M178 engine — Mercedes-AMG 4.0 V8 (4L V8 32V DOHC Twin-Scroll BiTurbo Dry-Sump Direct Injection)
4L V8 32V DOHC Twin-Scroll BiTurbo Dry-Sump Direct Injection · 476-630 hp · 650-900 Nm
The M178 is the 4-litre twin-turbo V8 petrol engine from Mercedes-AMG, with 32 valves, direct injection, a dry sump and the turbos in the hot vee, built from 2014 to 2023 in outputs from 476 to 630 hp. It powers the AMG GT family (C190 and the X290 4-Door), the C63 S, E63 S, S63, GLC 63 S and GLE 63 S. Typical work covers camshaft adjuster solenoids clogged with varnish, a stretched dry-sump pump drive chain giving pressure warnings under hard cornering, carbon on the intake valves causing misfires, wastegate rattle, oil burning from hardened exhaust valve stem seals and short-lived plugs and coils. Any leak in the valley drops straight onto the turbos. There are torque figures for the head bolts, crank pulley bolt, main bearing caps, con rods, camshaft phaser centre bolt and dry-sump pump bolts.
Boost or power complaints start at the charge air cooler condensate drains, then wastegate travel, before a turbo is condemned. Phaser codes after an oil change may be stale adaptations, so reset them before replacing solenoids. For oil consumption, a cylinder contribution test separates a turbo seal on one bank from individual valve stem seals.
Check first
- Drain the dry-sump tank as well as the sump, around 2.5 L sits there; plug 25 Nm, new washer.
- Oil 5W-40 or 0W-40 MB 229.5, 10.5 L, every 10,000 km; not 229.51.
- Replace all four camshaft adjuster solenoids and screens together.
- Inspect the valley with a borescope and pressure-test the cooling system at every major service.
- Walnut-blast the intake valves; chemical cleaning does not shift baked carbon.
- Check chain stretch at 120,000 km using camshaft correlation values.
Engine overview
Manufacturer
Mercedes-AMG M178 platform
Displacement
4 L
Configuration
V8 32V DOHC Twin-Scroll BiTurbo Dry-Sump Direct Injection
Power
476-630 hp
Torque
650-900 Nm
Production years
2014-2023
Fuel type
Petrol
Vehicles with this engine
Mercedes-AMG GT (C190) 2015-2023
Mercedes-AMG GT S (C190) 2015-2023
Mercedes-AMG GT C (C190) 2017-2023
Mercedes-AMG GT R (C190) 2017-2023
Mercedes-AMG GT 4-Door 53 (X290) 2018-2023
Mercedes-AMG GT 4-Door 63 (X290) 2018-2023
Mercedes-AMG GT 4-Door 63 S (X290) 2018-2023
Mercedes-AMG C63 S (W205/W206) 2015-2021
Mercedes-AMG E63 S (W213) 2017-2023
Mercedes-AMG S63 (W222) 2017-2021
Mercedes-AMG GLC 63 S (X253) 2017-2022
Mercedes-AMG GLE 63 S (W166/V167) 2016-2023
Mercedes-AMG GTS (C190) Black Series 2020-2023
Known failures & weak points
Camshaft adjuster (phaser) solenoid failure at 60,000-90,000 km: the M178 uses four camshaft phasers (one per camshaft, intake and exhaust on both banks) fed by the dry-sump oil system. Solenoid screens clog with carbon and varnish deposits, causing P0010/P0011/P0013/P0014 codes, rough idle, and loss of low-end torque. Root cause is extended oil change intervals or non-approved oil viscosity. Replace all four solenoids and screens as a set, flush oil galleries, and use only MB-approved oil spec.
Dry-sump oil pump drive chain wear at 80,000-120,000 km: The external dry-sump scavenge/pressure pump is driven by a dedicated chain off the front of the crankshaft. Chain stretch causes oil pressure fluctuation warnings under hard cornering or track use, occasionally triggering limp mode. Symptoms: intermittent low oil pressure warning at high lateral g, oil pressure gauge oscillation. Full dry-sump pump chain kit replacement required; do not replace chain alone without pump inspection.
Cylinder head carbon buildup on intake valves at 50,000-80,000 km: Direct injection without port wash causes heavy carbon accumulation on intake valve stems and seats, particularly cylinders 1-4 (bank 1 runs hotter). Symptoms: rough cold start, misfires under load (P0300-P0308), reduced power above 4,500 rpm. Fix: walnut blast both banks with intake manifold removed; do NOT use chemical flush alone as it is ineffective on baked carbon. Recommend every 60,000 km as preventive.
Turbocharger wastegate actuator rattle and failure at 70,000-100,000 km: Both twin-scroll turbos (IHI units) suffer wastegate rod/bushing wear causing audible metallic rattle at idle and under light throttle, plus boost pressure inconsistency and P0234/P0299 codes. Root cause is thermal cycling fatigue on the actuator rod clevis pin. Inspect wastegate travel with XENTRY before condemning full turbo.
Valve stem seal oil consumption at 100,000-150,000 km: M178 exhaust valve stem seals harden and crack due to sustained high exhaust temperatures, causing blue smoke on cold start and overrun, oil consumption exceeding 0.5L/1,000 km. Confirmed more prevalent on track-used vehicles. Fix requires full cylinder head removal on both banks; Do not attempt with heads in-situ — access is insufficient.
Ignition coil and spark plug failure at 40,000-60,000 km: High compression (10.5:1 GT, 8.6:1 boosted effective) and sustained high-load operation degrade NGK ILZKR7B8EG iridium plugs and Eldor coil packs prematurely. Symptoms: misfires under boost (P030X), hesitation 3,000-5,000 rpm, slight fuel smell from exhaust. MB service interval is 60,000 km but track-driven cars require 30,000 km replacement. Replace all 8 plugs and coils as a set; mixing old/new coils causes uneven combustion.
Oil cooler and thermostat housing coolant leak at 80,000-120,000 km: The integrated oil cooler/thermostat housing assembly on the valley of the V8 uses multiple O-ring seals that harden and weep coolant into the valley, occasionally contaminating oil if undetected. Symptoms: sweet smell from engine bay, coolant loss without visible external drip, oil appearing slightly milky on dipstick in severe cases. MB part A2780000900 (housing assembly) and O-ring kit A2780160096. Labor is significant — intake manifold and valley cover removal required, 6h. Inspect at every major service.
Crankcase ventilation (PCV) membrane failure at 60,000-90,000 km: The M178 PCV membrane in the cam cover (separate units per bank) hardens and cracks, causing excessive crankcase pressure, oil consumption via intake, and oil leaks at cam cover gaskets. Symptoms: oil mist in intake tract, increased oil consumption, rough idle from lean mixture, P0171/P0174 codes. Fix: replace both PCV membranes (MB A2760101930 and A2760101830) and cam cover gaskets simultaneously. Commonly misdiagnosed as turbo seal failure.
Common torque specifications
| Head Bolts | Stage 1: 20 Nm all bolts in sequence (inside-out spiral); Stage 2: 90° angle; Stage 3: additional 90° angle — TTY bolts, single use only (MB A2760160220), never reuse; total 4 stages per MB WIS AR01.10-P-5800-01A unconfirmed |
|---|---|
| Crank Pulley Bolt | 150 Nm + 90° angle — TTY, single use; use flywheel locking tool MB 276 589 00 40 00 to prevent rotation unconfirmed |
| Main Bearing Cap Bolts | Stage 1: 25 Nm; Stage 2: 90° angle — TTY, replace after removal unconfirmed |
| Con Rod Bolts | Stage 1: 20 Nm; Stage 2: 90° angle — TTY, single use only (MB A2760380071) unconfirmed |
| Camshaft Phaser Center Bolt | 100 Nm — use camshaft holding tool MB 276 589 01 40 00; do not impact-gun; verify phaser locks in base position before torquing unconfirmed |
| Dry Sump Pump Mounting Bolts | 25 Nm — apply Loctite 243 medium-strength threadlocker; check torque at 10,000 km after any pump service unconfirmed |
Figures marked unconfirmed could not be cross-checked against a workshop source. Verify against the vehicle’s own documentation before tightening.
Service intervals
| Timing Chain | Duplex roller chain, no scheduled replacement interval — inspect at 120,000 km via XENTRY camshaft correlation values; replace if stretch exceeds 0.5° deviation on any phaser |
|---|---|
| Oil Change Km | 10000 |
| Oil Spec | 5W-40 MB 229.5 (track/AMG use) or 0W-40 MB 229.5 — do NOT use 229.51 LL spec in M178 due to LSPI risk under high boost; AMG factory fill is Mobil 1 ESP Formula 5W-40 |
| Oil Capacity L | 10.5 |
| Coolant Spec | MB Genuine Coolant Q1 03 0002 (blue, ethylene glycol, silicate-free OAT) mixed 50/50 distilled water — do NOT mix with green silicate coolant; system capacity 12.5L |
Pro tips from the field
Always perform a XENTRY 'camshaft adaptation reset' (long adaptation) after any oil change or camshaft/phaser work. The M178 stores phaser offset values in the ME9.7 ECU; stale adaptations cause phantom P0010-P0014 codes and rough idle that disappear after 200 km of driving — customers interpret this as a failed repair. Reset takes 3 minutes and eliminates callbacks.
The dry-sump tank (mounted left side of engine bay) has a separate drain plug and must be drained independently during oil changes — many shops only drain the sump pan and miss ~2.5L of old oil in the tank. Full oil change requires: sump drain, dry-sump tank drain, and filter replacement. Skipping the tank drain means you're leaving 25% old oil in the system. Tank drain plug torque: 25 Nm with new sealing washer.
When diagnosing boost/power complaints, always check the charge air cooler (CAC) condensate drain tubes before condemning turbos or wastegates. The M178 CAC sits in the valley and accumulates condensate water; blocked drains cause water ingestion misfires under hard acceleration that perfectly mimic turbo surge.
On high-mileage M178s with oil consumption complaints, perform a cylinder contribution test via XENTRY ME adaptation before recommending valve stem seals. Turbo seal failure (cheaper fix) and valve stem seal failure produce identical symptoms but different cylinder contribution patterns — turbo seal failure affects all cylinders on one bank equally, valve stem seals show individual cylinder deviation. This single diagnostic step saves quoting the wrong job.
The M178 uses a 'hot-vee' turbo layout (turbos mounted inside the V between the cylinder banks). This means any coolant or oil leak in the valley — PCV, oil cooler housing, thermostat — drips directly onto the turbine housings and exhaust manifolds. Even small leaks cause smoke and fire risk. Always pressure-test the cooling system and inspect the valley with a borescope at every major service; do not dismiss a single drop of coolant in the valley as minor.
Got a M178 problem? Ask for free.
Describe the symptoms — TorqFix replies with a diagnosis cited from verified workshop data.
Get free diagnosis →Who makes these pages, and how
TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
Variants of the same model differ. Cross-check torque against the factory manual for your engine before final tightening.
Seen a figure that does not match your manual? Write to us — we correct it and note when. support@torqfix.com
The story behind TorqFix →Workshop data on this page last updated 14 Oct 2026.