BMW M40

BMW M40
Overview
Manufacturer	BMW
Production	1987–1995
Combustion chamber
Configuration	SOHC Straight-4
Chronology
Predecessor	BMW M10
Successor	BMW M43

The BMW M40 is an inline-four SOHC piston engine which replaced the M10 and was produced from 1987–1995. It uses a camshaft belt like the 6 cylinder M20. Displacement ranges from 1.6 L to 1.8 L. The direct successor was the M43, which uses a chain driven camshaft, however in 1989 BMW also released the M42, a higher performance DOHC four-cylinder engine with the same block dimensions as the 1.8 litre M40.

The M40 engine uses Motronic 1.3 fuel injection system, has hydraulic tappets and are known for ticking over time, this is usually due to wear from oil starvation and poor maintenance, also M40 engine is more susceptible to lobe wear than any other E30 engine, usually caused by a blocked oil spray bar and a poor combination of materials. When the cam is worn, the engine will not "rev" high and the only solution is to replace it. Despite that, the M40 engine is in general a reliable engine, with some units approaching 300.000 miles without being overhauled.

Models

Engine	Displacement	Power	Torque	Redline	Year
M40B16 (E30 version)	1,596 cc	102 hp at 5,500	143 Nm at 4,250	6200	1987
M40B16 (E36 version)	1,596 cc	100 hp at 5,500	141 Nm at 4,250	6200	1991
M40B18 (E30 version)	1,796 cc	113 hp at 5,500	162 Nm at 4,250	6200	1987
M40B18 (E36 version)	1,796 cc	113 hp at 5,500	162 Nm at 4,250	6200	1991

M40B16

The M40B16 is a 1.6 L (1,596 cc) version of the M40 producing 102 hp (76 kW) and 105 lb·ft (142 N·m) of torque.^[1] The E30 version uses Bosch Motronic 1.3 fuel injection, while the E36 version uses Motronic 1.7.^[2]

Applications:

• 1988–1994 E30 316i
• 1990–1994 E36 316i
• 1992–1993 Bertone Freeclimber 2

M40B18

The M40B18 is a 1.8 L (1,796 cc) version of the M40 producing 113 hp (84 kW) and 120 lb·ft (160 N·m) of torque.^[2] Like the M40B16, the fuel injection system is Bosch Motronic 1.3 for the E30 versions and Motronic 1.7 for the E36.

Applications:

• 1987–1994 E30 318i
• 1988–1994 E34 518i
• 1992–1993 E36 318i

References

1. "BMW Heaven Specification Database | Engine specifications for M40 engines". Bmwheaven.com. Retrieved 2012-05-29.
2. Roy McNeill, Copyright BMW World 1999–2005. "BMW World – 4-Cylinder Engines". Usautoparts.net. Retrieved 2012-05-29.

See also

• List of BMW engines
• BMW M42
• BMW M43

External links

• The UnixNerd's BMW M40 engine page with photos, history and common problems.