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Mercedes Benz GLS Class GLS63 Engine Replacement Compare Prices & Get Quotes

Get quotes today from trusted UK Mercedes Benz GLS Class GLS63 AMG engine specialists. Compare prices on reconditioned, rebuilt and used engines for the hand-built 4.0-litre twin-turbo V8 - supply & fit available nationwide.

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Mercedes Benz GLS Class GLS63 Engine
from£7,500 to £13,50...
  • Usedfrom £4,500
  • Reconditionedfrom £7,000
  • Common codesM177.980
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How it works

3 Simple Steps to Finding the Right Replacement Engine

Clear information first, then the right engine and specialist for your exact vehicle.

Variant History

Mercedes Benz GLS Class GLS63 Engine History & Specs at a Glance

The GLS63 AMG launched with the X166 generation in 2012 as the GL63 AMG, powered by the M157 5.5-litre twin-turbo V8 - a thunderous 557-585hp powerhouse carried over from the ML63. In 2019, the all-new X167 GLS63 replaced it with the M177 4.0-litre twin-turbo V8 featuring hot-vee design and, from 2023, 48V EQ Boost mild-hybrid technology. In 2026, Mercedes-AMG unveiled the comprehensively revised M177 EVO with a new flat-plane crankshaft, delivering 603hp and 627lb-ft of torque.

Mercedes Benz GLS Class GLS63
  1. 2012

    M157, 5.5L twin-turbo V8, 557-585hp (GL63 AMG / GLS63 AMG, X166)

  2. 2019

    M177.980, 4.0L twin-turbo V8, 557-612hp (GLS63 AMG / AMG GLS63, X167)

  3. 2023

    M177.980 with 48V EQ Boost mild hybrid added

  4. 2026

    M177 EVO, 4.0L twin-turbo V8 with flat-plane crankshaft, 603hp

Every engine fitted to the Mercedes Benz GLS Class GLS63 is covered below, with UK rebuilt pricing and known failure points - from M157 cylinder scoring to M177 oil separator and rear main seal issues.

Engine Codes & Pricing

Mercedes Benz GLS Class GLS63 Engine Codes Specifications & Replacement Cost

Find your exact engine code, specs and UK replacement cost guide.

M157 — 5.5L Twin-Turbo V8 (2012-2018) engine

M157 — 5.5L Twin-Turbo V8 (2012-2018)

Power Output
557 hp (410 kW) (GL63 / early GLS63); 585 hp (430 kW) (GLS63 S)
Torque
700-760 Nm
Years Fitted
2012-2018
Displacement
5,461cc
Cylinders
V8, 32-valve, twin-turbocharged

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Common Problems

Mercedes Benz GLS Class GLS63 Engine Problems Repair Cost vs Replacement

The GLS63's M177 twin-turbo V8 is one of AMG's most impressive modern engines - a hand-built masterpiece assembled in Affalterbach according to the "One man, one engine" philosophy. However, as these vehicles accumulate mileage, several well-documented issues can drive significant repair costs. The most frequent and expensive problem is oil separator failure, which often leads to rear main seal leaks. Every rebuilt engine supplied through EnginesMarket includes upgraded components addressing the original failure point, plus a minimum 12-month unlimited-mileage warranty.

Common failure points and repair options

M177 Oil Separator Failure & Rear Main Seal Leak

Affected
Mercedes GLS63 AMG 4MATIC+, AMG GLS63 4MATIC+ (M177.980, 2019-present)
Typical failure mileage
40,000-80,000 miles
Root cause
The oil-vapour separator (cyclonic separator) is a known weak point on the M177 engine. When the separator becomes blocked, crankcase pressure increases significantly, and the weakest point in the crankcase seal system - the rear main crankshaft oil seal (RMS) - fails. This can start as a whistling noise or rough idle before escalating to a blown rear main seal. Mercedes-Benz mandates that both oil separators be replaced whenever a rear main seal is found leaking to prevent repeat failure.

Repair options

Repair tierDealer priceSpecialist price
Diagnosis - Oil separator/PCV check£250-£450£180-£320
Intermediate - Oil separator replacement£1,000-£1,600£600-£950
Major - Rear main seal replacement£3,500-£5,000£2,500-£3,800
Full Replacement - Rebuilt M177 engine£12,000-£18,000£7,500-£13,500
Our recommendation
The oil separator is the root cause of most M177 rear main seal leaks. If you notice oil around the transmission bellhousing, a burning oil smell, or hear a whistling noise from the engine, have the crankcase pressure checked immediately. If caught early, replacing the oil separators alone (£600-£950 at a specialist) prevents the much more expensive rear main seal replacement. If the rear main seal has already failed, replacing both the seal and the oil separators together is the only sensible approach. On a GLS63 worth £45,000-£85,000, the full rebuilt engine route is justifiable if bottom-end damage has occurred.
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M177 Turbocharger Failure

Affected
Mercedes GLS63 AMG 4MATIC+, AMG GLS63 4MATIC+ (M177.980, 2019-present)
Typical failure mileage
50,000-90,000 miles
Root cause
The M177's twin-turbochargers are mounted in the hot-vee configuration, subjecting them to extreme heat. Sustained high-temperature operation accelerates bearing wear, leading to oil burning and potential turbo failure. Coolant lines can also fracture due to age and heat cycles, causing cooling line failure and subsequent turbocharger failure if left unaddressed. Oil starvation is another contributing factor.

Repair options

Repair tierDealer priceSpecialist price
Diagnostics - Turbocharger inspection£250-£450£180-£320
Intermediate - Single turbocharger replacement£2,800-£4,500£2,000-£3,200
Major - Both turbochargers replacement£4,500-£7,500£3,500-£5,800
Full Replacement - Rebuilt M177 engine£12,000-£18,000£7,500-£13,500
Our recommendation
Preventative maintenance is the key to avoiding M177 turbocharger failure. Use only Mercedes-spec oil (MB 229.5) and change it every 10,000 miles or 12 months - never stretch the interval. If you hear a high-pitched whistle, notice a loss of power, or see blue smoke from the exhaust, have the turbochargers inspected immediately. Coolant lines should be replaced any time they are removed. If one turbo has failed, replace both - the other will typically fail within a short period due to shared oil supply and similar operating conditions.
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M177 Excessive Oil Consumption & Rough Idle

Affected
Mercedes GLS63 AMG 4MATIC+, AMG GLS63 4MATIC+ (M177.980, 2019-present)
Typical failure mileage
40,000-80,000 miles
Root cause
The M177 engine can suffer from excessive oil consumption, particularly if maintenance intervals have been stretched. Rough idle and vibration have also been reported, with some owners experiencing shaking at idle that persisted despite standard maintenance. Carbon buildup and oil consumption can creep in, especially if the engine wasn't maintained with regular oil changes and high-quality fluids.

Repair options

Repair tierDealer priceSpecialist price
Minor - Oil consumption diagnostics£200-£400£150-£300
Intermediate - Valve stem seal replacement£1,500-£2,500£1,000-£1,800
Major - Piston ring replacement£4,000-£6,500£2,800-£4,500
Full Replacement - Rebuilt M177 engine£12,000-£18,000£7,500-£13,500
Our recommendation
The M177 is a solid engine when maintained properly. If you notice increasing oil consumption, have a compression test and borescope inspection performed immediately. Carbon buildup and oil consumption can creep in, especially if it wasn't maintained with regular oil changes and high-quality fluids. On a GLS63 worth £45,000-£85,000, preventative maintenance is always the better investment.
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Don't Let Oil Separator Failure, Rear Main Seal Leaks, or Turbo Issues Write Off Your Mercedes GLS63 AMG

Whether you're facing M177 oil separator failure on your GLS63, rear main seal leaks, or turbocharger issues, EnginesMarket makes it simple to compare quotes from trusted UK Mercedes AMG specialists. Every rebuilt engine in our network carries upgraded components addressing the original design weakness - improved oil separators, reinforced rear main seals, and bench-tested turbos - plus a minimum 12-month unlimited mileage warranty with nationwide delivery and supply & fit options. Don't pay main dealer premiums. Compare prices from independent AMG specialists who know these hand-built V8 engines inside out.

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FAQ

Mercedes Benz GLS Class GLS63 Engine ReplacementFrequently Asked Questions

Everything Mercedes Benz GLS Class GLS63 owners usually ask before choosing a rebuilt, reconditioned or used replacement engine.

Why Choose Us

Compare Mercedes GLS Class GLS63 Engine Prices Today

Comparing quotes for your Mercedes GLS63 AMG is completely free, with no obligation and no pressure. Enter your registration above to get tailored quotes from UK Mercedes AMG specialists who understand the M157 and M177 V8 engines inside out. Whether you need a used engine, a reconditioned unit, or a full rebuilt engine with upgraded oil separators, rear main seal, and turbo components, we'll connect you with the right specialist for your exact GLS63 - with a minimum 12-month warranty on every engine supplied.

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