Find Used Mercedes Benz Engines For Sale

Since its introduction, the M272 has been used on almost all Mercedes-Benz models. V-shaped “six” M272 exists in versions with a working volume of 2.5, 3.0 and 3.5 liters . The V8 M273 engine was produced and exists with a displacement of 4.7 liters and 5.5 liters .

INTERESTING DESIGN FEATURES OF THE M272 AND M273 ENGINES 

The 272nd series of engines was developed on the basis of the power unit M112 E32 and, in fact, became its evolutionary development. The aluminum cylinder block of the new engines received the same camber of 90 degrees, and the inter-cylinder distance of 106 mm remained the same. The sleeves of the M272 / M273 motors are silumin , with a piston diameter of 92.6 mm and a stroke of 86 mm. The pistons themselves are lightweight, forged rods.

The blocks of both engines are made of aluminum alloy. The design of power units M272 / M273 embodied the original technological solutions and innovations that led to the complexity of their design and increased efficiency. For example, these motors have acquired systems for continuously variable valve timing on exhaust and intake camshafts. 

M272 / M273 engines were the first gasoline V-shaped units with phase regulators on the intake and exhaust camshafts.

The cylinder heads of the M272 / M273 engines are aluminum, with four valves per cylinder, hydraulic lifters and two camshafts . The inlet valve stems are thinner (thickness reduced from 7 mm to 6 mm). The diameter of the inlet valves is 39.5 mm, exhaust 30 mm. The timing chain uses a  double circuit . 

The fuel injection and ignition system of the M272 / M273 engines is a new generation of ME 9.7 from Bosch. Its control unit is installed directly on the intake manifold. To reduce the harmful effects of vibrations transmitted to the control unit, it is mounted on a vibration-damping “suspension” made in the form of elastic rubber pads. Most M272 / M273 engines have distributed injection, but the V6 (M272) engine has a direct injection (CGI) modification.

The engine control unit M272 and M273 is mounted on a vibration-damping suspension.

The exhaust manifold of the M272 / M273 engines has become more complex and capricious , but has increased engine efficiency due to the introduction of swirl dampers. The dampers control the air flow, increasing the speed of its air flow, as a result of which optimization and improvement of the distribution of the fuel-air mixture in the cylinders is achieved. The intake manifold of Mercedes engines of the M272 and M273 family is two-stage with variable length.

The powertrain control system represents the evolution of the ME 2.8 system used on the M112 and M113 engines. It was adapted for the M272 / M273 motors and also included the functions of system diagnostics. Data exchange between the control units is via a digital data bus (CAN).

TYPICAL PROBLEMS FOR THE M272 AND M273 ENGINES

The problems of the gasoline V6 (M272) and V8 (M273) can be heard without resorting to instruments. Often, an extraneous sound appears in the form of a knock, a clang of a chain, a metal ringing or rustling on a running motor . The sound source may be:

• extended timing chain
• worn star balancer shaft.

Replacing the timing chain on engines V6 (M272) and V8 (M273) should be carried out every 100,000 – 200,000 thousand kilometers. When the chain is stretched, uneven engine operation is possible.

BALANCER SHAFT GEAR

Wear on the balancer shaft sprocket is the most widespread and common problem with this engine . With the problem of replacing the balancer shaft on the M272 motor (or the intermediate gear on the V8 M273 motor), these motors face a mileage of 80,000 – 120,000 km . The problem appeared and still exists due to an engineering miscalculation: the material was incorrectly selected  for the manufacture of the balancing shaft gear (M272 engine) or the timing chain intermediate gear (M273 engine). The result is increased wear on the sprocket. At the service station, where there is good equipment and hands, a motoroscope with a flexible light guide is used to diagnose the condition of the sprocket: through the oil filler neck, it is possible to examine the condition of the sprocket teeth. If they are grounded – the motor is for repair.

Depreciation of the balancing shaft sprocket on the M272 motor leads to the following malfunctions:

• Knocking and clanging when the engine is running.
• Violation of the camshaft position adjustment of the right row of cylinders. Due to improper timing, the catalysts overheat and its pieces of ceramics fall into the cylinders, lifting the surface of the piston and cylinder, the surface of which is made using Silitec technology (silitek).
• Recording fault codes 1200 and 1208 (according to star diagnosis). 
• Label mismatch on the right cylinder head, intake and exhaust camshafts. At first, this malfunction does not affect the operation of the engine. In the future, there may be a loss of dynamics, increased gas mileage, extraneous noise from the engine.
• Clogging of the oil pump with metal chips, which can lead to jamming of the oil pump and, as a result, oil starvation.
• Due to the development of the sprocket, the chain tension is weakened, with heavy wear, the chain can jump with all the ensuing consequences, up to the bending of the valves.

If it was reliably determined that the gear is worn in the Mercedes V6 (M272) motor, then, according to the manufacturer’s recommendation, the following repairs will have to be performed :

1. remove the engine. There is an opportunity to do just removing the front cover from the engine, but in this case the repair will take place in difficult and very cramped conditions;
2. replace the balancing shaft with the unfortunate star;
3. replace the oil pump;
4. replace impulse sensors and magnets of camshafts in order to exclude the possibility of metal chips sticking to them;
5. replace the oil filter and the oil (with the required tolerance) in the engine. 
6. run in quiet mode (at speeds up to 80 km / h) for several tens of minutes.
7. replace engine oil and filter again. 

Petrol V8 (M273) for such repairs do not need to be removed. There, this ill-fated sprocket is an intermediate gear of the timing chain, and there is no balancing shaft in principle.

According to the manufacturer, the problem with gear wear was solved on V6 engines starting from engine number 2729xx30 468993 and on V8 starting from engine number 2739xx30 088611. But practice already shows that this is not the case: wear does occur, but only after much longer runs .

INTAKE MANIFOLD FLAPS

Another common problem with the Mercedes V6 M272 engine is a failure of the lever drive of the intake manifold flaps. The fact is that the intake manifold of the M272 and M273 motor is much more complicated than their predecessors. The inlet channels are equipped with movable dampers that control the intensity of the air flow and its swirl. This allows you to achieve powerful and uniform returns at low and high speeds. That is, in the entire range of engine operation. But the flaps became a weak point in the entire intake manifold design.

And again, the cause of all ills is the short-lived material – plastic, from which the damper actuator is made and they themselves. The flaps themselves are fragile. The high temperature at which they are forced to exist leads to drying out and destruction, crankcase gases with oil residues lead to their coking. Eventually, the flaps and their actuator begin to collapse.

The malfunction manifests itself with a range of 70,000-100,000 km in the form of uneven engine operation (“triple”). As planned by Mercedes engineers, the intake manifold needs to be replaced as a whole. You have to resort to this if at least one of the dampers is destroyed. If their actuator is destroyed, you can use an alternative solution: a damper actuator made of aluminum is on sale.

THE DETONATION OF THE “HOT” MOTOR

For runs of more than 150,000 km, it is recommended to combine the replacement of the balancer shaft with the replacement of valve stem seals. The fact is that the valve stem seals (valve seals) simply dry and tan, they begin to pass oil into the combustion chambers. The normal operating temperature of the coolant of the M272 and M273 engines reaches 100 degrees (the valve valves M112 and M113 worked at a coolant temperature of 87 degrees).

The operating modes of the radiator fans are also different. So on old viscous coupling motors, the fan worked immediately when the thermostat was opened, due to which a sharp decrease in the coolant temperature was achieved. The motors M272 and M273 fans are equipped with electric motors with intelligent control. And this intelligence turns them on at 107 degrees coolant , even though the thermostat opens earlier. As a result, such “intelligent” cooling control leads to a high risk of detonation. Most often, strong engine heating occurs during stops, which were preceded by rapid acceleration. The motor just does not have time to cool down quickly. The resulting detonation is very detrimental to the aluminum block: an explosive detonation wave easily destroys a thin layer of surface hardening of cylinders.

DESTRUCTION OF THE SURFACE OF THE WALLS OF THE CYLINDERS

Here we come to another very common problem of engines Mercedes V6 (M272) and V8 (M273). The detonation already mentioned above leads to the destruction of the surface of the walls of the cylinders. Scuffing on the surface of cylinders in engines V6 (M272) and V8 (M273) also occurs due to clogged or destroyed catalysts (by the way, both problems arise due to refueling with poor-quality fuel or the use of improper engine oil).

The catalyst, clogging, disrupts the normal operation of the exhaust system. As a result, the normal purge of the entire exhaust is terminated, the combustion chamber overheats and the associated destruction of engine parts. If the catalyst begins to collapse, then the particles of its ceramic lattice penetrate into the cylinders, where they settle on the cylinder walls and are “pressed” by pistons – on the mirror of the cylinders scuffing occurs.

Scuffing leads to oil “zhora”, which can be diagnosed both by a quick decrease in its level, and by a bluish tint of exhaust smoke. Further, the gap between the pistons and the cylinder walls increases, which is already diagnosed by the engine knock : the pistons begin to knock on the cylinder walls when shifting to top dead center.