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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

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BMW M40B16 engine

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The engine was utilised in BMW 16i models until 1994, when it was superseded by the M43B16 engine, which debuted in 1993.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