BMW M40B16 engine

The M40 series small cars were launched in 1988. The engine was based on the M40B18, which became the first in-line four-cylinder engine in this family. Differences from its predecessor are in the reduction of working volume to 1.6 liters, which was achieved by reducing the stroke of the crankshaft, as well as the presence of different pistons in the structure. As for the connecting rods, these design elements have not been changed.

The M40B16 engine is an inline four-cylinder unit possessing eight-valve heads. The cylinder head is made of cast iron. The gasoline engine has one camshaft in the design, as well as hydrocompensators, thanks to which there is no need for self-adjustment of valve clearances after 10,000 km of mileage. Also a significant difference between the M40b16 unit and its 1.8-liter counterpart is the presence of a different intake manifold, throttle valve, electronic control unit (ECU), spark plugs. The diameter of the intake valve is 42 mm, the exhaust valve – 36 mm. The piston stroke is 72 mm and the cylinder diameter is 84 mm.

The M40B16 engine is equipped with a belt-driven timing chain. According to feedback from BMW M40B16 owners, the belt is not characterized by a high level of reliability, as well as the necessary width, and, as a consequence, does not have a long service life. It is necessary to change the timing belt and roller on M40B16 after about 40 000 km of mileage. The need for repair work will be indicated by a characteristic whistling sound from under the hood. Belt breakage leads to the piston hitting the valve head, which inevitably provokes bending of the valves by the motor.

Fuel consumption of BMW M40B16 is about 10.2 liters in city mode, on the highway this figure is much lower – 7.5 liters. Engine oil of viscosity 0W30, 0W40, 5W30, 5W40, 10W40, 15W50 is suitable for the engine. Oil should be changed every 7 000 – 10 000 km or once a year. Filling volume is 4.0 liters. Acceleration to 100 in the m40b16 engine takes 10.1 seconds.

The M40b16 powerplant is equipped with the BMW 3 Series with the factory index 16i. In 1993, the worthy M40b16 engine was replaced by an updated M43b16 unit.

M40B16 engine specifications

Advantages

Despite the last release of the motor from the assembly line in the distant 1994, cars with this engine continue to be successfully operated at present. Among the significant advantages of the m40b16 engine are the following:

• Low fuel consumption;
• Low cost, given its natural wear and tear;
• No increased oil consumption even on older versions;
• Accessibility and low price of repair work due to the simplicity of construction, lack of complex elements in the structure.

According to reviews of BMW M40B16 owners, the motor is characterized by reliability, and with timely maintenance and replacement of borers, the resource reaches 300,000 km.

Disadvantages

Despite its reliable performance and clever design, the M40b16 engine has a number of problems:

• Knocking in the engine. The cause of the malfunction lies in a worn camshaft, hydrocompensators or rocker arm. The problem catches up with the car owner after 200,000 km of mileage. It is important to periodically check these elements and, if necessary, perform timely replacement.
• RPM floating. As a rule, the cause is air intake due to a crack in the air duct on the DMRV. If there is no visible damage during inspection, it is recommended to check the mass air flow sensor (aka DMRV), throttle valve, lambda probe. In rare cases, the rpm may float due to heavy rotation of the camshaft.
• Failures during acceleration. BMW M40B16 owners note that the defect is caused by injectors that need to be cleaned or replaced.
• Motor overheating. The cause of the malfunction should be searched for according to a standard, established plan. To begin with, you should check the coolant level, inspect the radiator and plastic elements for cracks, assess the condition of the thermostat, pump, air plugs.
• If the BMW M40B16 does not want to start, you should pay attention to the work of the gas pump, spark plugs or ignition coil, wires, fuel system in general.
• Timing chain. Perhaps, this problem is the most common and annoying defect. This part of the engine is characterized by a low level of reliability, weakness, low resource. With the service life on other internal combustion engines, where the chain works more than 200,000 km, on the m40b16 the service life of the element is about 40,000 km. In this regard, it is important to monitor the condition of the timing chain and carry out its timely replacement.

In addition, do not forget that M40B16 engines are not produced at factories for a long time, so it is impossible to meet a new copy on the car market.

Modifications

There are two varieties of the M40B16 engine:

• M40B16, which was produced from 1988 to 1991. This modification is considered the basic one. There is no catalytic converter in the design, and the unit is capable of squeezing up to 102 horses at 5500 rpm. At the same time, the torque reaches 143 Nm at 4250 rpm.
• M40B16, the second modification already with a catalytic converter. The engine was produced for three years until 1994. The power of the power plant does not exceed 100 horsepower at 5500 rpm, and the torque is 141 Nm.

Chip tuning

To increase the power characteristics of the M40B16 engine, owners carry out chip tuning. According to experts, tuning of this series of motors is not the most profitable monetary investment. It is economically feasible to purchase a contract engine M50 and perform all the necessary metamorphosis with it.

If there is a great desire to improve the power characteristics of the m40b16 there is a stroker.

The essence is to increase the volume of the power plant. The working capacity of the unit is increased to 2.1 liters by boring the block to 86 mm, as well as the use of pistons from S50B30, connecting rods from M44B19. In addition, the cylinder head, timing mechanism, intake and exhaust manifolds are replaced, the electronic control unit is taken from M44. In general, the event will increase the power characteristics up to 152-162 horses.

Installing a turbo on a m40b16 is a futile endeavor that will yield a 150hp motor, but with less reliability and a significantly reduced lifespan.

This engine is installed on the following models:

BMW 3-Series (E36)

BMW 3-Series (E30)