Common Mercedes M271 Engine Failures: Reasons and Consequences

The M271 is a four-cylinder gasoline engine developed by Mercedes-Benz, which was produced from 2002 to 2015 in Untertürkheim near Stuttgart. The engine made its debut in the Mercedes C-Class (W203) and was later used in the E-Class, as well as in other models with lower volume.

Compared to its predecessor, the M111, the M271 features variable camshaft adjustment on both the intake and exhaust sides. Additionally, the duplex timing chain was replaced by a simplex chain. Port injection remained, only in models with the CGI (Charged Gasoline Injection, e.g., C 200 CGI) addition was the mixture preparation switched to gasoline direct injection. Charging is carried out by a newly developed compressor, used in all variants of the series, thereby ending the era of four-cylinder naturally aspirated engines at Daimler.

In 2009, the M271 was technically overhauled and given the suffix "EVO" (M271 EVO). The most significant change concerned engine charging, which is no longer performed using a compressor but a turbocharger. The timing chain was changed to a toothed chain (previously roller chain), and Daimler finally parted ways with port injection.

Mercedes M271 Engine Problems

While the M271 unit can impress in terms of performance and consumption, the engine leaves something to be desired in terms of durability. Several weak points can lead to a complete economic loss. Below, we explore the most known problems of the M271.

Stretched Timing Chain

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The control times are no longer controlled by a duplex roller chain as with the predecessor. Instead, a simplex roller chain is used, known for causing severe engine damage through premature elongation. This is typically due to a defective chain tensioner, where wear is accelerated by late or missing oil changes.

The long production duration of the M271 suggests that this weak point was eliminated over the years. However, the timing chain remained an issue until the end, meaning that even with the M271 EVO, premature elongation may occur.

During vehicle inspection, it is essential to check if clattering or rattling noises can be heard during engine start (preferably cold) and load changes. If this is the case, the chain may already be stretched, and engine damage could be imminent.

Worn Camshaft Adjusters

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If the timing chain is gone, the sprockets of the camshaft adjusters often need to be replaced as well, as their teeth wear out prematurely due to material weakness. If this happens, the chain can easily jump and cause engine damage.

If wear is discovered during the chain replacement, a preventive replacement of the camshaft adjusters is recommended.

Oil in the Wiring Harness

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The solenoids of the camshaft adjusters become leaky over the years. This can lead to the wiring harness becoming saturated with oil, which can reach the engine control unit and cause damage there.

Although it does not necessarily lead to damage to the engine control unit, the risk increases with every additional drop of oil. This weak point can be remedied with an oil-stop cable (part number: A2711502733), available for a small amount of money and quickly installed. Since the M271 has two camshaft adjusters, two oil-stop cables are required. To stop the oil loss in the area of the camshaft adjusters, it is also recommended to replace the solenoids as well.

Carbon Formation in the Intake Tract and Valves

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Due to gasoline direct injection, the M271 EVO and older M271 units used in CGI models will have to deal with coked injectors and carbon deposits in the intake tract. To at least delay the resulting problems (loss of performance, higher consumption, etc.), it is advisable to use cleaning fuel additives at regular intervals when refueling.

Mercedes M271 Engine Specs

Series	Displacement	Power	Torque	Introduction
M 271 E 18 ML red.	1,796 cc (109.6 cu in)	105 kW (143 HP) / 5,200 RPM	220 Nm (162 lb-ft) / 2,500 – 4,200 RPM	2002
M 271 E 18 ML	1,796 cc (109.6 cu in)	120 kW (163 HP) / 5,500 RPM	240 Nm (177 lb-ft) / 3,000 – 4,000 RPM	2002
M 271 DE 18 ML	1,796 cc (109.6 cu in)	125 kW (170 HP) / 5,500 RPM	250 Nm (184 lb-ft) / 3,500 RPM	2003
M 271 E 18 ML	1,796 cc (109.6 cu in)	135 kW (184 HP) / 5,500 RPM	250 Nm (184 lb-ft) / 2,800 – 5,000 RPM	2007
M 271 E 18 ML /1	1,796 cc (109.6 cu in)	141 kW (192 HP) / 5,800 RPM	260 Nm (192 lb-ft) / 3,500 – 4,000 RPM	2002

Conclusion

The M271 represents a departure from the known quality that Mercedes-Benz is otherwise known for. Anyone considering a model with this engine should make sure that the service book has no gaps. Ideally, the timing chain, along with the chain tensioner and the slide rail, has already been replaced. Mercedes-Benz with the M271 engine may have a lot more hidden problems than it seems. You can read about them here.

If not, it is advisable to do this as soon as possible after purchase. The manufacturer also offers the option of determining, with the help of a measuring chain tensioner, whether there has been elongation and whether it is still within the standard range. Additionally, consideration should be given to taking out repair cost insurance to avoid being left alone with the workshop costs in an emergency.