston and cylinder wall make abnormal contact, usually due to poor lubrication, overheating, detonation, or long-term wear under heavy load. On high-performance engines, it can also be aggravated by repeated hard use, tuning, or neglected maintenance.
Severity: Critical
Typical Mileage: 80,000+ miles
Note: Mild cases may show up as increased oil use before any major drivability symptoms appear, but severe scoring usually requires major engine repair or replacement.
Coolant System Leaks (Expansion Tank and Hoses)
Symptom: Coolant loss, overheating warning, visible white residue near plastic fittings or the expansion tank.
Cause: The plastic coolant expansion tank and associated hoses deteriorate with age. Pressure cycling weakens connection points, leading to small but progressive leaks that can quickly escalate.
Severity: Moderate
Typical Mileage: 80,000 – 130,000 miles
Note: Replacing the expansion tank, cap, and all aging coolant hoses as a preventive set is cost-effective insurance against a roadside failure.
Oil Consumption
Symptom: Needing to top up oil between service intervals, blue tint in exhaust.
Cause: Some M157 engines consume oil at a higher rate than expected, attributed to piston ring wear and valve stem seal degradation over time, especially on hard-driven examples.
On several cases, oil consumption has been attributed to cylinder scoring, requiring a complete engine block change.
Severity: Minor to Critical
Typical Mileage: 80,000+ miles
Note: Consumption under 1 quart per 1,000 miles is generally considered within tolerance by Mercedes-Benz AMG. Anything above that warrants a compression and leak-down test.
Maintenance Schedule
| Service | Interval |
|---|---|
| Engine oil and filter change | Every 10,000 miles (or annually) |
| Spark plug replacement | Every 40,000 – 50,000 miles |
| Air filter replacement | Every 20,000 miles |
| Fuel filter replacement | Every 30,000 miles |
| Coolant flush | Every 4 years or 60,000 miles |
| Transmission fluid (MCT/7G-Tronic) | Every 40,000 miles |
| Turbo oil lines inspection | Every 60,000 miles (replace if cracked) |
| Intake valve cleaning (walnut blast) | Every 60,000 – 80,000 miles |
| Drive belt and tensioner inspection | Every 60,000 miles |
Recommended oil specification: Mercedes-Benz MB 229.51 (0W-40 or 5W-40 full synthetic). Do not use oils that do not meet this specification — the M157's variable valve timing system and turbocharger bearings are particularly sensitive to oil quality.
Tuning Potential
| Stage | Modifications | Estimated Power |
|---|---|---|
| Stage 1 | ECU remap (software only) | 580 – 620 hp |
| Stage 2 | ECU remap + downpipes + intercooler upgrade | 640 – 680 hp |
| Stage 3 | Stage 2 + upgraded turbo inlets + fueling upgrades | 700 – 750 hp |
| Stage 3+ | Full bolt-on + port/fuel injector upgrades + supporting mods | 780 – 850 hp |
Recommended first modifications (in order of priority):
- ECU remap from a reputable AMG specialist (Renntech, Weistec, Eurocharged) — biggest gain per dollar
- Aftermarket downpipes (catless or high-flow catted) — significant power and throttle response gains
- Intercooler upgrade — critical for sustained power under heat soak conditions
- Turbo inlet pipes — improved airflow with minimal installation complexity
- Oil cooler upgrade — recommended before sustained track use
- High-flow fuel injectors — necessary above approximately 700 hp
At outputs above 750 hp, the stock turbochargers and fuel injectors become the limiting factor. The transmission, particularly the MCT unit, should be upgraded with a performance torque converter and fresh fluid if sustained track use is planned. Fueling must be carefully matched to power increases — the stock direct injection system operates at its limits above 700 hp without supplemental port injection.
FAQ
Is the Mercedes-Benz M157 a reliable engine?
For a hand-built, twin-turbocharged engine producing over 500 hp, the M157 is genuinely reliable when properly maintained. The most critical factor is strict oil change discipline and using the correct oil specification. Neglected examples can develop serious issues, but well-maintained units regularly exceed 150,000 miles without major intervention.
What are the most common problems with the M157?
The most frequently reported issues are camshaft phaser wear, turbocharger oil line deterioration, carbon buildup on intake valves, and spark plug/ignition coil degradation. Of these, the turbo oil lines are the most critical from a safety standpoint and should be inspected on any used M157 purchase.
How long will an M157 last?
With disciplined maintenance — including oil changes every 10,000 miles, timely spark plug replacement, and proactive turbo oil line servicing — the M157 is capable of exceeding 200,000 miles in moderate use. Hard-driven or poorly maintained examples tend to develop turbo and phaser issues well before 100,000 miles.
How does the M157 compare to the M156 it replaced?
The Mercedes-Benz M156 was a naturally aspirated 6.2-liter unit celebrated for its linear power delivery and mechanical simplicity. The M157 offers significantly more torque at lower rpm and greater efficiency, but introduces turbocharger-related maintenance complexity. Enthusiasts who prefer a raw, high-revving character often still prefer the M156, while those seeking usable daily power favor the M157.
What is the tuning ceiling of the M157?
On the stock turbochargers, the M157 can reliably reach approximately 680 – 720 hp with supporting bolt-on modifications. With upgraded or hybrid turbos and proper fueling, figures in the 850 – 950 hp range are achievable, though this requires significant investment in drivetrain and cooling support. The engine block and bottom end are robust enough to handle these power levels when properly built.
Can the M157 be used as a daily driver when tuned?
Yes — a Stage 1 or Stage 2 tuned M157 remains perfectly docile in daily driving. The ECU remaps from reputable tuners maintain all factory drivability maps and simply optimize the boost and fueling parameters. The engine's broad torque curve actually makes a tuned M157 easier to drive in traffic than many high-strung naturally aspirated alternatives.
Conclusion
The Mercedes-Benz M157 is one of the finest turbocharged V8 engines produced in the modern AMG era — combining hand-built craftsmanship, prodigious output, and real-world durability into a package that enthusiasts continue to seek out. Its known issues are manageable with proactive maintenance, and its tuning potential is exceptional for a factory engine at this displacement.
Overall Reliability Score: 7.5 / 10
Tuning Score: 9 / 10
Browse our parts catalog to find everything you need to maintain, repair, or upgrade your M157-powered AMG vehicle.