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IA Technical Bulletin

BMW M40 Engine Guide

Engine: M40

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The M40 is a BMW four-cylinder gasoline engine built in two sizes, 1.6 liter (1,596 cc) and 1.8 liter (1,796 cc). BMW's repair data refers to a toothed belt for its camshaft drive. Wikipedia describes it as a single-overhead-camshaft engine.

BMW's parts data lists it in the E30 316i and 318i, the E34 518i and the E36 316i and 318i. Wikipedia says it replaced the M10 and was phased out after the M43 arrived. This is a short guide because the M40 was not sold in US-market BMWs, per BMW's own vehicle lists (data to December 2019).

M40 At a Glance

Question	Practical answer
Sold in US-market BMWs	Not sold in US-market BMWs, per BMW's own vehicle lists (data to December 2019). BMW lists M40 types for Europe, Japan, South Africa and Indonesia.
Versions	M40 B16 (1,596 cc) and M40 B18 (1,796 cc)
Factory output	B16: 75 kW without catalytic converter, 73 kW with. B18: 85 kW without, 83 kW with. All at 5,500 rpm.
Cam drive	Toothed belt
Engine oil capacity	4.0 liters (about 4.2 US quarts) with a filter change
Engine oil specification	Not established yet. BMW's data sheet points to a separate operating-fluids document that we have not opened.
Reliability, cost, power potential	Not established yet. We are still researching this engine.

Where you find it

Rows are BMW's type list by market, with catalog dates, which are not production claims. The data used here ends in December 2019.

Market and models	Catalog dates (BMW)
Europe: E30 316i	05/1988-02/1994
Europe: E30 318i (two-door, four-door, convertible, Touring)	01/1987-02/1994
Europe: E34 518i (sedan and Touring)	04/1989-05/1994
Europe: E36 316i sedan	12/1990-02/1994
Europe: E36 318i sedan	12/1989-03/1994
Japan: E30 318i	06/1987-04/1991
South Africa: E30 316i and 318i, E36 316i	E30 01/1987-02/1992; E36 01/1991-03/1994
Indonesia: E36 318i	05/1991-08/1993

Technical Specifications

Specification	M40 B16	M40 B18
Displacement	1,596 cc	1,796 cc
Bore x stroke	84 mm x 72 mm	84 mm x 81 mm
Compression ratio	9.1:1	8.8:1
Power, no catalytic converter	75 kW at 5,500 rpm	85 kW at 5,500 rpm
Power, with catalytic converter	73 kW at 5,500 rpm	83 kW at 5,500 rpm
Torque, no catalytic converter	143 Nm at 4,250 rpm	165 Nm at 4,250 rpm
Torque, with catalytic converter	141 Nm at 4,250 rpm	162 Nm at 4,250 rpm
Maximum engine speed	6,200 rpm	6,200 rpm
Valve head diameter	42 mm intake, 36 mm exhaust	42 mm intake, 36 mm exhaust
Oil capacity with filter change	4.0 liters	4.0 liters
Oil pressure	4.3 bar regulated	4.3 bar regulated
Thermostat opens at	92 degrees C	92 degrees C

Other data	Detail
Cam drive	Toothed belt
Valvetrain	Single overhead camshaft
Engine management	BMW's fault code list for DME M1.7 covers the M40; other DME versions not established
Coolant, E34	6.1 liters (6.5 liters with integrated air conditioning)
Coolant, E36	6.1 liters (6.3 liters with integrated air conditioning)
Fan clutch (M40 B18)	Switches on at 92 degrees C (plus or minus 4) and off at 60 degrees C
Engine oil specification	Not established yet.
Firing order	Not established yet.

Common Questions

What BMW has the M40 engine?

BMW's parts data lists the M40 in the E30 316i and 318i, the E34 518i and the E36 316i and 318i.

How much oil does an M40 take?

BMW's data sheet gives 4.0 liters (about 4.2 US quarts) for an oil change with a filter.

Does the M40 have a timing belt or a timing chain?

BMW's repair data refers to a toothed belt for the M40 camshaft drive.

Was the M40 sold in the US?

No. The M40 was not sold in US-market BMWs, per BMW's own vehicle lists (data to December 2019). BMW lists it for Europe, Japan, South Africa and Indonesia.

How much power does the M40 make?

BMW's data sheets list 83 kW (with catalytic converter) or 85 kW (without) for the 1.8 liter M40 B18, and 73 kW or 75 kW for the 1.6 liter M40 B16, all at 5,500 rpm.