BMW M40B18 engine

Production of the M40B18 engine started in 1987. The engine is the older brother of the M40B16, which appeared a year later. The engine is the first in-line four-cylinder unit in the M40 family. 1.8-liter engines M40B18 were completed on cars BMW 3 series E30, E36, as well as BMW 5 series E34. The unit was used on cars with the factory index 18i. In addition, since 1989, there was a parallel production of a sports modification of the 1.8-liter engine M40B18. In 1992, the power unit was replaced by an updated version M43B18.

The engine is based on a cast iron cylinder block. The photo shows that the block is covered by an eight-valve head with a single camshaft. Also in the design of the BMW M40B18 engine there are hydrocompensators, thanks to which there is no need to adjust the valves after every 10 000 km. The diameter of the intake valve is 42 mm, and the exhaust valve is 36 mm. The piston stroke on this motor is 81 mm, and the cylinder diameter is 84 mm. The engine is able to develop maximum power up to 113 horses at 5500 rpm, along with this, the value of torque reaches 162 Nm at 4250 rpm.

BMW E36 M40B18 engine is equipped with a belt drive timing mechanism, characterized, according to owners’ reviews, by extreme unreliability. The resource of this element is only 40 000 km. A negligent attitude to the problem leads to belt breakage, which in turn inevitably leads to bent valves.

Fuel consumption is about 10.3 liters of gasoline in city mode, and 6.7 liters per 100 km on the highway. For BMW M40B18 engine oil of viscosity 5W30, 5W40, 10W40, 15W50 is best suited. The filling volume is 4.0 liters. It is recommended to change engine oil for BMW E30 M40B18 every 7,000 – 10,000 km or every 24 months.

M40B18 engine specifications

Advantages

The M40 family replaced the outdated M10 engines. From the predecessors, the novelty received the best design qualities and parameters, as well as acquired new positive features. The last power unit M40B18 came off the assembly line in 1994, but until now, cars with this unit enjoy success in the car market.

Among the main advantages of the engine are the following most important ones:

• Low fuel consumption;
• Low cost;
• No oil consumption;
• Repairability and adequate cost of work.

The M40B18 motor has a life expectancy of more than 250,000 kilometers.

Disadvantages

Despite the good description, decent characteristics of the M40B18, reliability, the motor still has a number of significant sore spots:

• Knocking in the engine. The malfunction occurs due to wear of the camshaft, hydrocompensators and rocker arms. The problem begins to bother the car owner after 200,000 km of mileage.
• Stalling during acceleration may be caused by dirty injectors that need to be cleaned or replaced.
• If the revs are floating on the BMW M40B18, it is recommended to check the integrity of the air duct. If there is no damage, try to find a problem in the mass air flow sensor, throttle valve. Often the cause may be heavy rotation of the camshaft.
• If the engine overheats, inspect the radiator, thermostat, cooling system, and plastic parts.
• Problems with starting the engine are associated with faulty gasoline pump, spark plugs, coil.
• Timing belt. Unreliability and low life of 40,000 km is a significant disadvantage of this engine model.

It should be noted that the production of the BMW E30 M40B18 engine has long been completed, which means that it is quite problematic to find a decent, problem-free copy on the secondary market.

Modifications

Among the m40b18 motors there is a single type with a working volume of 1.8 liters and a maximum output of 113 horses at 5500 rpm. The torque is 162 Nm at 4,250 rpm. Acceleration from start to 100 is carried out in 10.3 seconds with a maximum possible speed of 192 km/h.

Chip tuning

To increase the power characteristics, owners often resort to chip tuning. By the way, tuning on the M40 series of motors is not an economically profitable monetary investment. It is easier to buy a used M50 power unit and successfully improve its characteristics.

To improve the power of the M40B18 engine, a stroker is the best option. The procedure consists in increasing the engine displacement to 2.1 liters by replacing the crankshaft from M47D20 with a stroke of 88 mm, the pistons from S50B30, connecting rods from M44B19. The cylinder head, timing, intake and exhaust, electronic control unit are taken from the M44 engine. The measure will allow the engine to produce up to 160 horses.

Installing a turbo on an M40B18 is a better idea due to cost, 150 horses of power, and significantly reduced life expectancy.

This engine is installed on the following models:

BMW 3-Series (E36)

BMW 3-Series (E30)

BMW 5-Series (E34)