🌍 International coverage, work in progress. This Russian-market vehicle is part of our hand-curated international catalog. We are filling in labor times, torque specs and fluids as fast as we can verify them, so some numbers may be missing or marked estimated for now. Do you work on these vehicles in the EU, Russia, or the JDM scene? Help us get it right: send real shop times or corrections to [email protected], or request the data you need and it joins the verification queue.
2018MERCEDES-BENZCLS
3.5L V6•RWD•AUTOMATIC•gas•M276
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The 2018 CLS (C257 generation) shares its M276 V6 and M278 V8 powertrains with older platforms and inherits their known weaknesses, particularly transmission cooler failures and catastrophic engine bearing issues on higher-mileage V8s. These are premium cars with premium repair bills when things go south.
M278 V8 Connecting Rod Bearing Failure
Occasional · high severity
Typical onset: 70,000-120,000 mi
Symptoms: Metallic knocking or rattling on cold start that may disappear when warm, Metal shavings in oil during changes, Check engine light with low oil pressure codes, Catastrophic failure: sudden loss of power, severe knocking, engine seizure
Fix: This is the nightmare scenario—rod bearings wear prematurely due to inadequate oiling or contamination. Once knocking starts, you're looking at a complete engine rebuild or replacement. 40-60 hours labor for short block replacement, plus machine work if rebuilding. Many owners opt for used/reman engines to save costs.
Estimated cost: $15,000-25,000
Transmission Oil Cooler Leak and Contamination
Common · high severity
Typical onset: 60,000-100,000 mi
Symptoms: Transmission fluid in coolant (pink/milky reservoir), Coolant in transmission (burnt smell, erratic shifting), Overheating transmission or engine, Limp mode or failure to shift properly
Fix: The 7-speed 722.9 and 9-speed 725.0 transmissions use an internal cooler that fails and cross-contaminates fluids. Requires cooler replacement, complete fluid flush of both systems, and often transmission rebuild if contamination went unnoticed. 8-12 hours for cooler/flush, add 20-30 hours if trans needs rebuild.
Estimated cost: $2,500-4,500 (cooler/flush only), $8,000-12,000 (with trans rebuild)
M276 V6 Head Gasket Failure
Occasional · high severity
Typical onset: 80,000-130,000 mi
Symptoms: White smoke from exhaust on startup, Coolant loss with no visible leaks, Overheating or fluctuating temperature gauge, Rough idle or misfires, Oil contamination in coolant or vice versa
Fix: The M276 V6 has weak head gasket design around cylinders. Both heads typically need gaskets, require machining to check for warpage, and often need new head bolts. 18-24 hours labor, more if heads need rebuilding.
Estimated cost: $4,500-7,000
Balance Shaft Module Failure (M276 V6)
Occasional · medium severity
Typical onset: 90,000-140,000 mi
Symptoms: Rough idle and vibration through chassis, Metallic rattling from engine at idle, Check engine light with cam/crank correlation codes, Oil pressure warning in severe cases
Fix: The balance shaft gear assembly at the rear of the V6 wears out or the chain jumps timing. Requires engine-out service to access rear cover. 20-28 hours labor for complete module replacement, new chains, and seals.
Estimated cost: $5,500-8,500
Transmission Mount Failure
Common · low severity
Typical onset: 50,000-90,000 mi
Symptoms: Clunk when shifting from Park to Drive/Reverse, Excessive vibration at idle in gear, Visible sag or cracking in rubber mount, Transmission noise transmitted into cabin
Fix: The hydraulic transmission mount deteriorates and loses damping. Straightforward replacement from underneath. 2-3 hours labor.
Estimated cost: $600-1,000
Airmatic Suspension Compressor and Strut Failure
Occasional · medium severity
Typical onset: 70,000-110,000 mi
Symptoms: Suspension warning message on dash, Vehicle sitting low, especially after sitting overnight, Compressor runs constantly or makes loud whining, Harsh ride or uneven stance
Fix: Airmatic struts leak and compressor wears from overwork. Individual struts are 3-4 hours each, compressor is 2-3 hours. Many owners convert to coil springs ($2,000-3,000) rather than keep repairing air system.
Estimated cost: $1,500-2,200 per strut, $1,800-2,800 for compressor
Owner tips
On V8 models, send oil samples to Blackstone Labs every 5,000 miles after 60k to catch bearing wear early—it's your only warning system
Check transmission and coolant fluids at every oil change for cross-contamination; catching cooler failure early saves $8,000+
Use only MB-approved 229.5 spec oil and change every 5,000 miles maximum regardless of what the computer says—these engines are oil-sensitive
Budget $2,000-3,000/year for repairs after 70,000 miles; if you can't swing that, don't buy this car
Beautiful car, but the V8's bearing issues and transmission cooler failures are financial grenades—only buy with impeccable service history and a healthy repair fund, or skip entirely for a newer platform.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.
Labor Times — 2018 Mercedes-Benz CLS
No labor entries for this vehicle.
Repair Procedures — 2018 Mercedes-Benz CLS
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Torque Specs — 2018 Mercedes-Benz CLS
No torque specs for this vehicle.
Fluid Capacities — 2018 Mercedes-Benz CLS
No fluid specs for this vehicle.
DTC Codes — 2018 Mercedes-Benz CLS
No DTC data for this vehicle.
Battery Specs — 2018 Mercedes-Benz CLS
No battery specs for this vehicle.
Control Modules — 2018 Mercedes-Benz CLS
Every control module on the 2018-2021 Mercedes-Benz CLS — where it lives, replacement time, and what it takes to program a replacement. Modules marked dealer / factory tool won't work after a part swap alone — budget for programming.
Transmission Control Unit (TCU)3.5 hr R&Rsecurity gateway +1.0 hr▸ programming details
📍 Transmission bell housing or valve body (internal on 9G-TRONIC)
🔧 Xentry Diagnostics + SCN online
⚠️ 9G-TRONIC transmission; TCU integrated into valve body, requires transmission oil service after replacement.
Climate Control Unit (CCU)2.5 hr R&Rdealer / factory tool +0.5 hr▸ programming details
📍 Behind center dashboard, above center console
🔧 Xentry Diagnostics
⚠️ Requires HVAC actuator calibration after replacement.
Electric Power Steering Control Unit (EPS)2.0 hr R&Rsecurity gateway +1.0 hr▸ programming details
📍 Steering column or rack housing
🔧 Xentry Diagnostics + SCN online
⚠️ Requires steering angle sensor calibration and end-stop learning after replacement.
4MATIC Control Unit (4M)2.0 hr R&Rdealer / factory tool +0.8 hr▸ programming details
📍 Under vehicle, near transfer case or rear differential
📍 Trunk, left or right side panel, or under rear shelf
🔧 Xentry Diagnostics
⚠️ Handles Mercedes me connect services; requires SIM activation and account linking.
Fuel Pump Control Module (FPCM)0.6 hr R&Rrelearn only +0.2 hr▸ programming details
📍 Trunk, right side panel or near fuel tank
🔧 Xentry Diagnostics or Autel
⚠️ Simple adaptation after replacement; no VIN-lock.
Aftermarket tool coverage varies by software version and vehicle build — treat "aftermarket tool" rows as "usually possible" and verify against your tool maker's coverage list before promising a customer. Spot a wrong location or hour? Tell us — corrections ship fast here.
Maintenance Schedule — 2018 Mercedes-Benz CLS
No maintenance entries for this vehicle.
Wiper Blade Sizes — 2018 Mercedes-Benz CLS
🌧️ Wiper Blades
2018
26″
Driver side
26″
Passenger side
Attachmenthook
📝 C218 generation final year. Sedan body style has no rear wiper.
Size-standard part numbers — verify your connector type before buying. Rear blades are model-specific; check the package's vehicle list.
Fuel economy figures are EPA data via fueleconomy.gov (median across matching trims). Performance figures are compiled estimates for the 2018 Mercedes-Benz CLS 3.5L V6 and can vary by trim.
🔧 Built by master technician Chris Hackleman · Master Technician · 20+ years.