BMW M40B16 Engine (Design, Issues & Tuning)
Updated: Feb 2
✔ This article has been fact checked.
BMW created the M40B16 engine, a SOHC straight-four petrol engine, between 1987 and 1994. It has a displacement of 1.6L producing between 98-102hp and 141-143nm depending on the version.
This engine has a bore of 84 mm and a stroke of 72 mm. It was used in the following cars.
1988-1994 E30 316i
1990-1994 E36 316i
1992-1993 Bertone Freeclimber 2
Table of Contents:
BMW M40B16 Engine Design
The manufacturer started making the 1.6-liter M40 series engine (official name M40B16) in 1988. This little engine was developed using the M40B18 engine, which has a 1.8-liter displacement and a longer stroke.
The cylinder block of this engine is made of durable cast iron. The 1.6l M40 engine employs the same connecting rods despite having a shorter stroke crankshaft than the M40B18 (the length is 140 mm).
To keep the compression ratio at the desired level, there are new pistons with a different form. It has a different intake manifold, throttle body, spark plugs, and ECU.
The cylinder head is made of aluminium. It has an eight-valve SOHC head with internal hydraulic tappets and lifters. Exhaust valves have a diameter of 36 mm, whereas intake valves are 42 mm in size.
The M40 camshaft has a duration of 244 degrees (single pattern), and the valve lift is 10.6 millimetres. A timing belt drives the camshaft.
It isn't as reliable as it might be. The belt has a short lifetime due to its low width. Every 25,000 miles, it is advised that the timing belt be changed. There is also a substantial risk of valves bending.
The engine was utilised in BMW 16i models until 1994, when it was superseded by the M43B16 engine, which debuted in 1993.
Engine Specs
Manufacturer: Steyr Plant
Production years: 1987-1994
Cylinder block material: Cast Iron
Cylinder head material: Aluminum
Fuel type: Gasoline
Fuel system: Fuel injection
Configuration: Inline
Number of cylinders: 4
Valves per cylinder: 2
Valvetrain layout: SOHC
Bore: 84.0 mm
Stroke: 72.0 mm
Displacement: 1596 cc
Type: Four-stroke, naturally aspirated
Compression Ratio: 9:1
Power: 102 hp at 5,500 rpm
Torque: 105 lb-ft (143 Nm) at 4,250 rpm
Firing order: 1-3-4-2
Engine oil weight: 0W-30, 0W-40, 5W-30, 5W-40, 10W-40, 15W-50
Engine oil capacity: 4.0L
Oil change interval: 9,000 miles (15,000 km) or 12 months
Applications: BMW 316i E30, BMW 316i E36
Problems & Reliability
BMWs M40 series' engines are all relatively good. The lifespan is between 180,000-200,000 miles.
The M40B16 does have several drawbacks, such a timing belt that can be unreliable. The age of this engine is its main weakness. Most of them require the rebuilding or replacement of a few aged components, and all BMW parts are pricey.
Common Issues
The M40B16 has some common issues, as listed below.
Timing belt problems: A thin timing belt causes expedited wear of the belt.
Cylinder head oil flow: All frictional engine parts in the cylinder head will wear down more quickly as a result of restricted cylinder head oil flow, necessitating more frequent engine maintenance. Regular oil changes and the use of stop-start oil may help.
Overheating: The deterioration of plastic flanges may lead to coolant loss and overheating as well as overheating.
Issues with efficiency and power: This common issue is caused by the l