Mercedes M271 CGI Engine Problems And Reliability

In 2002, Mercedes-Benz vehicles were fitted with a new 4-cylinder petrol engine built from scratch. This engine is known as the M271 CGI.

The working volume of the new power unit is 1.6 or 1.8 liters. The engine grew from 122 to 202 hp. It is installed on the Mercedes-Benz W203, W204, CL203 (C-class), W211, W212, C207 (E-class), R171, R172 (SLK) cars and even on the Sprinter W906.

The aluminum beam contains a cast iron sleeve. The equalizer shaft maintains excellent smoothness.

The aluminum cylinder head on the M271 engine contains two camshafts, each of which is equipped with a phase shifter. Hydraulic lift is provided at valve actuation.

In general, the M271 engine has two types of block heads: for direct injection (DE) and intake manifold injection (KE).

The piston configuration of these engines is also different: a fuel gap is provided at the bottom of the pistons of the direct injection engine.

The connecting rod for the M271 engine was borrowed from its predecessor, the M111 Evo. Until 2009, the M271 engine was equipped with the Eaton M65 drive compressor.

In 2009, the engine underwent its first major upgrade. The engineers left the compressor. Now the turbocharger is responsible for the IHI AI0065 / 66 turbocharger.

In 2011, this engine received a successor – M270 / 274, which gradually began to replace it in Mercedes-Benz cars.

M271 Engine Problems And Reliability

The simplicity of the power unit created in the 2000s leaves much to be desired. This also applies to the general gasoline engines of Daimler engineers.

The portfolio contains several troublesome issues that are expensive to fix.

  • Timing Chain Problems
  • Crankcase Ventilation Problems
  • Oil Gasket and Heat Exchanger Leak Problems
  • Carbon Deposits on The Inlet Valve
  • When the engine is cold, exhaust often comes out of smoke

1. Timing Chain Problems

Chains are used in the M271 engine timing drive. Initially these motorbikes were equipped with roller chains, later manufacturers started using flat tooth chains instead.

However, the circuitry on this M271 engine was malfunctioning. This is especially true for silent toothed chains.

Over time, the chains on this engine stretch. If the car owner loses this moment, the chain will skip one or more gears.

When the chain is critically stretched, the “teeth” wear unevenly on the phase-shifting clutch stars, which only increases the risk of overshoot and the cost of engine repair.

In the worst case, the chain can simply break, causing the pistons and valves to collide.

How old is the M271 engine chain? The duration of its service, as training shows, is very small – no more than 100,000 km.

Engine with extended chains have problems starting, running unevenly, misfiring and knocking, and emitting metal grinding or clinking characteristics.

The worn chain with tensioner, phase shifting clutch can be replaced without removing the M271 engine from the engine compartment.

2. Crankcase Ventilation Problems

The crankcase ventilation system is designed to remove exhaust gases into the crankcase and the space under the valve cover. Burst gas occurs during operation on any engine. The gases are discharged, or rather exhausted, into the intake manifold, and thus sent back to the combustion chamber.

If there are problems with the crankcase ventilation system, the following problems will arise:

  • Excessive gas pressure compresses the oil seals, causing them to squeeze and / or leak oil through them
  • The blown gas can exert back pressure, which prevents oil from flowing through the drain in the piston, resulting in high oil consumption for waste
  • Engine oil begins to penetrate into the intake manifold
  • There is also misfire, which is manifested in the uneven operation of the engine
  • In advanced cases, oil from the crankcase in the form of thick vapor is sucked into the intake and settles in the intercooler. As a result, you can simply “drive” into the crankcase drain with the engine jammed.

All these “problems” appeared on the Mercedes M271 engine. The cause is the clogging of the oil clogs in the delivery gas cylinder from the crankcase to the oil separator.

The check valve located in this tube is also blocked or damaged.

If you suspect the condition of the crankcase ventilation tube, it should be replaced with a valve.

3. Oil Gasket and Heat Exchanger Leak Problems

The Mercedes M271 engine receives a unique oil filter housing made entirely of plastic. An aluminum heat exchanger is also built into it – inside, at the bottom.

With active and dynamic drive, engine oil heats it strongly, which in turn causes deformation and oil leakage. If the owner is not very active driving, then over time, due to old age, many heat exchanger gaskets and glass bodies are damaged and crushed.

There is a gasket here between the engine block and the body itself with the heat exchanger, as well as inside – between the plastic body and the aluminum heat exchanger.

An oil leak causes the following problems:

  • The oil seeps out, dripping into the pan. When the car is moving, the airflow discharges oil to the oil level sensor and to the connector located near the automatic transmission. These are the outward and early signs of a leak in the oil filter housing seal.
  • Due to defective gaskets, the antifreeze and oil can mix, eventually causing damage to the cooling system or engine.

To eliminate leaks, it is necessary to replace the external gasket (between the engine block and the housing) and the internal gasket.

Also, it will not be superfluous to replace an unreliable defect due to the heating filter housing of the number A2711801210 with the upgraded and more thermally stable A2711801410.

4. Carbon Deposits on The Inlet Valve

On the M271 engine with intake manifold injection, disturbances such as the formation of carbon deposits on the exhaust valve stem appear. The reasons for the formation of carbon deposits on the exhaust valve of the M271 engine are usually:

  • Take frequent short trips
  • Prolonged heating of the engine to operating temperature
  • Driving mode is too smooth without “turning” the engine to high speed
  • Refueling with low quality gasoline, which causes the formation of incorrect mixtures

Carbon deposits, solid and gummy, build up in a way that prevents the exhaust valve from closing. This issue does not cause a valve collision, but causes the following errors:

  • Misfiring, check the engine light
  • Uneven stationary
  • Decrease in engine power

In order to solve these problems, Daimler engineers have proposed several key solutions:

  • Replacement of the exhaust valve spring with a stiffer one
  • Installation of modified nozzles with 6 point nozzles
  • “Firmware” of the modified engine control (injection) program
  • Regularly adding Keropur cleaning additive to fuel (000 989 25 45 10)
  • Use of a valve with a rim for cleaning up carbon deposits – the modified valve received a newer version of the M271 engine

5. When the engine is cold, exhaust often comes out of smoke

The turbocharged M271.8 EVO engine later initially used the “wrong” bolt to secure the oil feed pipe to the turbo cartridge. The diameter of the hole in the screw is too large.

Therefore, when the engine is turned off, oil pressure presses it into the cartridge. Excess oil enters the hot parts of the turbine.

This situation in no way affects the power source of the turbine, however, burning oil in the intake manifold causes short smoke from the exhaust pipe after the cold engine is started.

To solve this problem, Daimler technicians replaced unsuccessful slotted screws with bolts with a nozzle (A 001 997 24 01), which precisely doses the supplied fuel and cuts off supply when the engine is stopped.


The M271 engine (and its bigger brothers M272 and M273, which we have already talked about) presents a lot of trouble for the owner.

This powertrain requires a lot of attention and quality care. If the built-in problems begin to manifest themselves as breakdowns, then the car will be arriving into service literally every month. Repairing the M271 engine will be very expensive.

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5 thoughts on “Mercedes M271 CGI Engine Problems And Reliability”

  1. Thanks for the article. M271 1.8l turbo sounds like a terrible engine based on the problems you described above. If maintenance costs are not so much a limiting factor, say you can find a garage that fix those wear and tear issues at a reasonable price, what are the goods of this M271 1.8l turbo engine? What do you think if I upgrade the turbo to a more power output, like north of 250hp+? Thank you


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