"Is the S Serisi S350 reliable, and what should you check?"
When buying a used Mercedes-Benz S-Class S350 2014 (217 / 222), the most frequently mentioned issue: oil leaks from oil cooler seals or V-valley seals. Also, clogged Diesel Particulate Filter (DPF) is commonly reported.
Engine: OM642
OM642.861 · diesel · S350 · Used in this car from 2014-2015
Strengths
High service life with proper maintenance
Provides excellent vehicle dynamics
Watch-outs
Intake swirl flaps jam
Oil leaks quite common
Short-lived membrane of crankcase ventilation valve
Known engine issues
Oil cooler leaksThe most known problem of this diesel is oil cooler gasket leaks. Since the cooler is located in the V of the engine, replacing the cheap gaskets is expensive. Around 2010 the design was revised and such leaks no longer occur.
Fuel system issuesThe engine uses a reliable Bosch Common Rail fuel system, but its piezo injectors are very sensitive to fuel quality and expensive. Also, regular failures of the fuel quantity control valve in the high-pressure pump are noted.
Swirl flap problemsThe intake manifold has steel swirl flaps, but they are actuated by a servo with plastic rods that often break. The problem is worsened by intake clogging due to a weak crankcase ventilation membrane.
Listed from most frequently reported, each with its source.
Oil leaks from oil cooler seals or V-valley seals
Often reported
On the OM642 V6 engine, oil leaks from oil cooler seals or other seals in the V-valley are frequently reported. These leaks can require labor-intensive repairs involving removal of intake manifolds and upper components.
Engine Internal
Clogged Diesel Particulate Filter (DPF)
Often reported
On the 3.0 V6 CDI (OM642) engine, the DPF frequently clogs, especially with city or short-distance driving.
Exhaust Emissions
Clogged EGR valve and related warning lights/faults
Often reported
On the 3.0 CDI, carbon buildup in the EGR valve is a documented issue: the valve may stick or give signal faults, generating error codes and subsequently causing DPF clogging.
Exhaust Emissions
Turbo and intake manifold issues
Often reported
Deterioration or breakage in the intake manifold can cause turbo failures (oil leaks or impeller damage) and performance loss. Some vehicles report turbo issues after high mileage.
Turbo
Mercedes-Benz S Serisi S350 technical specs
Mercedes-Benz S Serisi S350 (2014): boot 510 L; fuel use 5,9 l/100 km (urban 7,3 l/100 km · extra-urban 5,1 l/100 km); 0–100 in 6.8 s.
Boot capacity
510 L
Fuel consumption
5,9 l/100 km (urban 7,3 l/100 km · extra-urban 5,1 l/100 km)
What should I look for when buying a Mercedes-Benz S-Class S350?+
When buying a 2014 S350, check service history, test drive, and engine/transmission warnings. Most commonly reported issues: oil leaks from oil cooler seals or V-valley seals; clogged Diesel Particulate Filter (DPF); clogged EGR valve and related warning lights/faults.
What are the chronic problems of the Mercedes-Benz S-Class S350?+
Most commonly reported issues: oil leaks from oil cooler seals or V-valley seals; clogged Diesel Particulate Filter (DPF); clogged EGR valve and related warning lights/faults.
Is the Mercedes-Benz S-Class S350 reliable?+
Instead of a simple yes/no, it is necessary to evaluate proven pros and cons together. This page lists 4 verified findings.
How does Carbeak collect data?+
The cards on this page are derived from Difetti fault database records; brand, fuel, engine, and generation compatibility between the source vehicle and target vehicle are verified. Topics with insufficient evidence are not shown.