Mercedes-Benz M272 engine
|Configuration||Naturally aspirated 90° V6|
|Displacement||2.5 L (2,496 cc)|
3.0 L (2,996 cc)
3.5 L (3,498 cc)
|Cylinder bore||88 mm (3.46 in)|
92.6 mm (3.65 in)
|Piston stroke||68.4 mm (2.69 in)|
82 mm (3.23 in)
86 mm (3.39 in)
|Valvetrain||DOHC 4 valves x cyl. with continuous VVT|
|Fuel system||Direct injection|
|Cooling system||Water cooled|
|Power output||204–306 PS (150–225 kW; 201–302 bhp)|
|Torque output||245–365 N⋅m (181–269 lb⋅ft)|
All M272 engines have aluminum engine blocks with a 90° V-angle with silicon/aluminum lined cylinders. The aluminum DOHC cylinder heads have 4 valves per cylinder. Direct injection is used in a limited fashion on the 3.5 L V6, whereas others use conventional port fuel injection. All have forged steel connecting rods, one-piece cast crankshaft, iron-coated aluminum pistons and a magnesium intake manifold. Like the M112, a balance shaft is installed in the engine block between the cylinder banks to deal with vibrations in the 90 degree V6 design. This essentially eliminates first and second order moments. A dual-length Variable Length Intake Manifold is fitted to optimize engine flexibility.
Continuous VVT was adopted for the first time. Featured on both the intake and exhaust camshafts, each can be varied through a range of 40 degrees. The twin spark plug system was replaced by a regular single spark plug per cylinder. New electronic coolant flow control has replaced the mechanical thermostat for improved engine warm-up and optimum control of engine temperature. Also tumble flaps are used to improve output at low engine speeds.
The E25 is a 2.5 L (2,496 cc) version. Bore and stroke dimension is 88 mm × 68.4 mm (3.46 in × 2.69 in). Output is 204 PS (150 kW; 201 bhp) at 6100 rpm with 245 N⋅m (181 lb⋅ft) of torque at 2900-5500 rpm.
The E30 is a 3.0 L (2,996 cc) version. Bore and stroke is 88 mm × 82 mm (3.46 in × 3.23 in). Output is 231 PS (170 kW; 228 bhp) at 6000 rpm with 300 N⋅m (221 lb⋅ft) of torque at 2500-5000 rpm.
The E35 is a 3.5 L (3,498 cc) version. Bore and stroke dimension is 92.6 mm × 86 mm (3.65 in × 3.39 in). Output is 272 PS (200 kW; 268 bhp) at 6000 rpm with 350 N⋅m (258 lb⋅ft) of torque at 3500 rpm. A direct injected variant debuted in 2006 under the name Stratified-Charged Gasoline Injection (CGI). First fitted to the CLS350 CGI, it produces 292 PS (215 kW; 288 bhp) and 365 N⋅m (269 lb⋅ft) of torque while lowering fuel consumption. In 2008, the non-CGI engine was uprated to 306 PS (225 kW; 302 bhp) at 6500 rpm and 360 N⋅m (266 lb⋅ft) of torque at 4900 rpm. This was achieved by raising the rev-limit to 7200 rpm, increasing the compression ratio and other modifications to the valvetrain.
Balance Shaft Gear and Other IssuesEdit
M272 engines that were sold between 2004 and 2008 with engine serial numbers below 2729..30 468993 often show early wear of the balance shaft gears, requiring extensive repairs at a retail cost of over $4000. These complaints led to a class action lawsuit against Mercedes-Benz (Greg Suddreth and Paul Dunton v. Mercedes-Benz USA, LLC), which alleged the M272 engines are equipped with defective balance shafts gears which "wear out prematurely, excessively and without warning, purportedly causing the vehicles to malfunction, the check engine light to illuminate and the vehicle to misfire and/or stop driving."  The suit further alleged that Mercedes knew of this problem, sending out repair bulletins on how to address this issue and ultimately changing the balance shaft gears to avoid this problem. This suit was ultimately dismissed with the judge agreeing with Mercedes that because the gears fail at 60 -80K miles and outside of the warranty period, Mercedes is not legally responsible for these problems.
However, a second class action lawsuit was filed in October 2012 in Northern California, covering Mercedes-Benz models manufactured between 2005 and 2007. A preliminary settlement was reached on April 8, 2015, which would see owners compensated for up to 70% of the cost of the repair. The settlement terms are expected to be ratified in August 2015.
These engines also have a common issue with their intake manifolds. The M273 also has similar issues but not to the same extent. The plastic lever that operates the opening and closing of the variable length intake manifold can break prematurely. Mercedes doesn't have this particular part listed, instead they sell the whole intake manifold as one unit which can cost upwards of $800 US. There are a number of third party companies that sell a replacement lever made out of metal at a much cheaper cost.
- O'Donnell, Matt. "Mercedes M272 & M273 Engine Class Action". Retrieved Aug 29, 2013.
- "Mercedes-Benz named in class action over safety issues related to its M272 or M273 engines". Retrieved Aug 29, 2013.
- Konigstiger. "How to interpret Balance Shaft Sprocket Engine Serial #?". Retrieved Mar 12, 2013.
- ZbylutMotorWorks. "Mercedes-Benz M272 Balance Shaft Failure". Retrieved Mar 12, 2013.
- O'Donnell, Matt. "Mercedes M272 & M273 Engine Class Action". Retrieved Mar 12, 2013.
- Jackson, Russell. "District Court Dismisses Automotive Class Action". Retrieved Mar 12, 2013.
- "Mercedes-Benz named in class action over safety issues related to its M272 or M273 engines". Retrieved Mar 12, 2013.
- "ORDER by Judge Thelton E. Henderson granting 142 Motion for Preliminary Approval of Class Action Settlement. Motion for Final Approval due 08/03/2015. (Filed on 4/8/2015)" (PDF). Retrieved June 29, 2015.