Mercedes-Benz M272 engine
All M272 engines have aluminum engine blocks with a 90° vee 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 (2496 cc) version. Bore dimension is 88 mm and stroke is 68.4 mm. Output is 204 PS (201 hp/150 kW) at 6100 rpm with 181 ft·lbf (245 N·m) of torque at 2900-5500 rpm.
The E30 is a 3.0 L (2996 cc) version. Bore is 88 mm and stroke is up to 82 mm. Output is 231 PS (228 hp/170 kW) at 6000 rpm with 221 ft·lbf (300 N·m) of torque at 2500-5000 rpm.
- 2004–present SLK280
- 2005–present CLS280
- 2005–present CLK280
- 2005–2014 C280 (C300 in 2008)
- 2005–present E280 (E300 in 2007)
- 2005–present SL280
- 2005–present Viano
- 2006–present R280
- 2007–present S280
The E35 is a 3.5 L (3498 cc) version. Bore dimension is 92.6 mm and stroke is 86 mm. Output is 272 PS (268 hp/200 kW) at 6000 rpm with 258 ft·lbf (350 N·m) 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 (288 hp/215 kW) and 269 ft·lbf (365 N·m) of torque while lowering fuel consumption. In 2008, the non-CGI engine was uprated to 306 PS (302 hp/225 kW) at 6500 rpm and 265 ft·lbf (360 N·m) 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.
- 2004–present SLK350
- 2004–present CLS350
- 2005–present CLK350
- 2005–present C350
- 2005–2011 E350
- 2005–2010 S350
- 2005–present SL350
- 2006–present R350
- 2006–present ML350
- 2005–present Viano
- 2006–present Sprinter
- 2008–present CLC350
- 2008–2012 GLK350
Balance Shaft Gear Issues
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.
- 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.