BMW M40B18 Engine Specs And Problems

BMW M40 engine is a four-cylinder eight-valve engine with a volume of up to 1.8 liters and is installed on the BMW 3 Series (E30 and E36) and E34 5 Series.

After extensive preliminary testing, which mainly concerned the configuration of the cylinder head and combustion chamber – the final draft of the 4-cylinder BMW M40 engine was developed, powertrain manufacturing started in mid-1987 at the BMW plant in Steyr (Steyr) and continued until 25 April 1994. A total of 838 290 motor units were produced.

M40B18 was based on the 1.6-liter M10, but the rods were borrowed from the 2.7-liter M20.

For BMW E30 318i fuel injection system from Bosch Motronic 1.3 was installed, and for E36 318i – Motronic 1.7. In 1991 E34 518i, a new engine management system was installed – Digitale Motor Elektronik (Bosch-Motronic).

This engine has a belt-driven SOHC, an aluminum head, and a gray cast iron block that has become a substitute for the M10 engine. All fixing holes for the engine support are disposed of on the frame hard block portions.

It should be noted that the power unit of M10, in turn, was established over 25 years on various BMW models and contributed to the formation of a positive image of the company.

BMW M40B18 Specs

ManufacturerSteyr Plant
Also calledBMW M40
Cylinder block alloyCast iron
2 valves per cylinder
Piston stroke, mm (inch)81 (3.19)
Cylinder bore, mm (inch)84 (3.3)
Compression ratio9
Displacement1796 cc (109.6 cu in)
Power output83 kW (113 HP) at 5,500 rpm
Torque output162 Nm (119 lb·ft) at 4,250 rpm
Redline6,200 rpm
HP per liter62.7
Fuel typeGasoline
Fuel systemBosch Motronic 1.3 (E30)
Bosch Motronic 1.7 (E36)
Weight, kg (lbs)~132 (290)
Fuel consumption, L/100 km (mpg)
for E30 318i
10.3 (22.8)
6.7 (35.1)
8.6 (27.4)
TurbochargerNaturally aspirated
Oil consumption , L/1000 km
(qt. per miles)
up to 1.0
(1 qt. per 750 miles)
Recommended engine oil0W-30, 0W-40, 5W-30, 5W-40, 10W-40, 15W-50
Engine Oil Capacity, L (qt.)4.0 (4.2)
Oil change interval, km (miles)7,000-10,000
Normal engine operating temperature, °C (F)90-95 (195-203)
Engine lifespan, km (miles)
-Official information

300+ (185)
Tuning, HP
-Max HP
-No life span loss

BMW M40B18 Engine Oil Capacity

The BMW M40B18 engine requires 4.2 quarts of 0W-30 oil with a filter replacement.

What Cars Have A BMW M40B18 Engine?

  • BMW 318i E30
  • BMW 318i E36
  • BMW 518i E34

BMW M40B18 Engine Problems And Reliability

All problems you can face are similar to the BMW M40B16 engine.

The primary issue is a timing belt. It wears quickly and causes bent valves as a result of this. Keep an eye on the condition of your timing belt.

Some knocking and rumbling may be heard from the camshaft or damaged hydraulic lifters. It is critical to replace the camshaft if it is broken in order to prevent a costly repair down the road. A worn camshaft will not allow the engine to rev up very quickly.

Old engines, such as the M40B18, contain antiquated electronic components. Check the airflow sensor and oxygen sensor if your car’s idle is shaky or you have acceleration difficulties.

Dirty injectors are the most typical issue, which causes high fuel consumption and a loss of power.

Like other BMW engines, the M40 is vulnerable to overheating. Remember to clean your radiator and change the coolant in the system at the specified intervals outlined in your car’s maintenance schedule.

The M40B18 engine has an expected lifespan of 180,000 miles. The engine is strong on its own, but finding a vehicle with that motor and very little mileage is becoming increasingly difficult in today’s environment.


Was this helpful?

Thanks for your feedback!

The information provided in this article is for general informational purposes only. The author and publisher make no representations or warranties of any kind, express or implied, regarding the accuracy, adequacy, validity, reliability, availability, or completeness of any information presented. The reader is advised to consult a qualified professional, such as a mechanic or dealership, before making any decisions related to their vehicle's engine oil or maintenance.

About The Author